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1 | |
2 | =pod |
3 | |
4 | =head1 NAME |
5 | |
6 | Moose::Cookbook::WTF - For when things go wrong with Moose |
7 | |
8 | =head1 COMMON PROBLEMS |
9 | |
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10 | =head2 Speed |
11 | |
12 | =head3 Why is my code taking so long to load? |
13 | |
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14 | Moose does have a compile time performance burden, |
15 | which it inherits from Class::MOP. If load/compile |
16 | time is a concern for your application, Moose may not |
17 | be the right tool for you. |
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18 | |
19 | Although, you should note that we are exploring the |
20 | use of L<Module::Compile> to try and reduce this problem, |
21 | but nothing is ready yet. |
22 | |
23 | =head3 Why are my objects taking so long to construct? |
24 | |
25 | Moose uses a lot of introspection when constructing an |
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26 | instance, and introspection can be slow. This problem |
27 | can be solved by making your class immutable. This can |
28 | be done with the following code: |
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29 | |
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30 | MyClass->meta->make_immutable(); |
31 | |
32 | Moose will then memoize a number of meta-level methods |
33 | and inline a constructor for you. For more information |
34 | on this see the L<Constructors> section below and in the |
35 | L<Moose::Cookbook::FAQ>. |
36 | |
37 | =head2 Constructors & Immutability |
38 | |
39 | =head3 I made my class immutable, but C<new> it is still slow! |
40 | |
41 | Do you have a custom C<new> method in your class? Moose |
42 | will not overwrite your custom C<new> method, you would |
43 | probably do better to try and convert this to use the |
44 | C<BUILD> method or possibly set C<default> values in |
45 | the attribute declaration. |
46 | |
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47 | =head3 I made my class immutable, and now my (before | after | |
48 | around) C<new> is not being called? |
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49 | |
50 | Making a I<before>, I<after> or I<around> wrap around the |
51 | C<new> method, will actually create a C<new> method within |
52 | your class. This will prevent Moose from creating one itself |
53 | when you make the class immutable. |
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54 | |
55 | =head2 Accessors |
56 | |
57 | =head3 I created an attribute, where are my accessors? |
58 | |
59 | Accessors are B<not> created implicitly, you B<must> ask Moose |
60 | to create them for you. My guess is that you have this: |
61 | |
62 | has 'foo' => (isa => 'Bar'); |
63 | |
64 | when what you really want to say is: |
65 | |
66 | has 'foo' => (isa => 'Bar', is => 'rw'); |
67 | |
68 | The reason this is so, is because it is a perfectly valid use |
69 | case to I<not> have an accessor. The simplest one is that you |
70 | want to write your own. If Moose created on automatically, then |
71 | because of the order in which classes are constructed, Moose |
72 | would overwrite your custom accessor. You wouldn't want that |
73 | would you? |
74 | |
75 | =head2 Method Modfiers |
76 | |
77 | =head3 How come I can't change C<@_> in a C<before> modifier? |
78 | |
79 | The C<before> modifier simply is called I<before> the main method. |
80 | Its return values are simply ignored, and are B<not> passed onto |
81 | the main method body. |
82 | |
83 | There are a number of reasons for this, but those arguments are |
84 | too lengthy for this document. Instead, I suggest using an C<around> |
85 | modifier instead. Here is some sample code: |
86 | |
87 | around 'foo' => sub { |
88 | my $next = shift; |
89 | my ($self, @args) = @_; |
90 | # do something silly here to @args |
91 | $next->($self, reverse(@args)); |
92 | }; |
93 | |
94 | =head3 How come I can't see return values in an C<after> modifier? |
95 | |
96 | As with the C<before> modifier, the C<after> modifier is simply |
97 | called I<after> the main method. It is passed the original contents |
98 | of C<@_> and B<not> the return values of the main method. |
99 | |
100 | Again, the arguments are too lengthy as to why this has to be. And |
101 | as with C<before> I recommend using an C<around> modifier instead. |
102 | Here is some sample code: |
103 | |
104 | around 'foo' => sub { |
105 | my $next = shift; |
106 | my ($self, @args) = @_; |
107 | my @rv = $next->($self, @args); |
108 | # do something silly with the return values |
109 | return reverse @rv; |
110 | }; |
111 | |
112 | =head1 AUTHOR |
113 | |
114 | Stevan Little E<lt>stevan@iinteractive.comE<gt> |
115 | |
116 | =head1 COPYRIGHT AND LICENSE |
117 | |
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118 | Copyright 2006, 2007 by Infinity Interactive, Inc. |
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119 | |
120 | L<http://www.iinteractive.com> |
121 | |
122 | This library is free software; you can redistribute it and/or modify |
123 | it under the same terms as Perl itself. |
124 | |
125 | =cut |