NAME

Moose::Cookbook::WTF - For when things go wrong with Moose

COMMON PROBLEMS

Speed

Why is my code taking so long to load?

Moose has a fairly heavy compile time burden, which it inherits from Class::MOP. If load/compile time is a concern for your application, Moose may not be the right tool for you.

Although, you should note that we are exploring the use of Module::Compile to try and reduce this problem, but nothing is ready yet.

Why are my objects taking so long to construct?

Moose uses a lot of introspection when constructing an instance, and introspection can be slow. However, this is a temporary problem, and is already solved in Class::MOP by making classes immutable. However immutable support in Moose is not ready yet, but will be soon.

Constructors

Accessors

I created an attribute, where are my accessors?

Accessors are not created implicitly, you must ask Moose to create them for you. My guess is that you have this:

  has 'foo' => (isa => 'Bar');

when what you really want to say is:

  has 'foo' => (isa => 'Bar', is => 'rw');

The reason this is so, is because it is a perfectly valid use case to not have an accessor. The simplest one is that you want to write your own. If Moose created on automatically, then because of the order in which classes are constructed, Moose would overwrite your custom accessor. You wouldn't want that would you?

Method Modfiers

How come I can't change @_ in a before modifier?

The before modifier simply is called before the main method. Its return values are simply ignored, and are not passed onto the main method body.

There are a number of reasons for this, but those arguments are too lengthy for this document. Instead, I suggest using an around modifier instead. Here is some sample code:

  around 'foo' => sub {
      my $next = shift;
      my ($self, @args) = @_;
      # do something silly here to @args 
      $next->($self, reverse(@args));  
  };

How come I can't see return values in an after modifier?

As with the before modifier, the after modifier is simply called after the main method. It is passed the original contents of @_ and not the return values of the main method.

Again, the arguments are too lengthy as to why this has to be. And as with before I recommend using an around modifier instead. Here is some sample code:

  around 'foo' => sub {
      my $next = shift;
      my ($self, @args) = @_;
      my @rv = $next->($self, @args);  
      # do something silly with the return values
      return reverse @rv;
  };

AUTHOR

Stevan Little <stevan@iinteractive.com>

COPYRIGHT AND LICENSE

Copyright 2006 by Infinity Interactive, Inc.

http://www.iinteractive.com

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

cpanm Moose

perl -MCPAN -e shell
install Moose