[Mimedefang] blocked file types in text file

Steffen Kaiser skmimedefang at smail.inf.fh-bonn-rhein-sieg.de
Tue Sep 20 02:11:39 EDT 2005


On Mon, 19 Sep 2005, John Rudd wrote:

> Right, that's the same as what $& is doing: it's telling you what part of the

There is a large performance penalty using the special $` $' $& variables, 
because if you use those variables anywhere in the code, they are 
propagated for each regex, which is not so for $1 variables.

There was a thread some time ago claiming that e.g. SpamAssassine's huge 
amount of regex's drop the performance significantly.

($& is not so problematic than $`and $', if I remember correctly. Perl 
developers have made the same quirk, see "perldoc English" last 
paragraphe:

"PERFORMANCE
        This module can provoke sizeable inefficiencies for regular expres-
        sions, due to unfortunate implementation details.  If performance 
mat-
        ters in your application and you don't need $PREMATCH, $MATCH, or
        $POSTMATCH, try doing

           use English qw( -no_match_vars ) ;

        .  It is especially important to do this in modules to avoid 
penalizing
        all applications which use them."
)

Bye,

-- 
Steffen Kaiser



More information about the MIMEDefang mailing list