* HACKING: Update note about use of `$#' in m4 macros.

diff --git a/ChangeLog b/ChangeLog
index 6610ca48b4ac5764b057726b5cdf2875bc3570a2..27487ac8b66fd48bf3d32dadefaa13607f787baf 100644 (file)
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,7 @@
+2005-10-27  Stepan Kasal  <kasal@ucw.cz>
+
+       * HACKING: Update note about use of `$#' in m4 macros.
+
 2005-10-27  Ralf Wildenhues  <Ralf.Wildenhues@gmx.de>
 
        * tests/tagtrace.test: Allow `$AUTOCONF' to contain arguments.

diff --git a/HACKING b/HACKING
index 569a18c21b1ab8183443511a1218d1166157e089..c1f9ecdf6d8996c06a1a41a7d33248c1650a9547 100644 (file)
--- a/HACKING
+++ b/HACKING
@@ -241,8 +241,11 @@ yyyy-mm-dd  Name of Author  <email@address>  (tiny change)
    $ECHO ".."          for strings without leading hyphen,
    $ECHO "X.." | $Xsed otherwise.
 
-* Do not use the number of macro arguments `$#' in public macros;
-  AU_ALIAS may change it.
+* The Autoconf manual says that giving an empty parameter is equivalent
+  to not giving it at all.  (In particular, the Autoconf manual doesn't
+  explain that "FOO()" is calling macro FOO with one empty parameter.)
+  To prevent misunderstanding, we should use m4_ifval to check whether
+  a parameter is empty, and not $# to check for the number of parameters.
 
 
 9. Abstraction layers in libltdl