According to Chris Penev on 2/19/2010 8:56 PM: > Thanks for the report. Yes, double-quoting the first argument of > translit > would make the macro more robust. But this particular example was drawn > from a real-life example (on the gnulib list), where single-quoting was > sufficient for that context, under the assumption that no one will > use the > macro on a C function name that collides with a macro name. So I'm > debating between changing the example in situ, vs. adding a link to > another section in the final chapter on improved examples, to further > discuss that issue.
I want to get m4 1.4.14 out the door, so I went ahead and wrote this patch. I went with the in-place improvements. Thanks again for the report, which implies you were carefully reading the manual. -- Eric Blake ebl...@redhat.com +1-801-349-2682 Libvirt virtualization library http://libvirt.org
From bb29a1dc5aa04da98c1ea57082d4151ed8691b1c Mon Sep 17 00:00:00 2001
From: Eric Blake <ebl...@redhat.com>
Date: Wed, 24 Feb 2010 16:20:45 -0700
Subject: [PATCH] Improve parsing example.
* doc/m4.texinfo (Input processing): Double-quote argument to
translit, for robustness.
* THANKS: Update.
Reported by Chris Penev.
Signed-off-by: Eric Blake <ebl...@redhat.com>
---
ChangeLog | 8 ++++++++
doc/m4.texinfo | 15 +++++++++------
2 files changed, 17 insertions(+), 6 deletions(-)
diff --git a/ChangeLog b/ChangeLog
index 84799d0..9c3e8f7 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,11 @@
+2010-02-24 Eric Blake <ebl...@redhat.com>
+
+ Improve parsing example.
+ * doc/m4.texinfo (Input processing): Double-quote argument to
+ translit, for robustness.
+ * THANKS: Update.
+ Reported by Chris Penev.
+
2010-01-29 Eric Blake <e...@byu.net>
Document upcoming release.
diff --git a/doc/m4.texinfo b/doc/m4.texinfo
index aec1d6a..db7aff4 100644
--- a/doc/m4.texinfo
+++ b/doc/m4.texinfo
@@ -1268,13 +1268,15 @@ Input processing
to shell scripts, can be visually unappealing), and fixes the quoting
issues so that the capitalization occurs when the macro
@samp{gl_STRING_MODULE_INDICATOR} is invoked, rather then when it is
-defined.
+defined. It also adds another layer of quoting to the first argument of
+...@code{translit}, to ensure that the output will be rescanned as a string
+rather than a potential uppercase macro name needing further expansion.
@example
changequote([,])dnl
define([gl_STRING_MODULE_INDICATOR],
[dnl comment
- GNULIB_[]translit([$1], [a-z], [A-Z])=1dnl
+ GNULIB_[]translit([[$1]], [a-z], [A-Z])=1dnl
])dnl
gl_STRING_MODULE_INDICATOR([strcase])
@result{} GNULIB_STRCASE=1
@@ -1283,7 +1285,7 @@ Input processing
The parsing of the first line is unchanged. The second line sees the
name of the macro to define, then sees the discarded @sa...@key{nl}}
and two spaces, as before. But this time, the next token is
-...@samp{[dnl comm...@key{nl}@ @ GNULIB_[]translit([$1], [a-z],
+...@samp{[dnl comm...@key{nl}@ @ GNULIB_[]translit([[$1]], [a-z],
[A-Z])=1...@key{nl}]}, which includes nested quotes, followed by
@samp{)} to end the macro definition and @samp{dnl} to skip the
newline. No early expansion of @code{translit} occurs, so the entire
@@ -1300,10 +1302,11 @@ Input processing
not affect output. Then the token @samp{translit} is encountered.
This time, the arguments to @code{translit} are parsed as @samp{(},
-...@samp{[strcase]}, @samp{,}, @samp{ }, @samp{[a-z]}, @samp{,}, @samp{ },
+...@samp{[[strcase]]}, @samp{,}, @samp{ }, @samp{[a-z]}, @samp{,}, @samp{ },
@samp{[A-Z]}, and @samp{)}. The two spaces are discarded, and the
-translit results in the desired result @samp{STRCASE}. This is
-rescanned, but since it is not a macro name, it is output literally.
+translit results in the desired result @samp{[STRCASE]}. This is
+rescanned, but since it is a string, the quotes are stripped and the
+only output is a literal @samp{STRCASE}.
Then the scanner sees @samp{=} and @samp{1}, which are output
literally, followed by @samp{dnl} which discards the rest of the
definition of @code{gl_STRING_MODULE_INDICATOR}. The newline at the
--
1.6.6.1
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