How to “scan” the full list of currently-installed VCL components

Question

I still haven\'t found a truly satisfactory answer to this question, and am now considering rolling my own. I have ModelMaker and GExperts, and neither seems to load the co

Answer 1

Unfortunately, the code implementing the RegisterClass mechanism is hidden in Classes implementation section.

If you need this for getting the list of components installed in the IDE, you can write a design package, install it into the IDE and use IOTAPackageServices in ToolsAPI unit. This will give you the list of installed packages and their components.

Note: You'll have to add designide.dcp to your 'requires' clause to be able to use Delphi's internal units like ToolsAPI.

A bit more work but a more generic way would be to enumerate all loaded modules. You can call GetPackageInfo (SysUtils) on a package module to enumerate contained unit names and required packages. However this will not give you a list of classes contained in the package.

You could enumerate the package's list of exported functions (e.g. with TJclPeImage in the JCL) and search for those named like this:

@@@

for example: '@System@TObject@'.

By calling GetProcAddress with the function name you get the TClass reference. From there you can walk the hierarchy using ClassParent. This way you can enumerate all classes in all packages loaded in a process running a Delphi executable compiled with runtime packages (Delphi IDE, too).