POE::Filter::Grep - phpMan

NAME
    POE::Filter::Grep - select or remove items based on simple rules

SYNOPSIS
      #!perl

      use POE qw(
        Wheel::FollowTail
        Filter::Line Filter::Grep Filter::Stackable
      );

      POE::Session->create(
        inline_states => {
          _start => sub {
            my $parse_input_as_lines = POE::Filter::Line->new();

            my $select_sudo_log_lines = POE::Filter::Grep->new(
              Put => sub { 1 },
              Get => sub {
                my $input = shift;
                return $input =~ /sudo\[\d+\]/i;
              },
            );

            my $filter_stack = POE::Filter::Stackable->new(
              Filters => [
                $parse_input_as_lines, # first on get, last on put
                $select_sudo_log_lines, # first on put, last on get
              ]
            );

            $_[HEAP]{tailor} = POE::Wheel::FollowTail->new(
              Filename => "/var/log/system.log",
              InputEvent => "got_log_line",
              Filter => $filter_stack,
            );
          },
          got_log_line => sub {
            print "Log: $_[ARG0]\n";
          }
        }
      );

      POE::Kernel->run();
      exit;

DESCRIPTION
    POE::Filter::Grep selects or removes items based on simple tests. It may
    be used to filter input, output, or both. This filter is named and
    modeled after Perl's built-in grep() function.

    POE::Filter::Grep is designed to be combined with other filters through
    POE::Filter::Stackable. In the "SYNOPSIS" example, a filter stack is
    created to parse logs as lines and remove all entries that don't pertain
    to a sudo process. (Or if your glass is half full, the stack only
    selects entries that DO mention sudo.)

PUBLIC FILTER METHODS
    In addition to the usual POE::Filter methods, POE::Filter::Grep also
    supports the following.

  new
    new() constructs a new POE::Filter::Grep object. It must either be
    called with a single Code parameter, or both a Put and a Get parameter.
    The values for Code, Put, and Get are code references that, when
    invoked, return true to select an item or false to reject it. A Code
    function will be used for both input and output, while Get and Put
    functions allow input and output to be filtered in different ways. The
    item in question will be passed as the function's sole parameter.

      sub reject_bidoofs {
        my $pokemon = shift;
        return 1 if $pokemon ne "bidoof";
        return;
      }

      my $gotta_catch_nearly_all = POE::Filter::Grep->new(
        Code => \&reject_bidoofs,
      );

    Enforce read-only behavior:

      my $read_only = POE::Filter::Grep->new(
        Get => sub { 1 },
        Put => sub { 0 },
      );

  modify
    modify() changes a POE::Filter::Grep object's behavior at run-time. It
    accepts the same parameters as new(), and it replaces the existing tests
    with new ones.

      # Don't give away our Dialgas.
      $gotta_catch_nearly_all->modify(
        Get => sub { 1 },
        Put => sub { return shift() ne "dialga" },
      );

SEE ALSO
    POE::Filter for more information about filters in general.

    POE::Filter::Stackable for more details on stacking filters.

BUGS
    None known.

AUTHORS & COPYRIGHTS
    The Grep filter was contributed by Dieter Pearcey. Documentation is
    provided by Rocco Caputo.

    Please see the POE manpage for more information about authors and
    contributors.