February 1997 - JeffLuther.net
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1. Figure 2 The first tab displays showing a form association 10 Centura Pro February 1997 cfcDependents along with others This functional class could have functions to manipulate the database for the employee including such functions as creating a new employee or ahem terminating one This really shows the power of object orientation How do use it When the form is created read the data contained in the UDV into the appropriate objects data fields combo boxes etc on the form The value of data may be null so make sure that situation is handled correctly When the form is destroyed write the data back into the UDV The data in a functional class is persistent through this application session For example class variables in a functional class retain their information even when instances of the functional class are terminated It s convenient to have one function to read the data from the UDV into the form and one to write the data from the form to the UDV When you re in the windows variables section of a form the functional classes are shown as datatypes in the outline options The variables section of each of the three forms we have associated with our tabs will have the following defined cfcPersonal uPersInfo cfcAddress uAddress cfcDependents uDeps Using a late bound function The last capability needed to make this work is some way of knowing when a user has clicked off the tab so that yo2. String c_s Continued from page 8 Application Actions On SAM_AppStartup Set cFrm c_s Hello Class qualified reference Call SalCreateWindow frml1 hWndNULL A class qualified reference is similar to an object qualified cFrm frm reference except that a class name is used to qualify a reference Class qualified references are typically used in derived classes or class objects to reference an element in a base class Class qualified references are used to resolve multiple inheritance collisions An example and upon execution df1 in frm1 is initialized to Hello Fully class qualified reference A fully class qualified reference is similar to a fully object qualified reference except that a window handle Functional Class A expression is used to specify a particular instance of a F ti Oe ee tone Se class After being evaluated the window handle result must refer to an instance of the class or an object of a Functional Class B Functions class derived from the specified class Fully class qualified Function X en references provide a fair amount of flexibility and room F ti 1 i 2e e e ered rea for growth when designing class libraries or application Derived From Class A frameworks in applications themselves For example in Class B Functions Function x Call hWnd niIndex cFrm Initialize Actions Call A X eee the window handle result would have to refer to an instance of cF
3. Use Release 4 0 Scope Rules No the Tomahawk release of CTD which will support functions that return nothing VOID The converter will automatically change functions with no explicit return type to return a Number For every open a close Whenever you open a file or connect a Sql Handle ensure that you have a matching close or disconnect While an open File Handle isn t dangerous the runtime engine will close the file upon normal termination of the application detecting an open handle may point you to code that isn t being executed though you thought it was Connected Sql Handles at application termination can present problems with some back ends Suppose you build an application to work with SQLBase for development and forget to disconnect your Sql Handles at termination You then switch to Oracle for production A connected Sql Handle to Oracle at application termination can result in a GPF depending on which version of SQL Net you re using Application properties In SQLWindows these are items indented under the Design time Settings outline item see Figure 1 In Centura Team Developer right click on the Application node in the left pane and choose Properties from the menu Then select the Runtime tab in the properties dialog In either environment consider the following options e Use Release 4 0 Scoping Rules Always set this to No unless you have an application built with SQLWindows 4 0 and dependen
4. Because all of the tabs for a particular form are part of one source code module only one person can work on the form at a time Often projects are managed by checking in and out modules that control a form but this doesn t work with individual tabs on tab forms Forms on tabs can solve these problems What are forms on tabs So what exactly are forms on tabs If you ve used tabs you re familiar with the properties dialog The first five properties were there in prior versions of SQLWindows They allow specification of the attributes of the tab form such as the labels on the tabs fonts and colors of the labels and the internal tab name A sixth property was added in 5 0 2 that lets you associate a top level form form window or dialog box with an individual tab You ll notice in Figure 1 that there s a window name the tab label and the internal tab name which you can t see here Also illustrated in the figure is a nice feature which when you put the focus in the window name column shows a list of all of the forms from which to choose Another feature has been added to ease working with One great change introduced in SQLWindows 5 0 2 and temporarily left out of 5 0 3 was the capability of associating a form or dialog with one particular tab on a tab frame This article shows how this feature can conserve resources and improve team programming forms on tabs as shown in Figure 2 When a form is associated with
5. METH Pro Publishing PO Box 18288 Seattle WA 98118 0288 Source Code on CompuServe GO CENTURA Library 10 the acquisition of InfoSpinner First they gain an entirely new revenue stream ForeSite will be sold to companies that had not previously done business with Centura Since the death of runtime license fees it has been difficult for tool companies to get on going revenue from their customers Since ForeSite is based on deployment not development it represents a new form of revenue It s also a product that s a natural choice for OEM deals like the one with Software AG Of course ForeSite is also a near perfect fit for Centura s plan for large scale deployment of Web enabled applications created with Web Developer Without ForeSite Centura would have needed to allocate lots of resources to enhancing the JAWS server with the features found in ForeSite resources taken away from the ongoing tool development efforts And to industry analysts ForeSite is more likely to be well received than any deployment platform Centura might have created internally Centura management says ForeSite gives them an opportunity to visit accounts that hadn t previously chosen Centura tools It is essential for Centura Software to increase its customer base and ForeSite should open many doors Why did InfoSpinner choose to be acquired Lowery believes that there has been a fundamental change in management s vision at Centura recently H
6. Table Window tbl or tw Dialog Box dig Data Field df Multiline Field ml Column col Pushbutton pb Radio Button rb Check Box cb Option Button ob List Box lb Combo Box cmb Child Table tbl Horizontal Scroll Bar hsb Vertical Scroll Bar vsb Picture pic Custom Control cc Table 2 Additional popular naming conventions Item type Object type Resources Bitmap Icon Cursor Functions and Top Level Parameters Windows Classes Class Names Class Variables Instance Variables Named Menus Menus 4 Centura Pro February 1997 Name prefix bmp ico cur p corcls c i menu Some developers have devised schemes for naming functions but I haven t found one that suits me as far as prefixing a function so I just use unprefixed descriptive proper case names One area where I deviate from the common SAL naming conventions is in the naming of classes Personally I don t find it very useful to prefix class names with a c or cls As with functions I use an unprefixed descriptive proper case phrase as shown in Listing 1 Listing 1 Declaring classes and custom controls Global Declarations Example bDone dtStart hFileLog Islmage nProfit hSqlQuery sLastName hWndMain gbDebug hWndaChildren frmMain mdiFrame tblMain digLogin dfPassword mlComment colROWID pbClose rbFemale cbSavelnPreferences obTableView IbDatabases cmbTitle tb Details hsbPan vsbAspect picLogo ccM eter Example bmpSplash
