Provided by: libtype-tiny-perl_0.022-1_all 
NAME
Type::Utils - utility functions to make defining and using type constraints a little
easier
SYNOPSIS
package Types::Mine;
use Type::Library -base;
use Type::Utils -all;
BEGIN { extends "Types::Standard" };
declare "AllCaps",
as "Str",
where { uc($_) eq $_ },
inline_as { my $varname = $_[1]; "uc($varname) eq $varname" };
coerce "AllCaps",
from "Str", via { uc($_) };
DESCRIPTION
This module provides utility functions to make defining and using type constraints a
little easier.
Type declaration functions
Many of the following are similar to the similarly named functions described in
Moose::Util::TypeConstraints.
"declare $name, %options"
"declare %options"
Declare a named or anonymous type constraint. Use "as" and "where" to specify the
parent type (if any) and (possibly) refine its definition.
declare EvenInt, as Int, where { $_ % 2 == 0 };
my $EvenInt = declare as Int, where { $_ % 2 == 0 };
NOTE: If the caller package inherits from Type::Library then any non-anonymous types
declared in the package will be automatically installed into the library.
Hidden gem: if you're inheriting from a type constraint that includes some coercions,
you can include "coerce => 1" in the %options hash to inherit the coercions.
"subtype $name, %options"
"subtype %options"
Declare a named or anonymous type constraint which is descended from an existing type
constraint. Use "as" and "where" to specify the parent type and refine its definition.
Actually, you should use "declare" instead; this is just an alias.
This function is not exported by default.
"type $name, %options"
"type %options"
Declare a named or anonymous type constraint which is not descended from an existing
type constraint. Use "where" to provide a coderef that constrains values.
Actually, you should use "declare" instead; this is just an alias.
This function is not exported by default.
"as $parent"
Used with "declare" to specify a parent type constraint:
declare EvenInt, as Int, where { $_ % 2 == 0 };
"where { BLOCK }"
Used with "declare" to provide the constraint coderef:
declare EvenInt, as Int, where { $_ % 2 == 0 };
The coderef operates on $_, which is the value being tested.
"message { BLOCK }"
Generate a custom error message when a value fails validation.
declare EvenInt,
as Int,
where { $_ % 2 == 0 },
message {
Int->validate($_) or "$_ is not divisible by two";
};
Without a custom message, the messages generated by Type::Tiny are along the lines of
Value "33" did not pass type constraint "EvenInt", which is usually reasonable.
"inline_as { BLOCK }"
Generate a string of Perl code that can be used to inline the type check into other
functions. If your type check is being used within a Moose or Moo constructor or
accessor methods, or used by Type::Params, this can lead to significant performance
improvements.
declare EvenInt,
as Int,
where { $_ % 2 == 0 },
inline_as {
my ($constraint, $varname) = @_;
my $perlcode =
$constraint->parent->inline_check($varname)
. "&& ($varname % 2 == 0)";
return $perlcode;
};
warn EvenInt->inline_check('$xxx'); # demonstration
Experimental: your "inline_as" block can return a list, in which case these will be
smushed together with "&&". The first item on the list may be undef, in which case the
undef will be replaced by the inlined parent type constraint. (And will throw an
exception if there is no parent.)
declare EvenInt,
as Int,
where { $_ % 2 == 0 },
inline_as {
return (undef, "($_ % 2 == 0)");
};
Returning a list like this is considered experimental, is not tested very much, and I
offer no guarantees that it will necessarily work with Moose/Mouse/Moo.
"class_type $name, { class => $package, %options }"
"class_type { class => $package, %options }"
Shortcut for declaring a Type::Tiny::Class type constraint.
"role_type $name, { role => $package, %options }"
"role_type { role => $package, %options }"
Shortcut for declaring a Type::Tiny::Role type constraint.
"duck_type $name, \@methods"
"duck_type \@methods"
Shortcut for declaring a Type::Tiny::Duck type constraint.
"union $name, \@constraints"
"union \@constraints"
Shortcut for declaring a Type::Tiny::Union type constraint.
"enum $name, \@values"
"enum \@values"
Shortcut for declaring a Type::Tiny::Enum type constraint.
"intersection $name, \@constraints"
"intersection \@constraints"
Shortcut for declaring a Type::Tiny::Intersection type constraint.
Coercion declaration functions
Many of the following are similar to the similarly named functions described in
Moose::Util::TypeConstraints.
"coerce $target, @coercions"
Add coercions to the target type constraint. The list of coercions is a list of type
constraint, conversion code pairs. Conversion code can be either a string of Perl code
or a coderef; in either case the value to be converted is $_.
"from $source"
Sugar to specify a type constraint in a list of coercions:
coerce EvenInt, from Int, via { $_ * 2 }; # As a coderef...
coerce EvenInt, from Int, q { $_ * 2 }; # or as a string!
"via { BLOCK }"
Sugar to specify a coderef in a list of coercions.
"declare_coercion $name, \%opts, $type1, $code1, ..."
"declare_coercion \%opts, $type1, $code1, ..."
