package Devel::Events; # git description: v0.09-9-gb708a33
# vim: set ts=2 sw=2 noet nolist :
# ABSTRACT: Extensible instrumentation framework

use strict;
use warnings;

our $VERSION = '0.10';

__PACKAGE__;

__END__

=pod

=encoding UTF-8

=head1 NAME

Devel::Events - Extensible instrumentation framework

=head1 VERSION

version 0.10

=head1 SYNOPSIS

	use Devel::Events::Generator::Foo;
	use Devel::Events::Handler::Bar;
	use Devel::Events::Filter::Blort;

	my $h = Devel::Events::Generator->new(
		handler => Devel::Event::Filter->new(
			handler => Devel::Events::Handler::Bar->new(),
		),
	);

=head1 DESCRIPTION

L<Devel::Events> is an event generation, filtering and analaysis framework for
instrumenting and auditing perl code.

The design's purpose is to decouple the mechanics of code instrumentation from
the analysis, making it easier to write debugging/profiling tools.

L<Devel::Events::Generator> object fire events, which can be mangled by
L<Devel::Event::Filter> objects. Eventually any number of
L<Devel::Event::Handler> objects can receive a given event, and perform
analysis based on it.

For example L<Devel::Event::Handler::ObjectTracker> can be used to detect
leaks.

=head1 COMPONENT OVERVIEW

There are two main types of components - generators and handlers.

Filters are special types of handlers that always delegate to another handler.

The multiplex handler may be used to delegate to any number of handlers, and
can be the handler for several generators.

Using these basic components complex chains of handlers can be built to
properly analyze the events you are interested in.

=head2 Generators

=over 4

=item L<Devel::Events::Generator::Objects>

Generate C<object_bless> and C<object_destroy> events by overriding
C<CORE::GLOBAL::bless> and tracking every object using L<Variable::Magic>.

=item L<Devel::Events::Generator::SubTrace>

Uses the perl debugger hook to generate C<enter_sub> and C<leave_sub> events.

=item L<Devel::Events::Generator::LineTrace>

Fires an C<executing_line> event for every line using the perl debugger hook.

=item L<Devel::Events::Generator::Require>

Fires events for C<require> and c<use> calls.

=back

=head2 Handlers

=over 4

=item L<Devel::Events::Handler::Multiplex>

Repeat events to multiple handlers.

=item L<Devel::Events::Handler::Callback>

Make a handler object out of a callback.

=item L<Devel::Events::Handler::Log::Memory>

Log all events to an array.

Provides filtering and slicing methods to ease analysis.

=item L<Devel::Events::Handler::ObjectTracker>

Handles C<object_bless> and C<object_destroy> events (as generated by
L<Devel::Events::Generator::Objects>) to track the lifetime of objects. When
objects lifetimes extend beyond the scope they're supposed to be destroyed in
leaks can be detected.}

=back

=head2 Filters

=over 4

=item L<Devel::Events::Filter::Stamp>

Add various stamp data (time, process ID, thread ID if threads are loaded) to
events.

=item L<Devel::Events::Filter::Stringify>

Stringify (by default using L<overload/StrVal>, to avoid side effects) all
event data to avoid leaking.

=item L<Devel::Events::Filter::Size>

Add size reports to events using L<Devel::Size>

=item L<Devel::Events::Filter::RemoveFields>

Remove certain fields from events.

=item L<Devel::Events::Filter::Warn>

Runs C<warn "@event"> before delegating to the sub handler. Useful for
debugging handler chains.

=back

=head1 EVENT STRUCTURE

All events are passed as lists.

The default components will generate lists containing a single string which is
the event name, and then a list of key/value pairs.

=head1 SUPPORT

Bugs may be submitted through L<the RT bug tracker|https://rt.cpan.org/Public/Dist/Display.html?Name=Devel-Events>
(or L<bug-Devel-Events@rt.cpan.org|mailto:bug-Devel-Events@rt.cpan.org>).

=head1 AUTHOR

יובל קוג'מן (Yuval Kogman) <nothingmuch@woobling.org>

=head1 CONTRIBUTOR

=for stopwords Karen Etheridge

Karen Etheridge <ether@cpan.org>

=head1 COPYRIGHT AND LICENCE

This software is copyright (c) 2007 by יובל קוג'מן (Yuval Kogman).

This is free software; you can redistribute it and/or modify it under
the same terms as the Perl 5 programming language system itself.

=cut