7. I Continues on page4 entura Branching Out Mark Hunter hen Keith Lowery left Gupta Corp after six years of good service many developers regretted the loss of his talents I lost touch of his activities after that but debuted in January 1996 Software AG was sufficiently it appears that Lowery has been quite busy He is the founder and Chief Technical Officer of InfoSpinner Inc which has just agreed to be acquired by Centura Software Corp in exchange for 4 5 million shares of Centura stock In a conversation with Centura Pro he related some of the reasons he decided to rejoin his old employer InfoSpinner headquartered in Richardson Texas is in many ways a typical Internet oriented startup company At first staff meetings were held in coffee shops and source code was swapped on disk among engineers working out of their homes Now the company has 14 employees including eight engineers and an actual office Like other startups InfoSpinner was formed to address obvious needs in the young Internet intranet market especially the needs of large enterprises InfoSpinner created a product called ForeSite which impressed by the product to form a partnership with InfoSpinner and begin marketing the product under their name as iXpress Advance royalty payments from Software AG allowed InfoSpinner to keep growing the company and the product What does InfoSpinner offer InfoSpinner s main prod
8. a tab the tab displays a form icon and a little message that a form is so associated It is easy to see the design window associated with the form by double clicking on the icon Once you ve associated a form with a tab SQLWindows handles the creation of the form when the appropriate tab is clicked All of the standard SQLWindows messages such as SAM_Create occur for this form A fortunate combination of features OK you say That s fine if a user is only going to use a subset of the total number of tabs each time the tab form is used But if the form is created each time a tab is Tab Frame Properties Ea Tabs Fonts Colors Size Style Windows Window Hame Tab Label rsonal frmPersonal frm ddress frmDependents frmHR frmPersonal QuickTips A Form or Dialog Box window can be associated with atab When the tab is selected the window will be shown within the tab frame Figure 1 Associating a window name with a specific tab Centura Pro February 1997 9 chosen and all of the tabs are selected we can very quickly get up to using 400 or 500 child windows Here a powerful combination of features in SQLWindows or Centura Team Developer proves useful To take advantage of these features each form that is associated with a tab should contain a user defined variable UDV A UDV is a variable that is an instance of a functional class that the developer creates In the
9. example I ve provided they are instances of classes cfcPersonal cfcAddress and cfcDependents Each functional class has the data required for the particular form in other words cfcPersonal shown in Listing 1 contains variables for employee name ID and birth date as well as functions to access those variables Depending upon how the database is structured the functional class might contain functions to insert update and delete the data to the relevant tables in the database Many additional examples of UDV usage can be found in MUSQLB APP in the SAMPLES subdirectory of your SQLWindows or Centura directory Listing 1 The functional class for Personal form UDV Functional Class cfcPersonal Description Employee s personal information 0 Derived From Class Variables 0 String siEmpId 0 String siName 0 Date Time dtiBirthdate Instance Variables Functions Function Function Function Function Function Function GetEmpId PutEmpid GetName PutName GetBirthDate PutBirthDate effete I have found it useful to have a UDV for the entire tab form like a buffer for a database table or tables and contribute the UDV from each child form to this overall UDV Then that UDV might be type cfcEmployee and contain variables of type cfcPersonal cfcAddress and L Oo x E Human Resources Personal frmPersonal A window is associated with this tab Double click the icon to show the window
10. icoCustomer curDragCustomer p_RepeatCount cExplorerList c_hWndinstances i_sUserName menuFile Class Definitions Custom Control Class Slider Description Slider control Derived From Class Variables Instance Variables Functions Message Actions Form Window frmMain Description Main application window Named Menus Menu Tool Bar Contents Slider sldrVolume Message Actions Functions Window Variables Window Parameters Message Actions Listing 1 also shows another practice I like which is to prefix custom control class instances in a similar manner as the standard controls Thus all instances of the Slider custom control class are prefixed with sldr Another useful technique is to organize your variables I like to organize them alphabetically This makes it fairly easy to locate variables when browsing code I used to organize variables in the order they were referenced like in my structured programming days but this is harder to browse and often unknown in event driven environments I would also like to point out that naming conventions are guidelines rather than rules This makes it easier to allow useful exceptions Perhaps the best example of such an exception is in variable names for numerics that are really handles For these variables I generally choose to go with h as the prefix as in Listing 2 Listing 2 Allowing exceptions where appropriate Set hSysMenu GetSystemMenu hWndMDI I now
11. lines of code are invasive violating the spirit of encapsulation However object qualified references to functions are generally acceptable Set sLastName frmCustomer GetLastName Resolving references to duplicate symbols One of the reasons for object qualified references is to eliminate the ambiguity of duplicate symbols in different top level windows For example Form Window frml Functions Function fX Form Window frm2 Functions Function fX Dialog Box dlgl Window Variables String s Message Actions On SAM Create Set s X The compiler won t be able to resolve the assignment to s The solution is to qualify fX with the object name of the form whose fX function is to be invoked Set s frm2 f X Referring to child symbols in the context of a parent A suitable example Form Window frmMain Contents Child Table tblDetails Contents FlashableColumn coll Message Actions On SAM Destroy Call aTransaction Active FALSE Window Variables Transaction aTransaction Centura Pro February 1997 Message Actions On SAM_Timer Call tblDetails coll Flash The first occurrence of object qualification is the call to aTransaction Active The scope of the UDV aTransaction defined in frmMain extends to tb lDetails However the functions defined in the Transaction class aren t in the scope of tblDetails so an object qualified reference is necessary The second occurrence of object qualificat
12. on line help and Crystal s many Experts goa strengths is its 4 long way to ability to connect ia prevent a novice to virtually any Ehsan user from data source 2 Detail Block becoming Besides the lt lt intimidated typical data Page Footer Dkines Here are some of sources Crystal Report Footer Ulnes the more notable can connect to features Arbor s Essbase OLAP Figure 1 Centura s Report Builder interface A friendly Symantec s Act inter face Computer If you use Associates File Edit View Insert Format Database Report Window Help la x Centura s ee Slk MEA Zi alale vielz sioa viele glelal Too icrosoft s you ll feel a Exchange Excel J elz u Als 2 zal home with Design Preview NT event logs omaa a Crystal s user poe RecotHesde Sf R a e a Lotus Notes 3 x Page Header pl is similar Both and 4 x and a Deia Lol have report Report Footer i variety of Web RE AE templates server activity x divided into logs In addition For Help press Ft report bands or to the plethora of sections see ODBC devices the latest version of Crystal comes with a collection of native SQL routers for faster SQL access Native router support is provided for Centura s SQLBase Oracle and Sybase databases Centura s reporting tool s data source has to be either a Centura application or a CSV file Since Centura
