Date: Thu, 10 Aug 2006 20:06:34 +0200 (CEST) From: Oliver Fromme <olli@lurza.secnetix.de> To: freebsd-hackers@FreeBSD.ORG Subject: Re: make(1) is broken? Message-ID: <200608101806.k7AI6Y00089040@lurza.secnetix.de> In-Reply-To: <20060810211333.2d0a73fe@localhost>
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Stanislav Sedov wrote:
> Oliver Fromme wrote:
> > I think it is better not to rely on that side effect. It
> > isn't well documented and might change without notice in
> > the future.
>
> Thanks for explanation. I suppose, however, that .for behavior could
> be used rather safely for it's well documented in make(1).
I wouldn't call that side-effect "well-documented". The
manpage says:
| The iteration variable is successively set to each
| word, and substituted in the make-rules inside the
| body of the for loop.
While that description is correct, it doesn't clearly
state the side-effect of allowing nested expansion of
the loop variable within other variables, i.e. the fact
that a line VAR=${foo:M${bar}} is parsed and handled
completely differently, depending on whether "bar" is
a loop variable or a normal variable.
Well, if you like it, you're free to use that hack to
wrap your nested variable expansion in a dummy for loop.
But don't complain if it doesn't work anymore in FreeBSD 8.
:-)
> According
> to this manpage, it's not a side effect - .for loops always unrolled
> and variable substitutions occurs.
Yes, but the point is that _nested_ variable substitutions
(inside other variables) are only documented to work for
the ":S" modifier, but nowhere else. Relying on something
that's not documented is asking for trouble.
Best regards
Oliver
--
Oliver Fromme, secnetix GmbH & Co. KG, Marktplatz 29, 85567 Grafing
Dienstleistungen mit Schwerpunkt FreeBSD: http://www.secnetix.de/bsd
Any opinions expressed in this message may be personal to the author
and may not necessarily reflect the opinions of secnetix in any way.
"Python tricks" is a tough one, cuz the language is so clean. E.g.,
C makes an art of confusing pointers with arrays and strings, which
leads to lotsa neat pointer tricks; APL mistakes everything for an
array, leading to neat one-liners; and Perl confuses everything
period, making each line a joyous adventure <wink>.
-- Tim Peters
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