[Scons-users] Scons using config.h.in

[Zachary Lund]

On Tue, 2013-04-02 at 13:53 +0200, dev at mgautier.fr wrote:

> > Herm... good question :D 

> > 

> > I suppose ultimately, I'm having issues adding things like

> "#include" 

> > statements (or anything that isn't directly support in Scons) in my 

> > config header (i.e. outside of macros is the use of "typedef". If a 

> > certain type doesn't exist, create an alternative). I suppose I

> could do 

> > this using substfile like stated above... it just seems kinda round 

> > about and sloppy. 

> > 

> > It's static content so I feel like substfile is overkill and/or

> overly 

> > complicated for the task. 

> > 

> 

> 

> Hello, 

>   

> Does this (http://www.scons.org/wiki/GenerateConfig ) answer your

> problem ? 

>   

> We use it in our build system and it works pretty well. 

> 

> It should be possible for you to create a builder to automatically

> create config.h from config.h.in instead of explicitly call

> env.Command. 

>   

> Matthieu. 

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Eh, I'm going through way to much trouble for this. 

I am going to use the GenerateConfig method but I'd have to do:

#if %(HAVE_ALLOCA_H)i
#define HAVE_ALLOCA_H %(HAVE_ALLOCA_H)i
#endif

about 130 times, literally. This turns my 380 line header to 1200 lines.
I setup a regex to do this for me and it works out well, it's just
incredibly sloppy. The reason I have to do this is because the macro
cannot be defined if we don't support a feature. Setting it to 0 doesn't
work in this case because #ifdef's are used all over the place.

I'd like to eventually have it #undef anything that isn't supported but
it seems like a real pain in the ass. I really don't get why this isn't
support in Configure(). It already does this to some extent with
Define().

CMake also has something similar to this with #cmakedefine where the
above example would look like this in the template header: 

#cmakedefine HAVE_ALLOCA_H @HAVE_ALLOCA_H@

An alternative to this that's supported direclty by Scons would be nice
for the sake of convenience and a universal method.