TCL and VA
|Column Tag:||Getting Started
TCL and Visual Architect, Part 1
By Dave Mark, MacTech Magazine Regular Contributing Author
Note: Source code files accompanying article are located on MacTech CD-ROM or source code disks.
Last month we took a first look at PowerPlant and Constructor, the class library and interface construction tool that comes with every copy of CodeWarrior from Metrowerks. This month, well cross the aisle and take a look at Symantecs counterparts, the Think Class Library (better known as the TCL) and Visual Architect (VA).
About Symantec C++
When you buy CodeWarrior, you get a PowerPC compiler and a separate 68K compiler. Version 8.0 of Symantec C++ takes a slightly different approach. Version 8.0 comes with a complete rewrite of the THINK Project Manager, known as the Symantec Project Manager (SPM). Though the SPM can run on both 68K and PowerPC platforms, it is currently only capable of generating PowerPC native code. To generate 68K code, youll need to use version 7.0.4 of the THINK Project Manager (TPM) (its installed in the same tree as SPM, automatically, when you install SC++ 8.0). The 8.0 CD includes both SPM and TPM. According to Chris Prinos (a Symantec engineer and one heckuva nice guy), both of these environments are source code compatible. In other words, you can maintain a single source code base and compile it with 7.0.4 if you want 68K code and 8.0 to generate PowerPC code. I havent tested this theory yet, and Id like to get feedback from you about compiling across environments.
The SC++ Users Guide that comes with 8.0 includes some tutorials showing you how to create a user interface using Visual Architect and how to implement that interface using the TCL. One of the tutorials (Users Guide, Chapter 14) is very similar to the PowerPlant example we went through last month and is perfect for this months column.
If you have a copy of the Users Guide, youll see that Ive split the Chapter 14 tutorial into two parts. This month, well get to know Visual Architect and use it to create a basic TCL project. Sorry to split the column in two, but there just isnt enough space to do the whole thing in one swell foop.
Create A New Project
In last months column, we created our PowerPlant project by duplicating an existing project. We could have taken advantage of PowerPlants canned project models to create the new project instead. Thats the exact approach well use to create our new TCL project.
Create a new folder (anywhere outside the Symantec C++ for Power Mac folder) named Button .
Go into the Symantec C++ for Power Mac folder and double-click on the Symantec Project Manager application. If you dont have access to a PowerMac, use the THINK Project Manager instead and follow along as best you can (Either way, you will be using the same version of Visual Architect).
The Symantec Project Manager (also known as SPM) will prompt you for the name of a file to open.
Click on the New Project button.
SPM will prompt you to name your new project and to select the project model that will be used to produce the project.
Type in the name Button.Π and select VA Application from the popup menu, then click the Save button.
The Button.Π project window will appear (See Figure 1). The file Project Resources.rsrc contains the basic set of resources used for a TCL application. Once you get through this column and get your program working, take some time to explore the resources that come with the generic VA project. For now, well just use the resources weve got.
Figure 1. The Button.Π project window.
Heres a quick tour of the project window. The Headers popup presents you with a list of all the header files accessed by your project. A files headers are not added to the list until the file is compiled. If you control-click on the popul, the list will also include the headers from any precompiled headers used by the project.
The second popup, labeled Options, lets you apply different sets of preferences to your project. To build a custom options set, select Options... from the Project menu. Make changes to the various option panes, then select Save Options As... from the Options: popup menu to give your current settings a name. This new set is now available from the Options popup in the project window. While it is nice to be able to switch between options within a project, it sure would be nice to be able to create a master set of options for all projects, or to create several sets and export them to other projects. Maybe in 8.0.4? By the way, all the options are recordable, so you can create a script to set up a projects options.
If you click on one of the four column headers, a small down-arrow will appear to the left of the column label. Once the arrow is in place, click on it again to change the sorting order of the project files. For example, clicking on the word Code lets you order the files by object code size, switching between low to high or between high to low.
The check-mark column corresponds to CodeWarriors touch popup menu. It lets you mark a file as either needing to be compiled or (assuming it was compiled at some point) as already compiled. If you upgrade to 8.0.3, the Make status is shows for groups as well as for individual files.
The file Visual Architect.rsrc contains special resources used by Visual Architect to define your programs views and panes within views. Though you can browse this file using your favorite resource editor, there is really no reason. Leave this resource file to Visual Architect!
The group of files labeled Runtime Libraries contains the support libraries SPM needs to build your application. The group labeled THINK Class Library contains the source code that implements all of the TCL classes. In last months program, we added the PowerPlant classes we needed to our project as we identified them. The VA Application project model adds a complete set of TCL files to the project. Open the THINK Class Library group (click on the triangle to the left of the group) and look through the TCL files. The up side to this approach is that youll never have to search for the TCL classes youll need. Theyll already be part of your project. The down side of this strategy is that the project file will have a base size (when compiled) of about 10 megs (yikes!). Of course, if youve got a gigabyte hard drive, 10 megs isnt that much space. With the objects removed, your project folder will weigh in at about 165K.
Using the shared library project model saves space because the TCL portion is a separate sub-project that gets shared among all the projects that use it. You still retail full debugging capabilities, and both the TCL project and your application project can be open at the same time (the SPM allows you to have any number of projects open, unlike the TPM or Code Warrior).
Opening Visual Architect
At this point, your project lacks a core, that is, the set of functions (like main()) that drive your application. The source code files containing these functions will be generated by Visual Architect once you define your user interface. Thats exactly what youll do now.
Figure 2. The main VA window showing the views in Visual Architect.rsrc.
In the Button.Π project window, double-click on the file named Visual Architect.rsrc.
