namespace::clean - Keep imports and functions out of your namespace
package Foo;
use warnings;
use strict;
use Carp qw(croak); # 'croak' will be removed
sub bar { 23 } # 'bar' will be removed
# remove all previously defined functions
use namespace::clean;
sub baz { bar() } # 'baz' still defined, 'bar' still bound
# 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;
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 via multiple inheritance by loading them as
base classes.
The namespace::clean pragma will remove all previously declared or
imported symbols at the end of the current package's compile cycle.
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 no you can tell namespace::clean to start
collecting functions for the next use namespace::clean; specification.
You can use the -except flag to tell namespace::clean that you
don't want it to remove a certain function or method. A common use would
be a module exporting an import method along with some functions:
use ModuleExportingImport;
use namespace::clean -except => [qw( import )];
If you just want to -except a single sub, you can pass it directly.
For more than one value you have to use an array reference.
Note that the technique used by this module relies
on perl having resolved all names to actual code references during the
compilation of a scope. While this is almost always what the interpreter does,
there are some exceptions, notably the sort SUBNAME style of
the sort built-in invocation. The following example will not work, because
sort does not try to resolve the function name to an actual code reference
until runtime.
use MyApp::Utils 'my_sorter';
use namespace::clean;
my @sorted = sort my_sorter @list;
You need to work around this by forcing a compile-time resolution like so:
use MyApp::Utils 'my_sorter';
use namespace::clean;
my $my_sorter_cref = \&my_sorter;
my @sorted = sort $my_sorter_cref @list;
It is also possible to explicitly tell namespace::clean what packages
to remove when the surrounding scope has finished compiling. Here is an
example:
package Foo;
use strict;
# blessed NOT available
sub my_class {
use Scalar::Util qw( blessed );
use namespace::clean qw( blessed );
# blessed available
return blessed shift;
}
# blessed NOT available
When using namespace::clean together with Moose you want to keep
the installed meta method. So your classes should look like:
package Foo;
use Moose;
use namespace::clean -except => 'meta';
...
Same goes for the Moose::Role manpage.
You can tell namespace::clean that you want to clean up another package
instead of the one importing. To do this you have to pass in the -cleanee
option like this:
package My::MooseX::namespace::clean;
use strict;
use namespace::clean (); # no cleanup, just load
sub import {
namespace::clean->import(
-cleanee => scalar(caller),
-except => 'meta',
);
}
If you don't care about namespace::clean s discover-and--except logic, and
just want to remove subroutines, try clean_subroutines.
This exposes the actual subroutine-removal logic.
namespace::clean->clean_subroutines($cleanee, qw( subA subB ));
will remove subA and subB from $cleanee . Note that this will remove the
subroutines immediately and not wait for scope end. If you want to have this
effect at a specific time (e.g. namespace::clean acts on scope compile end)
it is your responsibility to make sure it runs at that time.
Makes a snapshot of the current defined functions and installs a
the B::Hooks::EndOfScope manpage hook in the current scope to invoke the cleanups.
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.
This returns a reference to a hash in a passed package containing
information about function names included and excluded from removal.
Takes a class as argument and returns all currently defined functions
in it as a hash reference with the function name as key and a typeglob
reference to the symbol as value.
This module works through the effect that a
delete $SomePackage::{foo};
will remove the foo symbol from $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. namespace::clean will
restore and therefor in effect keep all glob slots that aren't CODE .
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 undef instead.
the B::Hooks::EndOfScope manpage
Many thanks to Matt S Trout for the inspiration on the whole idea.
This software is copyright (c) 2011 by AUTHORS
This is free software; you can redistribute it and/or modify it under the same terms as the Perl 5 programming language system itself.
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