13. s development products can connect to most of the above data sources indirectly Centura s reporting tool can too However this architecture which relies on DDE to transfer the data from the Centura application to the report engine adds another layer of overhead that hits 14 Centura Pro February 1997 Figure 2 Seagate s Crystal Reports Pro 5 0 interface Figures 1 and 2 These bands can be expanded contracted hidden or duplicated to customize a report template A tool bar and menus provide access to the various features In Crystal right clicking invokes context menus for quick and easy access to key functionality Once I became familiar with Crystal s interface it was no contest in terms of ease of use However not everything is intuitive and it does have its limitations One particular annoyance was the inability to undo after the use of certain Experts While Crystal does warn you that this is the case if you ignore the warning and don t save you learn the hard way that Experts aren t always right Another annoying limitation is the inability to drag and drop a group of selected items between report bands Fortunately Crystal allows you to move one item at a time a step above Centura s reporting tools which force you to cut and paste between bands It s also possible to open multiple report design windows at once and drag items from one report to another A Query tool allows you to take a graphical app
14. the contents of this publication including but not limited to implied 2 Centura Pro February 1997 warranties for the publication performance quality merchantability or fitness for any particular purpose Pro Publishing shall not be liable to the purchaser or any other person or entity with respect to any liability loss or damage caused or alleged to be caused directly or indirectly by this publication Articles published in Centura Pro reflect the views of their authors they may or may not reflect the view of Pro Publishing Opinions expressed by Centura Software employees are their own and do not necessarily reflect the views of the company Subscription information To order call Pro Publishing at 206 722 0406 Cost of domestic subscriptions 12 issues 119 Canada 12 issues 129 Other countries 12 issues 139 Ask about source code disk pricing Individual issues cost 15 All funds must be in U S currency Centura technical support Call Centura Software Corp at 415 321 4484 If you have questions ideas for bribing authors or would just love to chat about what you re doing with Centura products contact us via one of the means at right New Digs on the Web Centura Pro on the Web http www ProPublishing com Editorial Command Post Phone 818 249 1364 Fax 818 246 0487 E mail 71460 3142 compuserve com Subscription Headquarters Phone 206 722 0406 Fax 206 760 9026 E mail 71333 2142 compuserve com
15. CancelMode to deny the user s request way of 0 Returns programming Parameters The functional class is the primary location in the program not the form The data remains even after the form is destroyed The 0 Window Handle hWnd 0 Number nTab 0 Static variables Local variables o String sTag Number nWasIndex Actions gt Set nWasIndex hWnd cQuickTabs GetTop If nWasIndex nTab only do something if tabs change 0 Call hWnd cQuickTabs GetName nWasIndex sTag get the tag and number tab The DestroyPage function destroys the form associated with the tab but doesn t destroy the association so that when it is again selected the form appears 0 Call hWnd cQuickTabs DestroyPage sTag Centura Pro February 1997 11 different way of thinking about the situation That is the between forms and sharing data can be expanded and form has no direct knowledge of what is happening inthe possibly a topic for a later article tab or parent In many applications the user isn t allowed to save until certain information is supplied When The end of MDI all fields were on one form that was fairly straightforward An application or programming style is specific to an Now we ll achieve this same capability using variables that individual programmer But in this case I think it s easy to share the same class imagine that rather than using an MDI structure for Suppose an employee can t be saved to the
16. Formerly Gupta Pro Centura Code Warrior KL David burke Hot Ideas for Centura Developers February 1997 Volume 2 Number 2 f you develop applications for a living regardless of the tool you use you are faced with a significant number of issues in addition to the technical issues associated with programming There are pressures to get the product out the door provide a stable one hopes bug free product with a reduced time to market There are the issues involving the development support environment such as repositories version control and configuration management and the QA environment such as test plans and testing tools A large part of all this comes down to time spent debugging applications Therefore much research has gone on in finding ways to reduce time spent in debug mode This article doesn t present anything new or Every once in a while it s useful to be reminded of some of the most basic programming rules guidelines practices and disciplines that help us excel as software developers This article deals specifically with Centura Team Developer and SQLWindows but at a higher level many of the items discussed can be applied to most other software development environments You ll also find warnings and advice for those who need to prepare for Tomahawk intrude upon our creative nature Let s explore a few of particularly innovative it s more of a visit to thos
17. ag you may then call hWnd cQuickTabs DestroyPage sTag which destroys the form on the tab but won t eliminate the association between the tab and its child form When you go back to that tab the form will be automatically created Now you need to store the data that resides on the form into your UDV that was created for that purpose When the form is created there must be code to read data from the UDV and write it on to the form It works fine to write logic for those two tasks within the SAM_CreateComplete and the SAM_Destroy messages I reason the variables are class variables is so that even after the instance of the class is destroyed the form variable the class variables still exist Any other instance of the functional class shares in the functions and data in that class Therefore the function to write to the employee table the DB table that holds the employee s personal information might be in our cfcPersonal class and used from the main tab not the personal tab No knowledge of parent The most difficult issue is not really a difficulty but a Late bound Functions In CTD Using late bound functions is facilitated by Centura Team Developer When you are in an instance of a class and in the function section of the outline you can see all of the class functions available to you If you double click on the function you wish to implement a template name description variables of that function is create
18. al is impressive not only in its size and r 13 detail but also in its ability to anticipate common questions and issues For example I was interested in reproducing the greenbar paper effect that I often use with my Centura reports Sure enough the manual had a topic entitled How to alternate background colors for rows See my tip if you re interested in how it s done Other nice touches with the user manual are much appreciated For example it includes an extensive What s New section and a clever section Suggested Learning Paths for different types of users Moreover Crystal s wizard like Experts make the typical complex performance I have long suspected that this DDE interface has been Centura s Achilles heel when it comes to robustness Centura s reporting tool is adequate for short simple reports but I have often encountered problems when I have used it for larger batch reports Other users of Crystal s previous versions have reported stability problems so Crystal is not necessarily immune to this problem Features features everywhere The sheer number of features that Crystal 5 0 has is tasks easy almost You name it CENTURA Report Builder Untitled ME E overwhelming Crystal Reports File Edit View Report Tools Format Help The excellent connects to it Pos ___ width Times New Roman zijo z EEH B I uj documentation One of id oo Fm zi