SPM will launch Visual Architect, opening the copy of Visual Architect.rsrc in the folder Beeper . The window that appears (Figure 2) lists the views defined in this file. By default, the file comes with a single view named Main.
Double-click on the word Main in the view window.
A window will appear showing the panes in the view named Main.
Select Show Item Numbers from the Options menu.
Item numbers will appear next to each of the two window panes (Figure 3). The Main view features a PICT pane (1) and a static text pane (2). Think of the view as some type of window and the list of panes as an item list just like the DITL in a dialog.
Figure 3. The Main view, showing each of the two panes.
Item numbers are turned on.
If you double-click on a pane (or single-click on a pane and select Pane Info... from the Pane menu) a pane browsing window will appear. Figure 4 shows the pane browser for the static text pane. The browser lets you specify a name for the pane, as well as its boundaries (you can also set the boundaries by dragging the panes handle in the view window). The bottom half of the browser lists the panes class, as well as each of the classes that class is derived from. Clicking on the triangle to the left of a class name gives you access to that classes data members. If youve ever used the TCL before, the data members will probably look familiar to you.
Figure 4. The browser for the static text pane.
Change the hText field in the CEditText class to something like
Select Try Out from the View menu.
A window will appear emulating the current view (in this case, Main). Play with the window. Resize it. Scroll it. Drag it around the screen. When you are done, just click the close box and it will go away.
Our next step is to build an application based on the Main view. Well ask Visual Architect to generate the source code that implements this view and to add that code to our project.
Select Generate All... from the Symantec Project Manager menu. The SPM menu is the diamond-shaped menu (square if you are using THINK Project Manager) immediately to the right of the Windows menu.
If the Generate All... item is disabled, try closing the front-most window. The item is disabled if the front-most window is a pane info window.
When prompted to save your changes, click the OK button.
Once you click OK, a fancy color cursor will appear and Visual Architect will go to town, generating all the code your project needs to implement the Main view. Lets take the view for a spin.
Back in the Symantec Project Manager
Switch back to the Symantec Project Manager and take another look at the project window. Notice that a new group, named Source, has been added to the project.
Click on the triangle to the left of the group Source.
Figure 5 shows the new, updated project window. Seven new files have been added to the project. Two of these, x_CApp.cp and x_CMain.cp, are off limits to you. Dont mess with these files (feel free to look them over - just dont change anything). If you go back into Visual Architect and make changes to Visual Architect.rsrc, then select Generate from the SPM menu, VA will generate new versions of these x_ files. As youll see, the x_ files contain member functions that youll override in the non-x_ files. For example, the file x_CMain.cp contains the source code that implements the Main view. The file CMain.cp contains member functions that override the member functions in x_CMain.cp. Make your changes to CMain.cp. Leave x_CMain.cp alone.
Symantec calls these x_ files lower layer files and the non x_ files upper layer files.
Figure 5. The Button.Π project window with the new source code added.
As you add more views to your VA file, VA will generate a pair of .cp files for each new view. If you add a view called ButtonDialog, VA will generate the files CButtonDialog.cp and x_CButtonDialog.cp.
The file CSaver_CMain.cpp was generated because the useFile checkbox in the view info window for Main was checked. Checking this checkbox tells VA that a file is to be associated with this view. The class CSaver_CMain contains the functions that save and restore this file.
The file main.cp contains the projects main() function.
Select Run from the Project menu.
If the item reads Run With Debugger instead of Run, press the option-key while the Project menu is still down and the item name will change to Run. This is cool to watch.
The file References.cp forces references to all the TCL classes and keeps the linker from linking out classes that are not referenced in the code, but are instantiated at run time. For example, there is a function called new_by_name() that takes, as a parameter, a class name embedded in a quoted string. Since the compiler doesnt recognize the class name (since its represented as a string instead of an identifier), it doesnt reference the class and the linker might link that class out. Visual Architect uses new_by_name_() to turn its resources into objects at run time. The set of classes Visual Architect uses to represent views and panes, therefore, must not be linked out. Thats why they are all listed in References.cp. Basically, leave this file alone, unless you need to add your own classes to it. Well do that in a future issue.
If you get an Out of Memory error, you may not have enough RAM on your machine. Try quitting all your open apps, including Visual Architect and SPM, then relaunch SPM and try again. If that doesnt work, pick up a copy of RAM Doubler. (Get the special Symantec Debugger-friendly version of 1.5.2. You can download the patch anywhere RAM Doubler is supported.)
You may also run out of room on your hard drive, since the project will take up about 10 megs of space and the application another meg. If you are worried about space, stop the compile by typing command-period and start deleting.
Once SPM starts to compile your project, go get a Fresca, take a shower, read your email, whatever. Even on a PowerMac 8100, this will take a while. SPM will compile all the new source code, along with all of the TCL. There should be approximately 157 files to update. Once everything compiles, SPM will create an application (called Button.Π.pef) and run it. A window will appear that displays the Main view. Play with the window. Resize it, scroll it, and close it if you like. Select New from the File menu to create additional Main view windows.
Till Next Month...
In next months column, well go back to Visual Architect and add a second view to our project. This view will consist of a dialog box with an editable text field and a few buttons. Well also add a button to the Main view that will bring up the ButtonDialog view. Finally, well ask Visual Architect to regenerate the source code, then go back into the Symantec Project Manager, and modify the source code to account for the changes we made in VA.
In the meantime, you may want to check your neighborhood bookstore for a book called Mastering the THINK Class Library by Richard Parker. The book just came out, and really does a great job of presenting the TCL from stem to stern. Way to go, Rich!
See you next month...