X-Git-Url: http://git.shadowcat.co.uk/gitweb/gitweb.cgi?a=blobdiff_plain;f=lib%2Fnamespace%2Fclean.pm;h=93ecb9f8671aed10bd25ed1531464043bc0506c3;hb=fcfe7810e5ba4f72dadf41d7d7cd92621bbcad4f;hp=206148c24f4952f8b200556794535aa03cedf219;hpb=40aef9d69ad5c2a21995d57d3d783d84aff0b59d;p=p5sagit%2Fnamespace-clean.git diff --git a/lib/namespace/clean.pm b/lib/namespace/clean.pm index 206148c..93ecb9f 100644 --- a/lib/namespace/clean.pm +++ b/lib/namespace/clean.pm @@ -2,24 +2,25 @@ package namespace::clean; =head1 NAME -namespace::clean - Keep imports out of your namespace +namespace::clean - Keep imports and functions out of your namespace =cut use warnings; use strict; -use vars qw( $VERSION ); -use Symbol qw( qualify_to_ref ); -use Filter::EOF; +use vars qw( $VERSION $STORAGE_VAR $SCOPE_HOOK_KEY $SCOPE_EXPLICIT ); +use Symbol qw( qualify_to_ref ); +use B::Hooks::EndOfScope; =head1 VERSION -0.01 +0.11 =cut -$VERSION = 0.01; +$VERSION = '0.11'; +$STORAGE_VAR = '__NAMESPACE_CLEAN_STORAGE'; =head1 SYNOPSIS @@ -27,65 +28,268 @@ $VERSION = 0.01; use warnings; use strict; - use Carp qw(croak); # will be removed + use Carp qw(croak); # 'croak' will be removed - sub bar { 23 } # will be removed + sub bar { 23 } # 'bar' will be removed + # remove all previously defined functions use namespace::clean; - sub baz { bar() } # still defined, 'bar' still bound + sub baz { bar() } # 'baz' still defined, 'bar' still bound - ### Will print: - # No - # No - # Yes + # begin to collection function names from here again + no namespace::clean; + + sub quux { baz() } # 'quux' will be removed + + # remove all functions defined after the 'no' unimport + use namespace::clean; + + # Will print: 'No', 'No', 'Yes' and 'No' print +(__PACKAGE__->can('croak') ? 'Yes' : 'No'), "\n"; print +(__PACKAGE__->can('bar') ? 'Yes' : 'No'), "\n"; print +(__PACKAGE__->can('baz') ? 'Yes' : 'No'), "\n"; + print +(__PACKAGE__->can('quux') ? 'Yes' : 'No'), "\n"; 1; =head1 DESCRIPTION +=head2 Keeping packages clean + When you define a function, or import one, into a Perl package, it will naturally also be available as a method. This does not per se cause problems, but it can complicate subclassing and, for example, plugin -classes that are included by loading them as base classes. +classes that are included via multiple inheritance by loading them as +base classes. The C pragma will remove all previously declared or imported symbols at the end of the current package's compile cycle. -This means that functions are already bound by their name, and calls to -them still work. But they will not be available as methods on your class -or instances. +Functions called in the package itself will still be bound by their +name, but they won't show up as methods on your class or instances. + +By unimporting via C you can tell C to start +collecting functions for the next C specification. + +You can use the C<-except> flag to tell C that you +don't want it to remove a certain function or method. A common use would +be a module exporting an C method along with some functions: + + use ModuleExportingImport; + use namespace::clean -except => [qw( import )]; + +If you just want to C<-except> a single sub, you can pass it directly. +For more than one value you have to use an array reference. + +=head2 Explicitely removing functions when your scope is compiled + +It is also possible to explicitely tell C what packages +to remove when the surrounding scope has finished compiling. Here is an +example: + + package Foo; + use strict; + + # blessed NOT available + + sub my_class { + use Scalar::Util qw( blessed ); + use namespace::clean qw( blessed ); + + # blessed available + return blessed shift; + } + + # blessed NOT available + +=head2 Moose + +When using C together with L you want to keep +the installed C method. So your classes should look like: + + package Foo; + use Moose; + use namespace::clean -except => 'meta'; + ... + +Same goes for L. + +=head2 Cleaning other packages + +You can tell C that you want to clean up another package +instead of the one importing. To do this you have to pass in the C<-cleanee> +option like this: + + package My::MooseX::namespace::clean; + use strict; + + use namespace::clean (); # no cleanup, just load + + sub import { + namespace::clean->import( + -cleanee => scalar(caller), + -except => 'meta', + ); + } + +If you don't care about Cs discover-and-C<-except> logic, and +just want to remove subroutines, try L. =head1 METHODS You shouldn't need to call any of these. Just C the package at the appropriate place. +=cut + +=head2 clean_subroutines + +This exposes the actual subroutine-removal logic. + + namespace::clean->clean_subroutines($cleanee, qw( subA subB )); + +will remove C and C from C<$cleanee>. Note that this will remove the +subroutines B and not wait for scope end. If you want to have