Version 0.09.

[p5sagit/namespace-clean.git] / README

NAME
    namespace::clean - Keep imports and functions out of your namespace

VERSION
    0.08

SYNOPSIS
      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;

DESCRIPTION
  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 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.

  Explicitely removing functions when your scope is compiled
    It is also possible to explicitely 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

  Moose
    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 Moose::Role.

METHODS
    You shouldn't need to call any of these. Just "use" the package at the
    appropriate place.

  import
    Makes a snapshot of the current defined functions and installs a
    Scope::Guard in the current scope to invoke the cleanups.

  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.

  get_class_store
    This returns a reference to a hash in a passed package containing
    information about function names included and excluded from removal.

  get_functions
    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.

IMPLEMENTATION DETAILS
    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.

SEE ALSO
    Scope::Guard

AUTHOR AND COPYRIGHT
    Robert 'phaylon' Sedlacek "<rs@474.at>", with many thanks to Matt S
    Trout for the inspiration on the whole idea.

LICENSE
    This program is free software; you can redistribute it and/or modify it
    under the same terms as perl itself.