Aspect::Advice::After - Execute code after a function is called

  use Aspect;

  after {
      # Trace all returning calls to your module
      print STDERR "Called my function " . $_->sub_name . "\n";

      # Suppress exceptions AND alter the results to foo()
      if ( $_->short_name eq 'foo' ) {
          if ( $_->exception ) {
              $_->return_value(1);
          } else {
              $_->return_value( $_->return_value + 1 );
          }
      }

  } call qr/^ MyModule::\w+ $/

package Aspect::Advice::After;

use strict;
use warnings;

# Added by eilara as hack around caller() core dump
# NOTE: Now we've switched to Sub::Uplevel can this be removed? --ADAMK
use Carp::Heavy    (); 
use Carp           ();
use Sub::Uplevel   ();
use Aspect::Hook   ();
use Aspect::Advice ();
use Aspect::Point  ();

our $VERSION = '1.01';
our @ISA     = 'Aspect::Advice';

# NOTE: To simplify debugging of the generated code, all injected string
# fragments will be defined in $UPPERCASE, and all lexical variables to be
# accessed via the closure will be in $lowercase.
sub _install {
	my $self     = shift;
	my $pointcut = $self->pointcut;
	my $code     = $self->code;
	my $lexical  = $self->lexical;

	# Get the curried version of the pointcut we will use for the
	# runtime checks instead of the original.
	# Because $MATCH_RUN is used in boolean conditionals, if there
	# is nothing to do the compiler will optimise away the code entirely.
	my $curried   = $pointcut->curry_runtime;
	my $compiled  = $curried ? $curried->compiled_runtime : undef;
	my $MATCH_RUN = $compiled ? '$compiled->()' : 1;

	# When an aspect falls out of scope, we don't attempt to remove
	# the generated hook code, because it might (for reasons potentially
	# outside our control) have been recursively hooked several times
	# by both Aspect and other modules.
	# Instead, we store an "out of scope" flag that is used to shortcut
	# past the hook as quickely as possible.
	# This flag is shared between all the generated hooks for each
	# installed Aspect.
	# If the advice is going to last lexical then we don't need to
	# check or use the $out_of_scope variable.
	my $out_of_scope   = undef;
	my $MATCH_DISABLED = $lexical ? '$out_of_scope' : '0';

	# Find all pointcuts that are statically matched
	# wrap the method with advice code and install the wrapper
	foreach my $name ( $pointcut->match_all ) {
		my $NAME = $name; # For completeness

		no strict 'refs';
		my $original = *$name{CODE};
		unless ( $original ) {
			Carp::croak("Can't wrap non-existent subroutine ", $name);
		}

		# Any way to set prototypes other than eval?
		my $PROTOTYPE = prototype($original);
		   $PROTOTYPE = defined($PROTOTYPE) ? "($PROTOTYPE)" : '';

		# Generate the new function
		no warnings 'redefine';
		eval <<"END_PERL"; die $@ if $@;
		package Aspect::Hook;

		*$NAME = sub $PROTOTYPE {
			# Is this a lexically scoped hook that has finished
			goto &\$original if $MATCH_DISABLED;

			my \$wantarray = wantarray;
			if ( \$wantarray ) {
				my \$return = eval { [
					Sub::Uplevel::uplevel(
						2, \$original, \@_,
					)
				] };

				local \$Aspect::POINT = bless {
					type         => 'after',
					pointcut     => \$pointcut,
					original     => \$original,
					sub_name     => \$name,
					wantarray    => \$wantarray,
					args         => \\\@_,
					return_value => \$return,
					exception    => \$\@,
				}, 'Aspect::Point';

				unless ( $MATCH_RUN ) {
					return \@\$return unless \$Aspect::POINT->{exception};
					die \$Aspect::POINT->{exception};
				}

				# Execute the advice code
				local \$_ = \$Aspect::POINT;
				&\$code(\$Aspect::POINT);

				# Throw the same (or modified) exception
				my \$exception = \$_->{exception};
				die \$exception if \$exception;

				# Get the (potentially) modified return value
				return \@{\$_->{return_value}};
			}

			if ( defined \$wantarray ) {
				my \$return = eval {
					Sub::Uplevel::uplevel(
						2, \$original, \@_,
					)
				};

				local \$Aspect::POINT = bless {
					type         => 'after',
					pointcut     => \$pointcut,
					original     => \$original,
					sub_name     => \$name,
					wantarray    => \$wantarray,
					args         => \\\@_,
					return_value => \$return,
					exception    => \$\@,
				}, 'Aspect::Point';

				unless ( $MATCH_RUN ) {
					return \$return unless \$Aspect::POINT->{exception};
					die \$Aspect::POINT->{exception};
				}

				# Execute the advice code
				local \$_ = \$Aspect::POINT;
				&\$code(\$Aspect::POINT);

				# Throw the same (or modified) exception
				my \$exception = \$_->{exception};
				die \$exception if \$exception;

				# Return the potentially-modified value
				return \$_->{return_value};

			}

			eval {
				Sub::Uplevel::uplevel(
					2, \$original, \@_,
				)
			};

			local \$Aspect::POINT = bless {
				type         => 'after',
				pointcut     => \$pointcut,
				original     => \$original,
				sub_name     => \$name,
				wantarray    => \$wantarray,
				args         => \\\@_,
				return_value => undef,
				exception    => \$\@,
			}, 'Aspect::Point';

			unless ( $MATCH_RUN ) {
				return unless \$Aspect::POINT->{exception};
				die \$Aspect::POINT->{exception};
			}

			# Execute the advice code
			local \$_ = \$Aspect::POINT;
			&\$code(\$Aspect::POINT);

			# Throw the same (or modified) exception
			my \$exception = \$_->{exception};
			die \$exception if \$exception;

			return;
		};
END_PERL
		$self->{installed}++;
	}

	# If this will run lexical we don't need a descoping hook
	return unless $lexical;

	# Return the lexical descoping hook.
	# This MUST be stored and run at DESTROY-time by the
	# parent object calling _install. This is less bullet-proof
	# than the DESTROY-time self-executing blessed coderef
	return sub { $out_of_scope = 1 };
}

1;

__END__