hint for improved keyword substitution

Here's a modest proposal for svn 1.5 final.
the $PROPERTY: VALUE $ syntax is a nightmare in C/C++ sources.

I'd like to have some directive that replaces the FIRST occurrence of
a user-specified keyword in the following lines.
imagine something like:

//
// this is a comment
//
// $Revision: MY_DUMMY_KEYWORD $
//
// svn will leave intact the line above and replace the first
occurrence of the keyword with its value...
//

#define SVN_REVISION_NUMBER MY_DUMMY_KEYWORD

int main()
{
}

Hope someone is listening... :)
MH