what is a filter ? WExplain any five filters in unix

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web::scraper::filter

Web::Scraper::Filter(3pm)				User Contributed Perl Documentation				 Web::Scraper::Filter(3pm)

NAME

       Web::Scraper::Filter - Base class for Web::Scraper filters

SYNOPSIS

	 package Web::Scraper::Filter::YAML;
	 use base qw( Web::Scraper::Filter );
	 use YAML ();

	 sub filter {
	     my($self, $value) = @_;
	     YAML::Load($value);
	 }

	 1;

	 use Web::Scraper;

	 my $scraper = scraper {
	     process ".yaml-code", data => [ 'TEXT', 'YAML' ];
	 };

DESCRIPTION

       Web::Scraper::Filter is a base class for text filters in Web::Scraper. You can create your own text filter by subclassing this module.

       There are two ways to create and use your custom filter. If you name your filter Web::Scraper::Filter::Something, you just call:

	 process $exp, $key => [ 'TEXT', 'Something' ];

       If you declare your filter under your own namespace, like 'MyApp::Filter::Foo',

	 process $exp, $key => [ 'TEXT', '+MyApp::Filter::Foo' ];

       You can also inline your filter function without creating a filter class:

	 process $exp, $key => [ 'TEXT', sub { s/foo/bar/ } ];

       Note that this function munges $_ and returns the count of replacement. Filter code special cases if the return value of the callback is
       number and $_ value is updated.

       You can, of course, stack filters like:

	 process $exp, $key => [ '@href', 'Foo', '+MyApp::Filter::Bar', &baz ];

AUTHOR

       Tatsuhiko Miyagawa

perl v5.14.2							    2009-03-24						 Web::Scraper::Filter(3pm)

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