1Declare::Constraints::SUismeprleCD:oe:ncLtlirabirrbeau:rt:yeC:do:nOPspeterrrlaaitDnootrcssu:(m:3eS)nitmaptlieo:n:Library::Operators(3)
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NAME

6       Declare::Constraints::Simple::Library::Operators - Operators
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SYNOPSIS

9         # all hast to be valid
10         my $and_constraint = And( IsInt,
11                                   Matches(qr/0$/) );
12
13         # at least one has to be valid
14         my $or_constraint = Or( IsInt, HasLength );
15
16         # only one can be valid
17         my $xor_constraint = XOr( IsClass, IsObject );
18
19         # reverse validity
20         my $not_an_integer = Not( IsInt );
21
22         # case valid, validate 'bar' key depending on 'foo' keys value
23         my $struct_prof =
24           And( IsHashRef,
25                CaseValid( OnHashKeys(foo => IsEq("FooArray")),
26                             OnHashKeys(bar => IsArrayRef),
27                           OnHashKeys(foo => IsEq("FooHash")),
28                             OnHashKeys(bar => IsHashRef) ));
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DESCRIPTION

31       This module contains the frameworks operators. These constraint like
32       elements act on the validity of passed constraints.
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OPERATORS

35       And(@constraints)
36
37       Is true if all passed @constraints are true on the value. Returns the
38       result of the first failing constraint.
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40       Or(@constraints)
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42       Is true if at least one of the passed @contraints is true. Returns the
43       last failing constraint's result if false.
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45       XOr(@constraints)
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47       Valid only if a single one of the passed @constraints is valid. Returns
48       the last failing constraint's result if false.
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50       Not($constraint)
51
52       This is valid if the passed $constraint is false. The main purpose of
53       this operator is to allow the easy reversion of a constraint's true‐
54       ness.
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56       CaseValid($test, $conseq, $test2, $conseq2, ...)
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58       This runs every given $test argument on the value, until it finds one
59       that returns true. If none is found, false is returned. On a true
60       result, howver, the corresponding $conseq constraint is applied to the
61       value and it's result returned. This allows validation depending on
62       other properties of the value:
63
64         my $flexible = CaseValid( IsArrayRef,
65                                     And( HasArraySize(1,5),
66                                          OnArrayElements(0 => IsInt) ),
67                                   IsHashRef,
68                                     And( HasHashElements(qw( head tail )),
69                                          OnHashKeys(head => IsInt) ));
70
71       Of course, you could model most of it probably with the other opera‐
72       tors, but this is a bit more readable. For default cases use "Return‐
73       True" from Declare::Constraints::Simple::Library::General as test.
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SEE ALSO

76       Declare::Constraints::Simple, Declare::Constraints::Simple::Library
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AUTHOR

79       Robert 'phaylon' Sedlacek "<phaylon@dunkelheit.at>"
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82       This module is free software, you can redistribute it and/or modify it
83       under the same terms as perl itself.
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87perl v5.8.8                Declare2:0:0C6o-n0s9t-r1a1ints::Simple::Library::Operators(3)
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