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.IX Title "Declare::Constraints::Simple::Library::Referencial 3pm"
.TH Declare::Constraints::Simple::Library::Referencial 3pm "2018-03-31" "perl v5.26.1" "User Contributed Perl Documentation"
.\" For nroff, turn off justification.  Always turn off hyphenation; it makes
.\" way too many mistakes in technical documents.
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.nh
.SH "NAME"
Declare::Constraints::Simple::Library::Referencial \- Ref Constraints
.SH "SYNOPSIS"
.IX Header "SYNOPSIS"
.Vb 2
\&  # scalar or array references
\&  my $scalar_or_array = IsRefType( qw(SCALAR ARRAY) );
\&
\&  # scalar reference
\&  my $int_ref = IsScalarRef( IsInt );
\&
\&  # accept mappings of ids to objects with "name" methods
\&  my $id_obj_map = 
\&    IsHashRef( \-keys   => IsInt,
\&               \-values => And( IsObject,
\&                               HasMethods(\*(Aqname\*(Aq) ));
\&
\&  # an integer list
\&  my $int_list = IsArrayRef( IsInt );
\&
\&  # accept code references
\&  my $is_closure = IsCodeRef;
\&
\&  # accept a regular expression
\&  my $is_regex = IsRegex;
.Ve
.SH "DESCRIPTION"
.IX Header "DESCRIPTION"
This library contains those constraints that can test the validity of
references and their types.
.SH "CONSTRAINTS"
.IX Header "CONSTRAINTS"
.SS "IsRefType(@types)"
.IX Subsection "IsRefType(@types)"
Valid if the value is a reference of a kind in \f(CW@types\fR.
.SS "IsScalarRef($constraint)"
.IX Subsection "IsScalarRef($constraint)"
This is true if the value is a scalar reference. A possible constraint
for the scalar references target value can be passed. E.g.
.PP
.Vb 1
\&  my $test_integer_ref = IsScalarRef(IsInt);
.Ve
.SS "IsArrayRef($constraint)"
.IX Subsection "IsArrayRef($constraint)"
The value is valid if the value is an array reference. The contents of
the array can be validated by passing another \f(CW$constraint\fR as
argument.
.PP
The stack or path part of \f(CW\*(C`IsArrayRef\*(C'\fR is \f(CW\*(C`IsArrayRef[$index]\*(C'\fR where
\&\f(CW$index\fR is the index of the failing element.
.ie n .SS "IsHashRef(\-keys => $constraint, \-values => $constraint)"
.el .SS "IsHashRef(\-keys => \f(CW$constraint\fP, \-values => \f(CW$constraint\fP)"
.IX Subsection "IsHashRef(-keys => $constraint, -values => $constraint)"
True if the value is a hash reference. It can also take two named
parameters: \f(CW\*(C`\-keys\*(C'\fR can pass a constraint to check the hashes keys,
\&\f(CW\*(C`\-values\*(C'\fR does the same for its values.
.PP
The stack or path part of \f(CW\*(C`IsHashRef\*(C'\fR looks like 
\&\f(CW\*(C`IsHashRef[$type $key]\*(C'\fR where \f(CW$type\fR is either \f(CW\*(C`val\*(C'\fR or \f(CW\*(C`key\*(C'\fR 
depending on what was validated, and \f(CW$key\fR being the key that didn't 
pass validation.
.SS "\fIIsCodeRef()\fP"
.IX Subsection "IsCodeRef()"
Code references have to be valid to pass this constraint.
.SS "\fIIsRegex()\fP"
.IX Subsection "IsRegex()"
True if the value is a regular expression built with \f(CW\*(C`qr\*(C'\fR. \fBNote\fR
however, that a simple string that could be used like \f(CW\*(C`/$rx/\*(C'\fR will
not pass this constraint. You can combine multiple constraints with
And(@constraints) though.
.SH "SEE ALSO"
.IX Header "SEE ALSO"
Declare::Constraints::Simple, Declare::Constraints::Simple::Library
.SH "AUTHOR"
.IX Header "AUTHOR"
Robert 'phaylon' Sedlacek \f(CW\*(C`<phaylon@dunkelheit.at>\*(C'\fR
.SH "LICENSE AND COPYRIGHT"
.IX Header "LICENSE AND COPYRIGHT"
This module is free software, you can redistribute it and/or modify it 
under the same terms as perl itself.