this +effect at a specific time (e.g. C acts on scope compile end) +it is your responsibility to make sure it runs at that time. + +=cut + +my $RemoveSubs = sub { + + my $cleanee = shift; + my $store = shift; + SYMBOL: + for my $f (@_) { + + # ignore already removed symbols + next SYMBOL if $store->{exclude}{ $f }; + no strict 'refs'; + + # keep original value to restore non-code slots + { no warnings 'uninitialized'; # fix possible unimports + local *__tmp = *{ ${ "${cleanee}::" }{ $f } }; + delete ${ "${cleanee}::" }{ $f }; + } + + SLOT: + # restore non-code slots to symbol + for my $t (qw( SCALAR ARRAY HASH IO FORMAT )) { + next SLOT unless defined *__tmp{ $t }; + *{ "${cleanee}::$f" } = *__tmp{ $t }; + } + } +}; + +sub clean_subroutines { + my ($nc, $cleanee, @subs) = @_; + $RemoveSubs->($cleanee, {}, @subs); +} + =head2 import -Makes a snapshot of the current defined functions and registers a -L cleanup routine to remove those symbols from the package -at the end of the compile-time. +Makes a snapshot of the current defined functions and installs a +L hook in the current scope to invoke the cleanups. =cut sub import { - my ($pragma) = @_; + my ($pragma, @args) = @_; - my $cleanee = caller; - my $functions = $pragma->get_functions($cleanee); - - Filter::EOF->on_eof_call(sub { + my (%args, $is_explicit); + + ARG: + while (@args) { + + if ($args[0] =~ /^\-/) { + my $key = shift @args; + my $value = shift @args; + $args{ $key } = $value; + } + else { + $is_explicit++; + last ARG; + } + } + + my $cleanee = exists $args{ -cleanee } ? $args{ -cleanee } : scalar caller; + if ($is_explicit) { + on_scope_end { + $RemoveSubs->($cleanee, {}, @args); + }; + } + else { + + # calling class, all current functions and our storage + my $functions = $pragma->get_functions($cleanee); + my $store = $pragma->get_class_store($cleanee); + + # except parameter can be array ref or single value + my %except = map {( $_ => 1 )} ( + $args{ -except } + ? ( ref $args{ -except } eq 'ARRAY' ? @{ $args{ -except } } : $args{ -except } ) + : () + ); + + # register symbols for removal, if they have a CODE entry for my $f (keys %$functions) { - next unless $functions->{ $f } + next if $except{ $f }; + next unless $functions->{ $f } and *{ $functions->{ $f } }{CODE}; - { no strict 'refs'; - delete ${ "${cleanee}::" }{ $f }; - } + $store->{remove}{ $f } = 1; } - }); + + # register EOF handler on first call to import + unless ($store->{handler_is_installed}) { + on_scope_end { + $RemoveSubs->($cleanee, $store, keys %{ $store->{remove} }); + }; + $store->{handler_is_installed} = 1; + } + + return 1; + } +} + +=head2 unimport + +This method will be called when you do a + + no namespace::clean; + +It will start a new section of code that defines functions to clean up. + +=cut + +sub unimport { + my ($pragma, %args) = @_; + + # the calling class, the current functions and our storage + my $cleanee = exists $args{ -cleanee } ? $args{ -cleanee } : scalar caller; + my $functions = $pragma->get_functions($cleanee); + my $store = $pragma->get_class_store($cleanee); + + # register all unknown previous functions as excluded + for my $f (keys %$functions) { + next if $store->{remove}{ $f } + or $store->{exclude}{ $f }; + $store->{exclude}{ $f } = 1; + } + + return 1; +} + +=head2 get_class_store + +This returns a reference to a hash in a passed package containing +information about function names included and excluded from removal. + +=cut + +sub get_class_store { + my ($pragma, $class) = @_; + no strict 'refs'; + return \%{ "${class}::${STORAGE_VAR}" }; } =head2 get_functions @@ -100,17 +304,34 @@ sub get_functions { my ($pragma, $class) = @_; return { - map { @$_ } - grep { *{ $_->[1] }{CODE} } - map { [$_, qualify_to_ref( $_, $class )] } - grep { $_ !~ /::$/ } - do { no strict 'refs'; keys %{ "${class}::" } } + map { @$_ } # key => value + grep { *{ $_->[1] }{CODE} } # only functions + map { [$_, qualify_to_ref( $_, $class )] } # get globref + grep { $_ !~ /::$/ } # no packages + do { no strict 'refs'; keys %{ "${class}::" } } # symbol entries }; } +=head1 IMPLEMENTATION DETAILS + +This module works through the effect that a + + delete $SomePackage::{foo}; + +will remove the C symbol from C<$SomePackage> for run time lookups +(e.g., method calls) but will leave the entry alive to be called by +already resolved names in the package itself. C will +restore and therefor in effect keep all glob slots that aren't C. + +A test file has been added to the perl core to ensure that this behaviour +will be stable in future releases. + +Just for completeness sake, if you want to remove the symbol completely, +use C instead. + =head1 SEE ALSO -L +L =head1 AUTHOR AND COPYRIGHT @@ -124,4 +345,5 @@ it under the same terms as perl itself. =cut -1; +no warnings; +'Danger! Laws of Thermodynamics may not apply.'