Item6825: RE error in Load.pm

s/(\$TWiki::cfg{[[A-Za-z0-9{}]+})/eval $1||'undef'/ge;

There're three brackets, I think it would be:

s/(\$TWiki::cfg{[A-Za-z0-9{}]+})/eval $1||'undef'/ge;

-- TWiki:Main.PhillipHuang - 2011-12-14

Thanks! Confirmed, needs to be fixed.

-- TWiki:Main.PeterThoeny - 2011-12-14

This is now fixed in svn trunk and TWiki-5.1 branch. Thanks Phillip!

Changes:

--- Load.pm   (revision 22272)
+++ Load.pm   (working copy)
@@ -109,7 +109,7 @@
         if (ref($_) eq 'HASH') {
             expand(\%$_);
         } else {
-            s/(\$TWiki::cfg{[[A-Za-z0-9{}]+})/eval $1||'undef'/ge;
+            s/(\$TWiki::cfg{[A-Za-z0-9{}]+})/eval $1||'undef'/ge;
         }
     }
 }
@@ -129,7 +129,7 @@
 =cut
 
 sub expandValue {
-    $_[0] =~ s/(\$TWiki::cfg{[[A-Za-z0-9{}]+})/eval $1||'undef'/ge;
+    $_[0] =~ s/(\$TWiki::cfg{[A-Za-z0-9{}]+})/eval $1||'undef'/ge;
 }
 
 =pod

-- TWiki:Main.PeterThoeny - 2011-12-14

Line ' s/(\$TWiki::cfg{[A-Za-z0-9{}]+})/eval $1||'undef'/ge;' is seemed to expand $TWiki::cfg{}{}deeply, I think it does not need 'undef' because replace only take effect when find $1, in another word, $1 is always existing when matched. Perhaps would remove undef and using '' s/(\$TWiki::cfg{[A-Za-z0-9{}]+})/$1/ge;"

-- TWiki:Main.PhillipHuang - 2011-12-15

Probably could do that. A change like this needs to be tested carefully. It works now, "if it is not broken, don't fix it".

-- TWiki:Main.PeterThoeny - 2011-12-14

Actually, the eval is needed. Take this example:

$TWiki::cfg{DataDir} = '/var/www/twiki/data'
$TWiki::cfg{DebugFileName} = '$TWiki::cfg{DataDir}/debug.txt';

The second variable contains a variable embedded in the value. It needs to be expanded, so that as a result we have $TWiki::cfg{DebugFileName} = '/var/www/twiki/data/debug.txt';

So, the regular expression (the one fixed) looks for $TWiki::cfg{...} patterns and evaluates them. The eval will fail in case the variable does not exist. For this case we have the 'undef'.

-- TWiki:Main.PeterThoeny - 2011-12-14

I see. Thanks Peter,

-- TWiki:Main.PhillipHuang - 2011-12-16