Re: magic variables for included fragments

[Akim Demaille]

Le 10 déc. 08 à 21:14, Ralf Wildenhues a écrit :

> Hi Akim,

Hi!

> * Akim Demaille wrote on Wed, Dec 10, 2008 at 10:21:50AM CET:
>
> > Ok.  And these makes can be fooled to implement the feature by  
> > computing
> > the file name at make-time instead of passing a litteral?
>
> Not quite sure I follow here yet.  Yes, I think it is possible to use
> macro names in @am__include@ statements (we already use $(DEPDIR)).   
> But
> what would it buy us?  'make' typically requires all unconditionally
> included files to be present, before it thinks of taking any further
> action.
>
> Thanks for enlightening me.

I was wandering if we could find a means to change the argument of  
"include" to implement the silent include feature, for instance by  
passing "/dev/null" when the file does not exist, or maybe during the  
initial build, I don't know.  If all the Make implementations provide  
something like $(shell...) we could do that.  But of course the answer  
is "they don't" :)

Just thinking aloud about a means to workaround the lack of  
universality of "-include".  After all, Automake's "if" is implemented  
on top of a hack :)

The question is: how can we have Make check for the presence of a file.