Declares a coercion that is not explicitly attached to any type in the library. For
example:
declare_coercion "ArrayRefFromAny", from "Any", via { [$_] };
This coercion will be exportable from the library as a Type::Coercion object, but the
ArrayRef type exported by the library won't automatically use it.
Coercions declared this way are immutable (frozen).
"to_type $type"
Used with "declare_coercion" to declare the target type constraint for a coercion, but
still without explicitly attaching the coercion to the type constraint:
declare_coercion "ArrayRefFromAny",
to_type "ArrayRef",
from "Any", via { [$_] };
You should pretty much always use this when declaring an unattached coercion because
it's exceedingly useful for a type coercion to know what it will coerce to - this
allows it to skip coercion when no coercion is needed (e.g. avoiding coercing "[]" to
"[ [] ]") and allows "assert_coerce" to work properly.
Type library management
"extends @libraries"
Indicates that this type library extends other type libraries, importing their type
constraints.
Should usually be executed in a "BEGIN" block.
This is not exported by default because it's not fun to export it to Moo, Moose or
Mouse classes! "use Type::Utils -all" can be used to import it into your type library.
Other
"match_on_type $value => ($type => \&action, ..., \&default?)"
Something like a "switch"/"case" or "given"/"when" construct. Dispatches along
different code paths depending on the type of the incoming value. Example blatantly
stolen from the Moose documentation:
sub to_json
{
my $value = shift;
return match_on_type $value => (
HashRef() => sub {
my $hash = shift;
'{ '
. (
join ", " =>
map { '"' . $_ . '" : ' . to_json( $hash->{$_} ) }
sort keys %$hash
) . ' }';
},
ArrayRef() => sub {
my $array = shift;
'[ '.( join ", " => map { to_json($_) } @$array ).' ]';
},
Num() => q {$_},
Str() => q { '"' . $_ . '"' },
Undef() => q {'null'},
=> sub { die "$_ is not acceptable json type" },
);
}
Note that unlike Moose, code can be specified as a string instead of a coderef. (e.g.
for "Num", "Str" and "Undef" above.)
For improved performance, try "compile_match_on_type".
This function is not exported by default.
"my $coderef = compile_match_on_type($type => \&action, ..., \&default?)"
Compile a "match_on_type" block into a coderef. The following JSON converter is about
two orders of magnitude faster than the previous example:
sub to_json;
*to_json = compile_match_on_type(
HashRef() => sub {
my $hash = shift;
'{ '
. (
join ", " =>
map { '"' . $_ . '" : ' . to_json( $hash->{$_} ) }
sort keys %$hash
) . ' }';
},
ArrayRef() => sub {
my $array = shift;
'[ '.( join ", " => map { to_json($_) } @$array ).' ]';
},
Num() => q {$_},
Str() => q { '"' . $_ . '"' },
Undef() => q {'null'},
=> sub { die "$_ is not acceptable json type" },
);
Remember to store the coderef somewhere fairly permanent so that you don't compile it
over and over. "state" variables (in Perl >= 5.10) are good for this. (Same sort of
idea as Type::Params.)
This function is not exported by default.
"dwim_type($string, %options)"
Given a string like "ArrayRef[Int|CodeRef]", turns it into a type constraint object,
hopefully doing what you mean.
It uses the syntax of Type::Parser. Firstly the Type::Registry for the caller package
is consulted; if that doesn't have a match, Types::Standard is consulted for type
constraint names; and if there's still no match, then if a type constraint looks like
a class name, a new Type::Tiny::Class object is created for it.
Somewhere along the way, it also checks Moose/Mouse's type constraint registries if
they are loaded.
You can specify an alternative for the caller using the "for" option. If you'd rather
create a Type::Tiny::Role object, set the "does" option to true.
# An arrayref of objects, each of which must do role Foo.
my $type = dwim_type("ArrayRef[Foo]", does => 1);
Type::Registry->for_me->add_types("-Standard");
Type::Registry->for_me->alias_type("Int" => "Foo");
# An arrayref of integers.
my $type = dwim_type("ArrayRef[Foo]", does => 1);
While it's probably better overall to use the proper Type::Registry interface for
resolving type constraint strings, this function often does what you want.
It should never die if it fails to find a type constraint (but may die if the type
constraint string is syntactically malformed), preferring to return undef.
This function is not exported by default.
EXPORT
By default, all of the functions documented above are exported, except "subtype" and
"type" (prefer "declare" instead), "extends", "dwim_type", and
"match_on_type"/"compile_match_on_type".
This module uses Exporter::TypeTiny; see the documentation of that module for tips and
tricks importing from Type::Utils.
BUGS
Please report any bugs to <http://rt.cpan.org/Dist/Display.html?Queue=Type-Tiny>.
SEE ALSO
Type::Tiny::Manual.
Type::Tiny, Type::Library, Types::Standard, Type::Coercion.
Type::Tiny::Class, Type::Tiny::Role, Type::Tiny::Duck, Type::Tiny::Enum,
Type::Tiny::Union.
Moose::Util::TypeConstraints, Mouse::Util::TypeConstraints.
AUTHOR
Toby Inkster <tobyink@cpan.org>.
COPYRIGHT AND LICENCE
This software is copyright (c) 2013 by Toby Inkster.
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.