- The ability to set breakpoints, and step through code in the IDE debugger.
- The ability to measure code coverage of running code.
- Syntax errors are reported in the Curl IDE in debuggable applets, where the developer may easily click on the error and navigate to the offending code. In non-debuggable applets they are only reported in the applet's main window.
- Lazy compilation is disabled in debuggable applets. In non-debuggable applets, functions are not compiled (and errors not detected) until they are first used, which may not happen until well after the application has been started.
- Compiler optimizations like function inlining and register allocation are disabled in debuggable applets.
- The Curl performance profiler can report information about source lines in debuggable applets; otherwise only function-level information is available. However, because optimizations are disabled, profiling debuggable applets may produce significantly different results than non-debuggable ones.
The principle disadvantage to making your applets debuggable is that the combination of disabled optimizations and insertion of extra noop instructions to support debugging will result in slower code, and in some cases debuggable applets may be dramatically slower. In these cases, the developer may want to be applet to run the same applet debuggable when using debugger or coverage features, but otherwise use a non-debuggable version.
At least up through version 7.0 of the RTE, debuggability of Curl applets in is controlled solely by the list of directories listed in the Debugger pane of the Curl RTE Control Panel. When the RTE starts a new applet, it consults this list to see if the applet should be made debuggable. If the applet's starting URL is in the specified directory, it will be made debuggable.
So for developers to run the same applet with different debuggability settings, they must either add and remove entries to the debuggability settings in the Control Panel every time they want to run the applet differently or they find a way to run the same applet from different paths. The latter is obviously preferrable. On linux (and Mac OSX) this can easily be accomplished by creating symbolic links using the 'ln' command. For instance, on the linux machines I use at work, I have started putting all of my Curl projects in a subdirectory named 'ws' (short for workspace), and have made a symbolic link named 'non-debug-ws' to the 'ws' directory, so that I can configure my debuggability settings to use paths beginning with "file:///u/cbarber/ws/" to load applets from the source with debuggability enabled, and those beginning with "file:///u/cbarber/non-debug-ws/" to run non-debuggable versions.
On Windows, however, this is not so easy, since there is no equivalent command in Windows nor is there any way to accomplish the same thing in the Explorer UI. It turns out that it is indeed possible to create the equivalent of a unix symbol link on Windows NTFS file systems -- the default file system used by Windows NT and later -- a NTFS "junction point", but this ability is only available in low-level system programming APIs. Fortunately, there are a number of open source solutions that give you the ability to create them. The one that I favor is an open-source shell extension called NTFS Link, which adds entries for creating NTFS hardlinks and junction points to the Windows Explorer's "New" submenu. The one gotcha is that you must be careful not to delete junction points in the explorer until you have unlinked it from its target directory, or else you will end up deleting the target directory contents as well!
P.S. In case it is not already obvious, that the debuggable path is the same as the path you use in your development environment. The non-debug path does not have to be reflected in your development environment since it is not expected to cause breakpoints to be triggered, and so on.
