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Re: patsubst: multiline text
From: |
clemens fischer |
Subject: |
Re: patsubst: multiline text |
Date: |
Wed, 08 Sep 2010 23:45:59 +0200 |
User-agent: |
tin/1.9.6-20100313 ("Lochruan") (UNIX) (Linux/2.6.35.4-spott (i686)) |
Eric Blake wrote:
> M4 1.4.x only supports the glibc emacs flavor of regexp. M4 2.0 has
> improved regex support, allowing you to choose different flavors
> supported by glibc, such as strict posix, extended regex, and so
> forth, but still needs tweaking before it will support tunables like
> case-insensitivity.
So the non-greedy "?" postfix operator is not available below m4-2, did
I get this right?
It takes so much time to experimentally determine what works and what
doesn't, would it be possible to document the RE syntax available in
m4-1.x? Even if only a README text, it would help quite a bit.
I even tried to get this info from the source, but it contains
a sizeable chunk of regex code in lib/reg*, some of which seems to be
there for compatibility/portability, so I eventually gave up.
> M4 2.0 will allow modules, so it is conceivable that someone could add
> a PCRE module for a different regex engine. But the default will
> still be to provide only what glibc provides (even on non-glibc
> platforms, since gnulib's regex implementation mirrors glibc).
Yes, conceivable, but propably too much hassle for people who want to
publish their code in source form, compared to using hack-arounds with
vendor-supplied m4. I guess regex modules would be made and used in
house, maybe even contributed some day.
clemens