Hello,
I just recently discovered m4's progress toward version 2.0. There's a
*lot* to like in the feature list, and I'm glad to see the project isn't
stuck in maintenance mode.
I've been dealing a bit with macro processors lately, with some
frustration. Please consider the following as an outsider's perspective, or
a hopefully reasonable use-case scenario:
I've been looking for a macro processor to implement a LaTeX-like language
for Web design. With "classic" m4, this is impractical, because unless you
meticulously quote everything, commas in ordinary text are a pain to deal
with. I worked with a different program (GPP) for a while, as it allows
near-complete customization of the macro syntax (and even supports a
TeX-like scheme out of the box), but it lacks some of the nicer features of
m4 like patsubst() and diversions.
The new changesyntax() builtin is very enticing. I noticed that in (CVS)
m4/examples/WWW/m4lib/ there is even a LaTeX-like Web design macro language
already elaborated.
There are some pretty clear limitations to it, however. The biggest one for
me is that you cannot make the macro argument separator a multi-character
sequence, so you have to settle for
\macro{arg one, arg two, arg three}
or perhaps something like
\macro{arg one|arg two|arg three}
instead of the more LaTeX-like
\macro{arg one}{arg two}{arg three}
which is what I want, not least because it all but does away with the need
to quote the arguments.
Many of the other syntax categories can usefully be specified as
multi-character sequences, too. In fact, aside from the following
categories...
Letters
Digits
White space
Other
Active
...it seems a bit awkward to define them using a set of characters, given
that the set is nearly always of size 1. Even if you have, say, the
following hypothetical sets of size 2...
Open paren => "(["
Close paren => ")]"
...m4 won't recognize (let alone enforce) proper nesting; "foo(bar]" would
be a valid macro call. I don't see how a set-of-characters match is
well-suited for defining these sorts of syntax categories.
On a different note, may I make a feature suggestion/request? I see that
two of the syntax categories address "extended argument references." These,
from what I can tell, work the same way as standard argument references,
except for the extra bit of syntax protection---you can say e.g.
"1111${2}1111" safely.
But that wasn't obvious to me at first, and for a moment I was thinking m4
had gained support for named arguments. Which would have been a really,
really nice feature to have. Something where you could do e.g.
=> define(`foo', `The ${noun} is ${verb}.')
=> foo(noun = `fox', verb = `running')
The fox is running.
But then the order of the arguments wouldn't matter, and you could have
macros that potentially take a large number of args but only a handful in
normal use---the example that comes to mind is a BibTeX citation.
(Now, currently, you can get a similar effect by using more macros, e.g.
=> define(`foo', `The noun is verb.')
=> define(`noun', `fox')
=> define(`verb', `running')
=> foo
The fox is running.
But then you have to worry about namespace pollution/collisions with the
"argument names," especially if you favor shorter ones. Not ideal.)
Any comments on the above would be appreciated,
--Daniel
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