Re: proposal for Ada preprocessor

[billwolf%hazel.cs.clemson.edu@hubcap.clemson.edu (William Thomas Wolfe, 2847 )]

From tynor@prism.gatech.EDU (Steve Tynor):
> What about the cases where disabling a feature should prevent 
> 'with'ing a package? (e.g. don't 'with' a DEBUG_TRACE package 
> in a released version) - Your method will prevent calls to the 
> trace procedures, but the DEBUG_TRACE package would still be 
> linked in to the executable (ignoring potential linker optimizations 
> that might recognize that none of that package's code is actually called).

   No, in fact these linker optimizations are relied upon very heavily
   in Ada.  Consider a generic abstract data type -- the idea is to 
   provide as much functionality in that ADT as can reasonably be 
   expected to ever be required by any of the users.  Any functionality 
   which can be expressed generically is an excellent candidate to be
   included in the package.  Now if we could not rely upon these linker
   optimizations, then ADT developers would go crazy trying to keep
   5000 variations of the same package and ADT users would go crazy
   trying to select the package having exactly the set of operations
   they will use and no more.  Obviously this is ridiculous -- both
   developer and user rely instead upon the fact that the compiler/
   linker/etc will automatically trim away anything not referenced 
   by the user.  To assume otherwise is inconceivable.


   Bill Wolfe, wtwolfe@hubcap.clemson.edu