19. alayer The dictionary metalayer provides a filter that simplifies and clarifies complex data forusers In other words the dictionary makes it easier for users to create their own reports There are many other advantages to using the Crystal Dictionary feature so if providing on the fly query and reporting capability is a requirement that s added incentive to investigate this useful feature While its Dictionary metalayer feature makes Crystal Drawing Library Launched TriLogic Automation BV in Amsterdam recently introduced its fourth utility for Centura develop ers TriLogic Shape Composer is a figure library that allows data to be presented as graphical objects in a diagram or drawing The advantage is that developers can use it to provide end users with real world metaphors representing their data and the logic of their programs Shape Composer includes a 16 bit SQLWindows version and a 32 bit Centura shipped on the same disk The company also publishes Class Explorer for SQLWindows a 16 Centura Pro February 1997 more user friendly for users there are better tools on the market that provide greater functionality and ease of use such as IQ Software Corp s IQ Objects Centura s answer to end user query tools is its aging Quest product which can t compete with these newer products on the market Web publishing tool Finally I wouldn t recommend Crystal as a Web publishing tool While it does allow for repo
20. all of Crystal s features However Crystal does have its limitations Although it s obviously a powerful client side reporting tool in trying to be all things to all people Crystal falls short when compared to its competition once it steps out of its bailiwick Client server reporting tool for large batch jobs The limitations of client side reporting tools become apparent when the client and server reside on physically different machines and large batch reports are a requirement In this case any client side reporting tool is going to fall short in terms of performance when compared to a server based reporting tool such as MITI s SOR Workbench Of course Centura s reporting tool is also client side and therefore suffers similar performance problems Note that Seagate has already recognized that Crystal can t be all things to all people and has introduced another product called Crystal Info This three tier client server reporting system allows users to schedule reports for immediate or future generation It uses Crystal Reports as the design tool and features a robust server based engine with good scalability Check out their Web page for more information on this new product www img seagatesoftware com cinfo default htm Ad hoc query and reporting tool Crystal isn t the best choice for an ad hoc query and reporting tool for end users It can be simplified for users by creating an optional Crystal Dictionary met
21. d in the outline for you LS recommen d Crea tin form i dow le File Edit Project Component Layout Debug Database Tools Window Help l WI gt lt lt 5 8 oleaj aele A aae E R a 0 ee class that always calls a function to restore data on the create and save the data to the UDV on the destroy By doing it all within the form the w Extemal Functions Internal Functions J Popup Menus capability works without regard to a Classes whether or not the form is associated ma with a tab Remember to use class a eral not instance variables in the E functional classes because you een destroy the instance of the class every E G Functions time you destroy the form By writing a function to save the data for each form you can easily handle special cases such as table windows ee Ore al gag s n H Function Tab ctivateFinish Function Tab ctivateStart Function TabCreate Function TabFrameResize Function TabSetFormPageSi 4 Add Next Level or extra data stored in form variables Outline view with coding assistant displaying class functions and specific template Q Description Indicates that user is attempting to change the current tab Drawbacks and caveats Data isin the Listing 2 An example of the TabUserRequest function UDV not the form Function TabUserRequest This is anew by clicking tabbing or some other user action Note Call
22. database many applications using a tab form with individual until a name birth date and address are supplied If the forms on tabs will be as flexible and perhaps more main tab contains variables of type cfcPersonal and intuitive for a user There are many functions available to cfcAddress the solution is again to use the functional manipulate tabs Examine the sample application class or classes that are instantiated by the UDVs used to QUIKTABS APP in the SAMPLES subdirectory for save the form s data If the main tab has UDVs that are of information regarding those functions CP the same class as the tab form s UDVs communication can happen through those same variables A simple call to Download FORMTABS ZIP from the Centura third party forum on CompuServe or visit the Centura Pro Web site at www ProPublishing com uVarPersonal GetName Larry Stahl is a consultant and founder of InterAct Consulting and a reveals the user s input or lack thereof Even combining Centura Software Training Partner He provides business requirements such queries into one function in the employee variable analysis project management design programming services and say cfcEmployee has a function IsAll Reqd would training to a variety of businesses He can be reached at make sense This entire concept of communications larry stahl juno com or on CompuServe at 71165 1012 Centura Code Warrior eo Class Variables
23. e says that they appear to have a solid plan for gaining market share and their technical directions are aligned with that plan Remember that InfoSpinner shareholders are accepting Centura stock not cash Lowery thinks that Centura stock at its current price is a good growth prospect Considering that the stock price rose 25 percent on the news in spite of the diluting effect of an additional 4 5 million shares the market shares those sentiments And InfoSpinner encountered challenges in remaining independent In the same way that Centura faced a lot of hard work to enhance Web Developer deployment InfoSpinner faced a lot of hard work to add more and better connectivity and other basic features to ForeSite Much of Centura s existing technology can be put to work quickly to make ForeSite even more attractive to potential customers Lowery noted the good fit between the two companies products InfoSpinner s future The InfoSpinner office in Richardson will become a branch office of Centura and the staff will remain to work on ForeSite and related products Lowery sees no sudden shift in direction for his engineers Centura is interested in InfoSpinner s products and wishes to keep enhancing and marketing them The products will remain open to all platforms and development tools And Software AG which kept InfoSpinner going in the early days is happy to see increased stability and functionality for the product their expectat
