1Mo::default(3)        User Contributed Perl Documentation       Mo::default(3)
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Name

6       Mo::default - Adds the default feature to Mo's has
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Synopsis

9           use Mo qw'default';
10           has job  => ( default => 'Killer' );
11           has name => ( default => sub { 'Joe' } );
12           has age      => 42;
13           has colors   => [ 'green', 'blue' ];
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Description

16       Adds the default parameter to has, which expects a value. If the value
17       is a code ref, it is called to produce the default. If the value is a
18       hash or array ref, then a shallow copy is made for the default. If
19       there is an odd number of arguments after the attribute name, then the
20       first value is the default.
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22       These 3 lines are the same:
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24           has things => default => sub {+{}};
25           has things => default => {};
26           has things => {};
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Laziness

29       Default attribute values in Mo are lazy by default.  This can be
30       changed by explicitly setting the "lazy" argument to false, in order to
31       cause it to be initialized during instantiation.
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33           use Mo qw'default';
34           has status   => 'active';                 # lazy
35           has location => sub { ... }, lazy => 1;   # lazy
36           has target   => sub { ... }, lazy => 0;   # eager
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38       To change the default behavior and make attributes to be initialized
39       eagerly by default, import "nonlazy".
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41           use Mo qw'default nonlazy';
42           has status   => 'active';                 # eager
43           has location => sub { ... }, lazy => 1;   # lazy
44           has target   => sub { ... }, lazy => 0;   # eager
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48perl v5.34.0                      2022-01-21                    Mo::default(3)