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.