24. e early these days when we were taking courses in programming and system development Also you may not necessarily agree Naming with all the ideas presented here but at least it will start conventions Centura Code Warrior R J David Burke Branching Out Mark Hunter Centura News Real Time Goes Graphical Save Effort and Resources with Forms on Tabs Larry Stahl Reporting Tools The Answer is Crystal Clear Doug Mitchell Tip How to Create a Greenbar paper Effect Doug Mitchell Centura News Drawing Library Launched PRO Publishing you thinking about these issues and considering how you want to deal with them Coding practices We all develop our own programming style and preferences and this is indeed part of reason there are many rich and innovative applications out there So the last thing I would recommend are rigid programming rules that stifle our right brain thinking But there are many useful practices discovered over the years that don t Effective naming conventions give developers significant details about a variable or window in just a glance You can quickly discern the variable data type where it s defined how it s used and what it abstracts with a well developed set of conventions Most SAL developers start with the naming conventions recommended in the Developer s Reference manual reproduced in Table 1 In Table 2 I add some additional conventions that I ve taken to However
25. e graphics package that allows develop ers to create and customize cross platform 2 D and 3 D dynamic data displays for decision support The graphics can be built and deployed to the Web Windows or Unix Developers can use the utility to control monitor and represent data for execu tive information systems in industrial and finan cial applications The package which consists of 120 plus standard charts and graphics downloads drawings once the dynamic data then modifies the drawing based on a frequency determined by the programmer Pricing starts at 1 000 The product is expected to ship this quarter To learn more call 800 732 3200 or 413 586 4144 or visit www dvcorp com CP Centura Pro February 1997 3 Centura Code Warrior Continued from page 1 think there are still some conventions to work out Additionally you can use a naming convention for constants that don t fit well into the referenced tables This convention is to start with an upper case prefix typically two or three characters that identifies the constant group and then an underscore followed by a descriptive proper cased phrase SAM_ DoubleClick Table 1 SAL Identifier naming conventions Item type Object type Name prefix Variables Boolean b Date Time dt File Handle hFile Long String Is Number n Sql Handle hSql String sorstr Window Handle hWnd globals g type arrays a type Windows Form Window frm or fw MDI Window mdi
26. er choose a custom light gray shade as my alternate color Hint make the background color a light shade Otherwise when the report is copied or faxed the shaded detail lines can become illegible Using Crystal the process to produce the effect is not as simple nor intuitive Fortunately it s nicely documented within the user manual for version 5 0 on page 179 so won t detail the exact steps here The method takes advantage of the conditional formatting feature to conditionally suppress the background color formatting for alternating rows On the downside this method requires that you duplicate the entire detail band Asa result this means that enhancements and maintenance of the report becomes more of a hassle D M free runtime license is included It all depends conditional formatting One of Crystal s key features is its flexibility provided through its conditional formatting Using its If Then Else formula you can allow a report s content to change depending upon its source data While a programmer will be comfortable with Seagate s powerful Formula Editor used to control the conditional logic and more it is not as intuitive nor user friendly as the rest of the tool On the positive side users of Centura s reporting tool will be at home because Centura s Formula Editor has the same look and feel as Crystal s Centura Pro February 1997 15 What Crystal Reports is not It s easy to get overwhelmed by
27. find myself moving toward using Java naming conventions for several reasons First the Tomahawk 2 0 release of Centura Team Developer CTD will be quite Java centric generated Java code support for Java classes Second I think Java s style is more readable than the legacy SAL conventions Consider isDone instead of bDone and numltems instead of nNumlItems SAL supports up to 32 characters for identifiers This should give you the freedom to come up with meaningful descriptive names but it must be balanced against using names that are too long and difficult to read Remember you want to get maximum expressiveness out of variable names not maximum character length Comments The application outline includes many predefined items for entering comments and descriptive text However I ve seen source code for many production programs in which description items are mostly blank Given that typically a program is read many times but written once it only benefits us to document the code In the outline description items I like to use a format similar to the Windows SDK documentation for functions and a somewhat modified version for top level windows and classes In code comments are really useful as well especially for documenting non obvious algorithms and such However software development veterans know that comments can never be trusted typically when the code is changed by a junior maintenance programmer who doesn t bother u
28. her a Window Handle HWND or a Number DWORD Number HANDLE in CTD depending on whether you need to actually position a window or make it topmost Another reason for using ordinals is to avoid compile errors for duplicate function names For example if you write a general purpose APL that defines a Windows API function and you want to include it in an existing application you must determine whether the function is already defined in some other part of the app and perhaps modify code If your APL uses a different unique name for the function and defines the ordinal you can include the APL in the app without fear of duplicate symbol errors The second dilemma surrounding external functions is whether to map API functions that take a handle data type to a number or a window handle Both have their advantages and disadvantages Mapping an external handle data type to a window handle offers some protection from using the value in arithmetic operations which typically aren t a valid way to use the handle value However the value is now susceptible to being used as a window handle argument By using a number for the internal mapping you get better expression in CTD because you can choose Number HANDLE Also with the forthcoming changes in the Tomahawk release of CTD window references will replace window handles and this may make migration efforts more challenging More on functions While talking about functions here are some more t
29. ier that follows the window handle in the fully qualified expression If this is set to No and the check fails then you re guaranteed to get a GPF and a fatal abnormal termination of your app If it s set to Yes you ll get a friendlier error dialog that explains why your app is about to terminate Certainly helps with the debugging effort After thoroughly testing your app you typically set this to No for building the production EXE file to receive a modest performance improvement in code execution of these kinds of references See the on line help or manuals for more information on these items Object oriented programming OOP isn t something that can be covered in any significant detail in an article like this but there are important points to remember In the current implementations of SAL encapsulation is a discipline you have to maintain Refrain from external references to variables or child windows In the Tomahawk release we ll see support for encapsulation from the compiler A hot topic in OOP is whether to use multiple inheritance I believe multiple inheritance has its place and can be useful in many situations Others disagree and avoid using multiple inheritance Strive for reusability Use classes and inheritance and partition your library files to optimize the reuse of your work Get over the not invented here syndrome and look for other code that you can reuse Consider and evaluate the available class librarie
