Re: magic variables for included fragments

[Ralf Wildenhues]

* Akim Demaille wrote on Thu, Dec 04, 2008 at 09:30:45AM CET:
> Le 3 déc. 08 à 20:58, Ralf Wildenhues a écrit :
>>
>> A while ago (I'm sure it's been more than a couple of years now),
>> ventured at changing depout.m4 to lift this limitation.  I did have
>> something working back then, but it required invoking `make' at
>> config.status time.  I dropped this idea as being unsuitable in the
>> presence of bugs (e.g., if `make' reinvokes configure, then there
>> can be an endless loop).  Maybe I should go back and look again,
>> for example writing out a separate makefile could help...
>
> I have a silly question, but...  is it really known for a fact that some 
> Make out there do not support "include if it exists"?

This question is not relevant to the problem.  Automake requires some
'make'-provided inclusion mechanism to work, otherwise dependency
tracking will not work.  What is the question is: do we need to use an
inclusion mechanism that fails if the file to be included does not exist
yet?  In general, the answer is "yes", because there are make
implementations that provide no other.  And even with those that do,
like GNU make, one would not want to hide problems where the included
snippets have buggily not been included as needed.

> The true problem 
> is that this is handled by config.status instead of Make itself.

Well, yes, but 'make' does not portably provide the means to fix this
situation.

> While at it, I have another portability question: are there (alive)  
> shells known not to support () for case patterns?
>
> case $host in
>   (*win*) abort;;
>   (*)     dance;;
> esac

Yes, Solaris /bin/sh for example.

Cheers,
Ralf