TRY/CATCH_ALL vs try/catch

Question

I've been using c++ for a while, and I'm familiar with normal try/catch. However, I now find myself on Windows, coding in VisualStudio for COM development. Several parts of the code use things like:

TRY {
    ... do stuff
} CATCH_ALL(e) {
    ... issue a warning
}
END_CATCH_ALL;

What's the point of these macros? What benefit do they offer over the built-in try/catch?

I've tried googling this, but "try vs TRY" is hard to search for.

Answer 1

It's an MFC macro:
http://msdn.microsoft.com/en-us/library/t8dwzac0%28VS.71%29.aspx

This page says they're a remnant from MFC 1.0 - use normal C++ exceptions in new code:

MFC versions lower than 3.0 did not support the C++ exception mechanism. MFC provided macros to deal with exceptions.

Answer 2

It's an artifact of Windows programming from before the days when try/catch wasn't well supported by compilers, or wasn't supported at all.

Answer 3

You'll want to keep in mind that there are 3 different kinds of exceptions when programming with Visual C++:

1. C++ exceptions
2. Structured exceptions (SEH, Windows' own exception mechanism)
3. MFC exceptions (those you mention, which are not recommended for new code but can still be used for backwards compatibility)

SEH and C++ exception mechanisms should not be mixed.

This article on MSDN has more details:

http://msdn.microsoft.com/en-us/library/x057540h.aspx