Debugging

How do I use the 4D v6/v6.5 debugger?

The 4D v6 or later debugger is described in detail in Chapter 13, Debugging, of the 4D v6.7 Language Reference Manual. The 4D v6/v6.5/6.7 debugger is the most advanced debugger in any commercial programming environment on the market today. Many users are still unaware of some of its most useful features. These include:

• You can point at any variable or expression for a moment to see a tips-style popup showing its contents. You can activate the debugger while code is running by pressing Alt (Windows) or Option (Macintosh) and clicking the mouse button (left mouse button on Windows) on 4D v6. in 4D v6.5/6.7 you must use the following key combinations:
  • Alt+Shift+Right Click on Windows
  • Control+Option+Command+Click on MacOS
  • When you execute this action, a pop-up menu listing all the processes being executed appears. You can then select the process you wish to trace. A mark is placed next to the process name in the window in which the user clicked. The processes that were unable to be traced are shown in gray.
• You can trace a running process at any time from the Process window in the design environment
• You can trace multiple processes simultaneously, each in a separate window
• If you hold down the Alt key (Windows) or the Option key (Macintosh) when choosing No Trace, 4D will resume running and will ignore any subsequent Trace commands in that process.
• You can drag the program counter (the arrow showing which line is about to be executed) up or down to change which line will be executed next.
• You can get a variety of useful options by right-clicking (Windows) or Control- clicking (Macintosh) on most things in the debugger;
• You can set a conditional break point by option-clicking in the left edge of the watch pane. 4D will present you with a dialog asking you to enter an expression that returns a Boolean. 4D will then evaluate that expression when the line with the break point is about to be executed and will stop if the expression returns true.
• The Tools menu in the Design environment has a Break List option that opens a Break List window showing all the break points set in the code. When this window is in front, a new Break List menu appears, which allows you to click on break points and enable or disable them; delete one or all break points; and to activate a Catch.
• The Break List menu's Add New Catch command allows you to activate the debugger whenever any process executes a particular command. Note that you can instead right-click (control-click on the Macintosh) on the Catch pane of the Break List window to activate a menu which allows you to choose a command to catch.
• Any Catches you create in the Break List window can have a condition associated with their activation. You add such a condition by entering an expression that returns a Boolean in the right half of the Catch pane next to the call you want to catch.

How do I prevent 4D crashing?

4th Dimension is a very stable and reliable application, but it is dependent on a number of systems to do its work. If there are any conflicts in these systems, 4D may crash.

You should try to simplify 4D's environment as much as possible. Running other applications at the same time as 4D, or using control panels and extensions that aren't related to networking (on the Macintosh) increase the likelihood that you will see a crash. On a Macintosh 4D server, you should turn off file sharing and virtual memory, since these both slow down the system and contribute to instability. If you need to share files, either use a separate computer for this task, or turn file sharing on only when it is needed.

At times, one or more of the files in the 4D folder (the "ACI" folder in v6/v6.5), located in your Windows or WinNT directory (on the PC) or inside your Preferences folder (on the Macintosh) may become corrupted. If you experience crashes, try removing the 4D folder. On Mac, you will need to enter your ID number for most 4D applications after you do this and reinstall your Expansion disks for 4D Server (make sure you are reinstalling server with the same ID number). On the PC, you will need to reinstall your network components if you are using Client/Server 4D.

Command Removing and Re-installing NCs on Windows
Command Removing and Re-installing NCs on Macintosh

You should check that you are using the same versions of 4D client and server and network components, and that any plug-ins you are using are compatible with your 4D version and operating system. Note that you should be using 4D v6 or later of any 4D plug-ins.

If you are using 4D v6 or later and your database is converted from 4D v3 or v1.5 of 4D, you should check whether you have any plug-ins installed into your structure file and remove them. (See FAQ on Plug-ins)

 

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