30. ion is the call to tblDetails col1 Flash The context for this call is within frmMain and since coll is a child element of tblDetails it needs to be qualified Also notice col1 qualifies the Flash function In an object qualified reference you can provide as many levels of nesting as necessary for your reference Arguably this second occurrence violates encapsulation Perhaps a better approach would be to send the tblDetails a message or call one of its functions which would execute the column qualified function call Fully object qualified reference In applications that support multiple instances of a top level window it is necessary to specify a particular instance in an object qualified reference This is supported by prefixing the object qualified reference with a window handle expression that provides the window handle of the instance you want to use Resolving references to multiple instances of a window Recall the following form window Form Window frml Functions Function fX Now consider the following Set hWnd1 SalCreateWindow frml hWndNULL Set hWnd2 SalCreateWindow frml hWndNULL Set s frm1l fX The object qualified reference frm1 fX is ambiguous in this case since there are two instances of frm1 The solution is to go to a fully object qualified reference that specifies the instance to use Set s hWnd2 frm1 fX Additional nesting is supported for fully object qualified references as
31. ions for ForeSite iXpress remain strong Why does the InfoSpinner Web page look so funny ForeSite is becoming a Centura product and Centura wants to create a coherent marketing plan for this important new part of the company While that s going on they have asked InfoSpinner to suspend its public marketing efforts Thus the empty look of www webspinner com OEM vendors may still publish product information for the current version of ForeSite but there really will be significant changes to ForeSite between now and the official Centura rollout later in the first quarter At that time a revised set of product specs and other information will become available You can also expect an in depth look at ForeSite s features in Centura Pro at about the same time Reading between the lines R J David Burke s Code Warrior article in this issue is full of good advice but the most interesting tidbits are those which discuss how Tomahawk and its conversion tools will deal with your existing SQLWindows and Centura applications It s not too early to start thinking about what you ll need to do to make your apps compatible with the future Centura Team Developer 2 0 At Pro Publishing we ve seen a little of the future and it s both daunting and exciting Preparing for Tomahawk will be a major focus of the newsletter in the months to come CP Real time Goes Graphical DataViews Corp recently announced DV Xpresso 2 0 a real tim
32. ips A useful practice to adopt is to always check and validate your parameters at the start of the function While some developers prefer to do validation on the arguments before calling the function from a modular and encapsulation perspective the function shouldn t count on this Another guideline for coding functions is to have only one exit point i e one Return Most developers who made it through structured programming retain this practice but the C community seems to have discouraged this style The benefit is readability If there s only one exit then it needs to be at the end of the function the exceptions are pathological and can be quickly located Centura Pro February 1997 5 Multiple Return statements make the code harder to read and typically introduce more code paths that need to covered during testing discussed in Part 2 of this article Finally get in the habit of explicitly coding a return data type for your functions While the current releases of SQLWindows and Centura Team Developer default to a numeric return data type this will change in Application Description SOLWindows version 5 0 starter application Design time Settings Outline Window State Normal Outline Window Location and Size Options Box Location Class Editor Location Tool Palette Location Fully Qualified External References No Reject Multiple Window Instances Yes Enable Runtime Checks Of External References Yes
33. ir the QuickReports feature has been added more recently but it enhances integration so it will be covered in the second article Let s face it there are only two reasons to use Centura s reporting Centura Pro February 1997 Crystal Reports Professional 5 0 Suggested retail 395 upgrade 199 Seagate Software Inc Information Management Group 1095 West Pender Street Vancouver BC Canada V6E 2M6 800 877 2340 604 681 3435 www img seagatesoftware com Professional edition Besides a few add ons the main features missing from the Standard edition are native SQL support ODBC access only to desktop data sources such as Access Excel and FoxPro and some programmability about half the number of API functions are exposed Therefore when using a client server development environment such as Centura s the Professional edition is the only way to go Weighing in at over 87 tons er megabytes Crystal comes in both 16 bit and 32 bit versions each of which installs easily from the CD When fully installed the 32 bit Professional edition consumes a whopping 87M The recommended RAM is 8M but 16M is more workable It runs on Windows 3 1 Windows 95 and Windows NT 3 51 or higher Luckily Seagate provides the necessary assistance for using its monster of an application The CD includes a computer based training course sampler a user manual of more than 700 pages and extensive on line help The manu
34. ition to the standard ability to print to a printer or a Preview window Crystal can export a report file through e mail as a fax directly to disk to a Microsoft Exchange folder to a Lotus Notes database or to an ODBC data source The report can be exported in any of several formats including word processing spreadsheet database file HTML or standard data exchange such as CSV DIF and RTF Crystal allows you to distribute a report to a user s desktop complete with a stand alone snapshot of data Using the Report Distribution Expert you can package a report with a current snapshot of data and any required components for stand alone viewing printing A royalty Centur How to Create a Ip Greenbar paper Effect One effect I created extensively with Centura s reporting tool was to alternate the background color or shade of detail lines in order to improve readability This effect mimics the green barred paper used by antiquated line printers Producing this effect is simple using Centura s reporting tool After selecting the Detail band choose the Line menu item under the Format menu Click on the Color button from the Format Line dialog box to access the Format Line Colors dialog box In the background group choose a color such as green and click on the Alternate Color check box Now the detail lines will alternate between the specified background color and no color Since often print on a black and white print
35. nested to any outline level This means for example that the scope of a data field in a form window is anywhere inside the form window including its functions other child windows message actions and menu The scope of global variables is anywhere else within the outline because you can think of the outline itself as the highest level of container To refer to an element of an application from outside its scope you need to use a qualified reference Generally I see qualified references as either external references referring to an element defined in a different top level window or MDI window or child references referring to an element defined in a child element this is my own term not in the documentation External references can be more specific by making them fully qualified which means a window handle expression is prepended to the qualified reference Another way to look at qualified references is that they are either object qualified or class qualified depending on what kind of reference you re trying to make What follows here is look at all the forms of qualification where and why you d use them and any other comments Object qualified references Object qualified references can take on a variety of forms in SAL Consider accessing a variable or data field ina form window outside of the current scope Set frmCustomer sLastName frmQuery sLastName Call SalHideWindow frmMain pbCancel Notice how both of these
