strange preprocessor stuff

[Carl Ollivier-Gooch]

Jason Kraftcheck wrote:
> iBase.h, iMesh.h, and iGeom.h all appear to contain the following
> preprocessor statements:
> 
>   #ifndef ITAPS
>   #define ITAPS
>   #endif
> 
> This is a really generic name for a preprocessor variable.  It will have the
> side effect of stripping all instances of the token 'ITAPS' from any code
> that includes our headers.  One particularly case encountered by someone at
> UWisc was as follows:
>   The directory in which to search for a test file is specified to the
>     test code at compile time with a preprocessor macro: -DSRCDIR=...
>   The code does something like:
>     const char* input_file = STRINGIFY(SRCDIR) "/input.vtk";
> 
> If the user has the source installed in a location such that one of the
> components of the path is 'ITAPS' (or in this case 'ITAPS-src'), then the
> preprocessor will remove the 'ITAPS' string from the path, causing the test
> to fail because it cannot load the input file.
> 
> I cannot find anywhere where this preprocessor macro is used.  Does anyone
> know why we have this in the headers?  Can it be removed?  Or if not, can it
> be renamed to something like '_ITAPS_INTERFACE'?

The reason for having -something- like this -somewhere- is so that an 
implementation can choose to compile things differently when it's not 
using ITAPS.  Since my implementation does this, it's entirely possible 
that I started the whole thing.  Changing the name to something sensible 
would be a good idea, though.  Maybe _ITAPS_iBase, _ITAPS_iMesh, etc?

Carl

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Dr. Carl Ollivier-Gooch, P.Eng.                   Voice: +1-604-822-1854
Associate Professor                                 Fax: +1-604-822-2403
Department of Mechanical Engineering             email: cfog at mech.ubc.ca
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