NAME

Type::Tiny::Intersection - intersection type constraints

SYNOPSIS

Using via the "&" operator overload:

  package Local::Stash {
    use Moo;
    use Types::Common qw( LowerCaseStr StrLength );
    
    has identifier => (
      is   => 'ro',
      isa  => (LowerCaseStr) & (StrLength[4, 8]),
    );
  }
  
  my $x = Local::Stash->new( data => {} );  # not ok
  my $y = Local::Stash->new( data => [] );  # not ok

Note that it is a good idea to enclose each type being intersected in parentheses to avoid Perl thinking the "&" is the sigil for a coderef.

Using Type::Tiny::Intersection's object-oriented interface:

  package Local::Stash {
    use Moo;
    use Types::Common qw( LowerCaseStr StrLength );
    use Type::Tiny::Intersection;
    
    my $ShortLcStr = Type::Tiny::Intersection->new(
      name             => 'AnyData',
      type_constraints => [ LowerCaseStr, StrLength[4, 8] ],
    );
    
    has identifier => (
      is   => 'ro',
      isa  => $ShortLcStr,
    );
  }

Using Type::Utils's functional interface:

  package Local::Stash {
    use Moo;
    use Types::Common qw( LowerCaseStr StrLength );
    use Type::Utils;
    
    my $ShortLcStr = intersection ShortLcStr => [ LowerCaseStr, StrLength[4, 8] ];
    
    has identifier => (
      is   => 'ro',
      isa  => $ShortLcStr,
    );
  }

STATUS

This module is covered by the Type-Tiny stability policy.

DESCRIPTION

Intersection type constraints.

Intersection type constraints are not often very useful. Consider the intersection of HashRef and ArrayRef. A value will only pass if it is both a hashref and an arrayref. Given that neither of those type constraints accept "undef" or overloaded objects, there is no possible value that can pass both.

Which is not to say that intersections are never useful, but it happens quite rarely.

This package inherits from Type::Tiny; see that for most documentation. Major differences are listed below:

Constructor

The "new" constructor from Type::Tiny still works, of course. But there is also:

new_by_overload(%attributes): Like the "new" constructor, but will sometimes return another type constraint which is not strictly an instance of Type::Tiny::Intersection, but still encapsulates the same meaning. This constructor is used by Type::Tiny's overloading of the "&" operator.

Attributes

"type_constraints": Arrayref of type constraints.
When passed to the constructor, if any of the type constraints in the intersection is itself an intersection type constraint, this is "exploded" into the new intersection.
"constraint": Unlike Type::Tiny, you cannot pass a constraint coderef to the constructor. Instead rely on the default.
"inlined": Unlike Type::Tiny, you cannot pass an inlining coderef to the constructor. Instead rely on the default.
"parent": Unlike Type::Tiny, you cannot pass an inlining coderef to the constructor. A parent will instead be automatically calculated.
(Technically any of the types in the intersection could be treated as a parent type; we choose the first arbitrarily.)

Methods

stringifies_to($constraint): See Type::Tiny::ConstrainedObject.
numifies_to($constraint): See Type::Tiny::ConstrainedObject.
"with_attribute_values($attr1 => $constraint1, ...)": See Type::Tiny::ConstrainedObject.

Overloading

•: Arrayrefification calls "type_constraints".

BUGS

Please report any bugs to <https://github.com/tobyink/p5-type-tiny/issues>.

AUTHOR

Toby Inkster <tobyink@cpan.org>.

COPYRIGHT AND LICENCE

This is free software; you can redistribute it and/or modify it under the same terms as the Perl 5 programming language system itself.

DISCLAIMER OF WARRANTIES

THIS PACKAGE IS PROVIDED "AS IS" AND WITHOUT ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.