36. pdating the comments and only trust the code itself This reality reinforces the adage If you can say it in code or say it in comments say it in code What this means is that if you can capture the essence of a code fragment with a comment vs with descriptive variable names and programming constructs go with the latter In self descriptive code the code itself will explain how it works In some cases it is helpful to augment the code with comments that explain why the code does it the way it does External function issues One dilemma with respect to external functions is whether to use export ordinals Generally I prefer not to unless required If export ordinals are used the compiler will compile external functions as long as any function has been exported with the specified ordinal regardless of whether it s actually the function you intended to call By not using export ordinals the compiler is forced to search binaries for functions by name which will cause the compiler to fail if the functions aren t defined and exported I m sure export ordinals are in the top three of migration problems when going from SQLWindows to Centura Team Developer A typical situation IMHO that justifies using export ordinals occurs when you need to declare the same external function more than once with different parameters A good example is the Windows API function SetWindowPos where you might redefine the second parameter to accept eit
37. rm or an instance of a class derived from cFrm Like fully object qualified references it is anticipated that Tomahawk will make the need for and use of fully class qualified references obsolete An interesting use of class qualified references is that they can be used to reference class variables even when there are no instances of a class For example you can do this Global Declarations Next month Test plans and testing CP Class Definitions Form Window Class cFrm i i A Contents RJ David Burke is a Project Leader with Centura Software Corp You can Data Field df1 aan a assajo ACETONE send him e mail via David Burke CenturaSoft com 12 Centura Pro February 1997 entura D Reporting Tools The Answer is Crystal Clear DYT ecause of Crystal Reports scope and complexity this article focuses only on the features and user interface of the product to provide you with a good understanding of Crystal s capabilities and limitations A second article which will appear in a subsequent issue of Centura Pro will focus on the integration of Crystal with various development environments particularly Centura s development products A review not a comparison To begin with this first article is more of a review of Crystal rather than a direct comparison of Crystal with Centura s reporting tool ReportWindows Report Builder Therefore you won t find any comparative feature checklist or perfo
38. rmance benchmark graphs However since you re probably familiar with Centura s reporting tool this article informally compares the two tools to each other frequently While both of these tools This article reviews Seagate Software s Crystal Reports 5 0 a popular and award winning reporting tool This program can be used as a powerful stand alone reporting utility or as a report engine integrated into your favorite development environment tool when products such as Crystal are available its price free and its tight integration with Centura s development products This second reason is very important to users of Centura s development tools therefore TI cover it thoroughly in the second article Go Professional Crystal comes in two versions the Professional edition which lists for 395 upgrades 199 and the stripped down Standard edition for 195 upgrades 79 The features discussed in this review are based on the are in the same category client side reporting tools Crystal is in an entirely different class Crystal is the Ferrari of reporting tools powerful fast friendly and slick looking By comparison Centura s reporting tool is more like a hand me down Yugo outdated slow sparse on features and not known for its reliability but free I am not out to bash Centura but just about the biggest change to ReportWindows in the last three years was its name change to Report Builder To be fa
39. roach to developing the underlying SQL queries for reports You may also enter SQL queries directly if you prefer Many Experts ready to assist you Crystal provides over a dozen Experts or wizards to guide you with such tasks as creating a variety of reports preparing graphs setting up your overall report format linking related databases selecting records for inclusion in your report and gathering the necessary files for report distribution Centura s reporting tool at least provides a Wizard for cross tab reports This is necessary because cross tab reports are one of the most complex routine reporting tasks Reporting types for all occasions One of Crystal s most useful features is its tab based wizard Create Report Expert This Expert leads you through step by step instructions for creating a number of different types of reports standard form letter form cross tab subreport mail labels top N and drill down These reports can contain multiple detail sections conditional sections and columns With version 5 0 reports can also be nested within each other The Expert s interface is user friendly and easily replaces Centura s quick report generation capability while providing a great deal more flexibility and power For example this report creation Expert can be re entered to accommodate future changes Report distribution in many shapes and sizes Seagate Software takes report distribution to new heights In add
40. rts to be exported to a static HTML file it doesn t allow any capability for publishing dynamic HTML database reports such as Oracle s Web Request Broker or Netscape s LiveWire product Since Centura s reporting tool doesn t support HTML output at all I guess something is better than nothing Using Centura s tight integration between its development and reporting tool it is possible to create HTML output with additional coding using QuickReports API but this and other possibilities will be explored in my next article But wait there s more When all said and done it s easy to see why Crystal is such a popular client side reporting tool From a stand alone reporting tool perspective Centura s reporting tool doesn t provide much competition However the critical question that remains from a Centura programmer s point of view is this To what degree can Crystal be integrated into the Centura development environment Obviously Centura s own reporting tool is going to have better integration out of the box but how much better Stay tuned CP Doug Mitchell is a Principal with American Management Systems AMS in Fairfax Virginia He has been using Centura products to help his clients develop custom client server business applications for the last six years He volunteers as a Centura Team Assist member serves as a Centura instructor presides over the Washington D C area Centura user group and has presented a
41. s from third parties like FrontEnd Systems METEX ADC and Ten Ham Informatiesystemen Scope and qualification Understanding scope and how to formulate qualified references is one of the more complicated aspects of SAL Fortunately if you stick to the principles of object oriented programming you can minimize your need to use qualified references and simplify your code The forthcoming Tomahawk release of CTD will include significant changes in this area eliminating much of the complexity that exists in SAL today However for the present it is useful to understand the various forms of qualification and how they are used or avoided In the outline there are many and varied places where you can define the elements of an application I use elements as a catch all to refer classes windows variables functions and so forth Each element has a name or identifier that you use to refer to or manipulate the element The term used in the Developers Reference manual is symbol Depending on where you are in the outline and what element you want to refer to you may have to qualify the element s symbol to help the compiler or runtime engine understand what element you are specifying The scope of a symbol is the part of the outline where you can refer to an element using just its symbol without any additional qualifications In SAL scope is linked to containership that is the scope of a symbol is anywhere within the defining element
