Re: An autoconf tutorial.

[Andre Caldas]

Hello, Ed!

	There are many things that are considered "bad practice". There are 
many things that are "old deprecated" ways to do things.

	For example, using the file name "configure.in" is outdated. You should 
use "configure.ac".
	I guess (I don't really know) that the reason for this is that "in" is 
supposed to mean "input". "configure.ac" is an input file to generate a 
"configure" script. This, however, assumes you have only one program 
processing the inputs:
                configure.ac ---> configure
if you have something like this
                something.bb ---> something.aa ---> something,
the extension "in" makes no sense. It is much better to name the file 
after the program that is supposed to process it: autoconf ---> ac, 
aumotmake ---> am.


Ralf Wildenhues wrote:
> Hi Ed,
>
> Please keep the mailing list copied, this is interesting for others as
> well.  Thank you.
>
> * E. Rosten wrote on Wed, May 25, 2005 at 10:53:13AM CEST:
>
> > On Wed, 25 May 2005, Ralf Wildenhues wrote:
> >
> > > * E. Rosten wrote on Mon, May 23, 2005 at 06:59:05PM CEST:
> > >
> > > | M4 arguments are quoted with [ and ]. There is NO WAY to escape these,
> > > | however, you can change the quoting using:
> > > |
> > > |                          changequote(<<,>>)
>
> *snip*
>
> > > Please don't encourage use of changequote.
> >
> > How come?
>
>
> Documented in
>   info Autoconf 'Changequote is Evil'
or
http://www.gnu.org/software/autoconf/manual/autoconf-2.57/html_node/autoconf_94.html

It is at least as bad as changing the value of a global variable that is 
supposed to be constant.


> > > Rather quadrigraphs.

I didn't know about it. Its nice beeing on the mailing list. :-)


> > What are they (I haven't encountered them)? Is it a way of entering [ and 
> > ] without [ and ] actually appearing?
>
>
> Documented in
>   info Autoconf Quadrigraphs
or
http://www.gnu.org/software/autoconf/manual/autoconf-2.57/html_node/autoconf_95.html

Ed, it would be very nice if you could put "warnings" in your tutorial 
telling people to avoid every "bad practice" you know about. When I 
started using autoconf, I used to visit some tutorial websites. Some 
would say "do like this", and others would say "never do this" for the 
same thing. It is very confusing. There is already a lot of information 
to memorize. One ends up not knowing what you should or shouldn't do. 
You never know what source of information you should trust. A good 
tutorial IMHO would say:

"You will see that in a lot of places the macro AC_XXX is used like 
[this or that]. This is not considered 'good practice' because of [this 
and that]. The correct aproach is [this and that]."

This way one knows exactly what source of information to trust. Of 
course not everybody agrees in what is or isn't "good practice". If you 
are aware of such divergencies, it would be nice to have a comment about 
it, too.

The important thing to learn about autotools, is not how to get the job 
done. But how to do it in a clean way.

Please, keep doing the good work. And be open to criticism. This way, 
you will not only help lots of people, but probably the one who will 
learn most is going to be you.

Andre Caldas.