X-Git-Url: http://git.shadowcat.co.uk/gitweb/gitweb.cgi?a=blobdiff_plain;f=pod%2Fperlfilter.pod;h=51cd8ced75331761f668c145e6aa612a3c9a7646;hb=a5c75c1d181494e06a58988f267a8b3d081df483;hp=c3c83153adfaf643b415846f00cf8f529ad23bd2;hpb=ee8c7f5465f003860e2347a2946abacac39bd9b9;p=p5sagit%2Fp5-mst-13.2.git diff --git a/pod/perlfilter.pod b/pod/perlfilter.pod index c3c8315..51cd8ce 100644 --- a/pod/perlfilter.pod +++ b/pod/perlfilter.pod @@ -2,7 +2,6 @@ perlfilter - Source Filters - =head1 DESCRIPTION This article is about a little-known feature of Perl called @@ -528,7 +527,7 @@ blocks get included. Once you can identify individual blocks, try allowing them to be nested. That isn't difficult either. -Here is a interesting idea that doesn't involve the Debug filter. +Here is an interesting idea that doesn't involve the Debug filter. Currently Perl subroutines have fairly limited support for formal parameter lists. You can specify the number of parameters and their type, but you still have to manually take them out of the C<@_> array @@ -552,12 +551,31 @@ useful features from the C preprocessor and any other macro processors you know. The tricky bit will be choosing how much knowledge of Perl's syntax you want your filter to have. +=head1 THINGS TO LOOK OUT FOR + +=over 5 + +=item Some Filters Clobber the C Handle + +Some source filters use the C handle to read the calling program. +When using these source filters you cannot rely on this handle, nor expect +any particular kind of behavior when operating on it. Filters based on +Filter::Util::Call (and therefore Filter::Simple) do not alter the C +filehandle. + +=back + =head1 REQUIREMENTS The Source Filters distribution is available on CPAN, in CPAN/modules/by-module/Filter +Starting from Perl 5.8 Filter::Util::Call (the core part of the +Source Filters distribution) is part of the standard Perl distribution. +Also included is a friendlier interface called Filter::Simple, by +Damian Conway. + =head1 AUTHOR Paul Marquess EPaul.Marquess@btinternet.comE