1MooseX::SetOnce(3) User Contributed Perl Documentation MooseX::SetOnce(3)
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6 MooseX::SetOnce - write-once, read-many attributes for Moose
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9 version 0.200002
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12 Add the "SetOnce" trait to attributes:
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14 package Class;
15 use Moose;
16 use MooseX::SetOnce;
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18 has some_attr => (
19 is => 'rw',
20 traits => [ qw(SetOnce) ],
21 );
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23 ...and then you can only set them once:
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25 my $object = Class->new;
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27 $object->some_attr(10); # works fine
28 $object->some_attr(20); # throws an exception: it's already set!
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31 The 'SetOnce' attribute lets your class have attributes that are not
32 lazy and not set, but that cannot be altered once set.
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34 The logic is very simple: if you try to alter the value of an
35 attribute with the SetOnce trait, either by accessor or writer, and the
36 attribute has a value, it will throw an exception.
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38 If the attribute has a clearer, you may clear the attribute and set it
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42 Ricardo SIGNES <rjbs@cpan.org>
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45 This software is copyright (c) 2013 by Ricardo SIGNES.
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47 This is free software; you can redistribute it and/or modify it under
48 the same terms as the Perl 5 programming language system itself.
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52perl v5.28.1 2013-10-05 MooseX::SetOnce(3)