Devel::TraceMethods - Perl module for tracing module calls

Devel-TraceMethods documentation Contained in the Devel-TraceMethods distribution.

Index

Code Index:

NAME

Top

Devel::TraceMethods - Perl module for tracing module calls

SYNOPSIS

Top

  use Devel::TraceMethods qw( PackageOne PackageTwo );

DESCRIPTION

Top

Devel::TraceMethods allows you to attach a logging subroutine of your choosing to all of the methods and functions within multiple packages or classes. You can use this to trace execution. It even respects inheritance.

To enable logging, pass the name of the packages you wish to trace on the line where you use Devel::TraceMethods. It will automatically install logging for all functions in the named packages.

You can also call import() after you have use()d the module if you want to log functions and methods in another package.

You can specify per-package (or per-class) logging subroutines. For example:

  Devel::TraceMethods( SomePackage => \&log_one, OtherPackage => \&log_two );

callback( $subroutine_reference )

By default, Devel::TraceMethods uses Carp::carp() to log a method call. You can change this with the set_logger() function. Pass a subroutine reference as the only argument, and all subsequent calls to logged methods will use the new subroutine reference instead of carp().

The first argument to the logging subroutine is the full name of the logged method. The rest of the arguments are copies of those being passed to the logged method. You can modify them in the logging subroutine without disturbing your call.

TODO

Top

Unlog packages.
Attach to calling package if nothing is specified in @_? Something like:
	push @_, scalar caller() unless @_;
Attach only to specified methods.
Add ability to disable logging on certain methods.
Allow multiple logging subs.
Allow per-method logging sub?
Don't copy other slots of typeglob? (Could be tricky, an internals wizard will have to look at this.)

COPYRIGHT and AUTHOR

Top

Copyright (c) 2001, 2005 chromatic chromatic at wgz dot org.

Thanks to Tye McQueen for the initial suggestion, grinder at Perl Monks for the callback suggestion, and Podmaster for a suggestion on enhancing the default logging subroutine

SEE ALSO

Top

perl(1).

Devel-TraceMethods documentation Contained in the Devel-TraceMethods distribution. 
package Devel::TraceMethods;

use strict;

use vars '$VERSION';
$VERSION = '1.00';

sub import
{
	my $package = shift;

	while (@_)
	{
		my $traced = shift;
		my $logger = ref $_[0] eq 'CODE' && defined &{ $_[0] } ? shift : undef;
		_wrap_symbol( $traced, $logger );
	}
}

sub _wrap_symbol
{
	my ($traced, $logger) = @_;
	my $src;

	# get the calling package symbol table name
	{
		no strict 'refs';
		$src = \%{ $traced . '::' };
	}

	# loop through all symbols in calling package, looking for subs
	for my $symbol ( keys %$src )
	{
		# get all code references, make sure they're valid
		my $sub = *{ $src->{$symbol} }{CODE};
		next unless defined $sub and defined &$sub;

		# save all other slots of the typeglob
		my @slots;

		for my $slot (qw( SCALAR ARRAY HASH IO FORMAT ))
		{
			my $elem = *{ $src->{$symbol} }{$slot};
			next unless defined $elem;
			push @slots, $elem;
		}

		# clear out the source glob
		undef $src->{$symbol};

		# replace the sub in the source
		$src->{$symbol} = sub
		{
			my @args = @_;
			_log_call->( 
				name   => "${traced}::$symbol",
				logger => $logger,
				args   => [ @_ ]
			);
			return $sub->(@_);
		};

		# replace the other slot elements
		for my $elem (@slots)
		{
			$src->{$symbol} = $elem;
		}
	}
}

{
	my $logger = sub { require Carp; Carp::carp( join ', ', @_ ) };

	# set a callback sub for logging
	sub callback
	{
		# should allow this to be a class method :)
		shift if @_ > 1;

		my $coderef = shift;
		unless( ref($coderef) eq 'CODE' and defined(&$coderef) )
		{
			require Carp;
			Carp::croak( "$coderef is not a code reference!" );
		}

		$logger = $coderef;
	}

	# where logging actually happens
	sub _log_call
	{
		my %args    = @_;
		my $log_sub = $args{logger} || $logger;

		$log_sub->( $args{name}, @{ $args{args} });
	}
}

1;

__END__