POE::Filter::Block(3pm) 				User Contributed Perl Documentation				   POE::Filter::Block(3pm)

NAME

       POE::Filter::Block - translate data between streams and blocks

SYNOPSIS

	 #!perl

	 use warnings;
	 use strict;
	 use POE::Filter::Block;

	 my $filter = POE::Filter::Block->new( BlockSize => 8 );

	 # Prints three lines: abcdefgh, ijklmnop, qrstuvwx.
	 # Bytes "y" and "z" remain in the buffer and await completion of the
	 # next 8-byte block.

	 $filter->get_one_start([ "abcdefghijklmnopqrstuvwxyz" ]);
	 while(1) {
	   my $block = $filter->get_one();
	   last unless @$block;
	   print $block->[0], "
";
	 }

	 # Print one line: yz123456

	 $filter->get_one_start([ "123456" ]);
	 while(1) {
	   my $block = $filter->get_one();
	   last unless @$block;
	   print $block->[0], "
";
	 }

DESCRIPTION

       POE::Filter::Block translates data between serial streams and blocks.  It can handle fixed-length and length-prepended blocks, and it may
       be extended to handle other block types.

       Fixed-length blocks are used when Block's constructor is called with a BlockSize value.	Otherwise the Block filter uses length-prepended
       blocks.

       Users who specify block sizes less than one deserve what they get.

       In variable-length mode, a LengthCodec parameter may be specified.  The LengthCodec value should be a reference to a list of two functions:
       the length encoder, and the length decoder:

	 LengthCodec => [ &encoder, &decoder ]

       The encoder takes a reference to a buffer and prepends the buffer's length to it.  The default encoder prepends the ASCII representation of
       the buffer's length and a chr(0) byte to separate the length from the actual data:

	 sub _default_encoder {
	   my $stuff = shift;
	   substr($$stuff, 0, 0) = length($$stuff) . "";
	   return;
	 }

       The corresponding decoder returns the block length after removing it and the separator from the buffer.	It returns nothing if no length
       can be determined.

	 sub _default_decoder {
	   my $stuff = shift;
	   unless ($$stuff =~ s/^(d+)//s) {
	     warn length($1), " strange bytes removed from stream"
	       if $$stuff =~ s/^(D+)//s;
	     return;
	   }
	   return $1;
	 }

       This filter holds onto incomplete blocks until they are completed.

PUBLIC FILTER METHODS

       POE::Filter::Block has no additional public methods.

SEE ALSO

       Please see POE::Filter for documentation regarding the base interface.

       The SEE ALSO section in POE contains a table of contents covering the entire POE distribution.

BUGS

       The put() method doesn't verify block sizes.

AUTHORS &; COPYRIGHTS
       The Block filter was contributed by Dieter Pearcey, with changes by Rocco Caputo.

       Please see POE for more information about authors and contributors.

perl v5.14.2							    2012-05-15						   POE::Filter::Block(3pm)