42. t is anticipated that this form of qualification will no longer be supported The recommended migration strategy for legacy SAL code is to use late found function calls For example consider a circa SQLWindows 3 1 application with code like this Form Window frmA Functions Function Clear Form Window frmB Functions Function Clear Call hWnd Clear where hWnd is the window handle of either an instance of frmA or an instance of frmB A possible restructuring could look like this Form Window Class cFrm Functions Function Clear possibly a virtual function cFrm frmA Functions Function Clear cFrm frmB Functions Function Clear Call hWnd cFrm Clear Continues on page 12 Save Effort and Resources with Forms on Tabs Larry stani ssociating a form with a tab is a great improvement over the initial tab forms Anybody who has worked with tabs would probably agree that the user interface UI is great but has contributed to some serious problems The sole original method by which tabs worked was to have all of the children on all tabs belong to the one form that contained the tab This often led to forms with hundreds of child windows sometimes reducing resources to 10 percent or less available Another problem that crops up is managing the development of the tab form Usually all the information presented on multiple tabs is related but it often comes from different tables for different tabs
43. t on the scoping rules in that version If you have such an application I recommend you convert the app to use the present scoping rules as it is anticipated that release 4 0 scoping rules won t be supported in the Tomahawk release of CTD Reject Multiple Window Instances My preference for this property is to set it to No unchecked in CTD If you leave it as Yes or checked then when the application attempts to create multiple instances it 6 Centura Pro February 1997 Figure 1 Centura Team Developer defaults to Fully Qualified External References but SQLWindows does not terminates rather abruptly and in an unfriendly manner If I need to limit window instances I do it in code Fully Qualified External References I normally set this item to Yes or checked Unqualified external references to variables and controls complicate debugging Of course references to variables are best avoided altogether if possible as they violate encapsulation References are further discussed in the section Scoping and Qualification Unfortunately this setting has no effect on handle qualified references previously known as semi qualified references Enable Runtime Checks of External References This item is useful to set to Yes or checked during development but set to No for production releases When set to Yes the object referred to by a window handle used in a fully qualified reference is checked to ensure that it matches the identif
44. t the last four Centura conferences Contact him at doug_mitchell mail amsinc com News class browser Memorize an in memory database for optimizing application performance and the Widget Library for SQLWindows a library of user interface QuickObjects A developer version of Shape Composer is priced at 495 during its introduction To learn more contact the company at 31 20 612 3344 or fax 31 20 685 5741 The company expects its Web site at www trilogic nl to be active in February CP If your company has news about new products services clients or projects send details to 71460 3142 compuserve com or fax 818 246 0487
45. u can save the information from the form and destroy the form As part of tab processing the function TabUserRequest is called late bound from the SQLWindows code This means that if you have a function by the same name in your tab form the form that contains the tabs your version of the function will be called instead of the default version that comes with QCKTABS APL The function takes two parameters a window handle and a number Centura has implemented tab functionality within the structure of a picture window picTabs by default The window handle is that of the tab frame often named picTabs and the number is the index of the tab to which you are moving If you re experienced with tabs you ll recognize that this late bound function simply takes the place of the message TABSM UserRequest Also if for some reason program logic dictates that the user not change tabs you may call function CancelMode which will deny the user s request and leave the current tab displayed From within the TabUserRequest function see Listing 2 call the function hWnd cQuickTabs GetTop where hWnd is the window handle parameter originally passed to the TabUserRequest function Set a numeric variable say nWasIndex to that value Then call hWnd cQuickTabs GetName nWasIndex sTag This takes the tab index and gets the tag or internal name of the tab remember the unique value you specified when you set up the tabs Given this t
46. uct ForeSite is a deployment platform for Web enabled applications It offers several sophisticated features including comprehensive site management dynamic load balancing fault tolerance multi platform compatibility security and the ability to present dynamic page content through links to relational databases and other applications What does Centura gain from Cyber Editor Mark Hunter Techno Publisher Dian Schaffhauser Business Manager o matic Shelley Doyle Production Editor Superhighway Paul Gould Centura Pro is published monthly 12 times per year by Pro Publishing PO Box 18288 Seattle WA 98118 0288 POSTMASTER Send address changes to Centura Pro PO Box 18288 Seattle WA 98118 0288 Copyright 1997 by Pro Publishing All rights reserved No part of this periodical may be used or reproduced in any fashion whatsoever except in the case of brief quotations embodied in critical articles and reviews without the prior written consent of Pro Publishing Printed in the United States of America Centura Pro is a trademark of Pro Publishing Other brand and product names are trademarks or registered trademarks of their respective holders This publication is intended as a general guide It covers a highly technical and complex subject and should not be used for making decisions concerning specific products or applications This publication is sold as is without warranty of any kind either express or implied respecting
47. well Here s an example Call hWndFrame mdiMain frmCustomer tblContacts colLastName Clear Another form of fully object qualified references handles the situation where there are multiple instances of frmCustomer within mdiMain An example 8 Centura Pro February 1997 Call hWndForm mdiMain frmCustomer tblContacts colLastName Clear In this syntax the window handle has to refer to the rightmost symbol inside the parentheses As another example if you had the window handle of an instance of colLastName you would write Call hWndCol mdiMain frmCustomer tblContacts colLastName Clear Fully object qualified references are perhaps the most difficult to formulate in SAL because it s difficult to anticipate during application design exactly what is needed and how to structure the application It is anticipated that the Tomahawk release of CTD will make this form of qualification obsolete Handle qualified reference Handle qualified references originally called semi qualified references back around SQLWindows 3 x were introduced to SAL to provide a poor man s polymorphism before all the OOP additions that went into SQLWindows 4 0 This form of qualification is now obsolete and shouldn t be used It can make applications difficult to maintain and debug Currently handle qualified references are still supported to facilitate migration of older applications However in the Tomahawk release of CTD i
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