Provided by: libtype-tiny-perl_1.002001-1_all bug

NAME

       Type::Tiny - tiny, yet Moo(se)-compatible type constraint

SYNOPSIS

          use Scalar::Util qw(looks_like_number);
          use Type::Tiny;

          my $NUM = "Type::Tiny"->new(
             name       => "Number",
             constraint => sub { looks_like_number($_) },
             message    => sub { "$_ ain't a number" },
          );

          package Ermintrude {
             use Moo;
             has favourite_number => (is => "ro", isa => $NUM);
          }

          package Bullwinkle {
             use Moose;
             has favourite_number => (is => "ro", isa => $NUM);
          }

          package Maisy {
             use Mouse;
             has favourite_number => (is => "ro", isa => $NUM);
          }

STATUS

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

DESCRIPTION

       Type::Tiny is a tiny class for creating Moose-like type constraint objects which are
       compatible with Moo, Moose and Mouse.

       Maybe now we won't need to have separate MooseX, MouseX and MooX versions of everything?
       We can but hope...

       This documents the internals of Type::Tiny. Type::Tiny::Manual is a better starting place
       if you're new.

   Constructor
       "new(%attributes)"
           Moose-style constructor function.

   Attributes
       Attributes are named values that may be passed to the constructor. For each attribute,
       there is a corresponding reader method. For example:

          my $type = Type::Tiny->new( name => "Foo" );
          print $type->name, "\n";   # says "Foo"

       Important attributes

       These are the attributes you are likely to be most interested in providing when creating
       your own type constraints, and most interested in reading when dealing with type
       constraint objects.

       "constraint"
           Coderef to validate a value ($_) against the type constraint.  The coderef will not be
           called unless the value is known to pass any parent type constraint (see "parent"
           below).

           Alternatively, a string of Perl code checking $_ can be passed as a parameter to the
           constructor, and will be converted to a coderef.

           Defaults to "sub { 1 }" - i.e. a coderef that passes all values.

       "parent"
           Optional attribute; parent type constraint. For example, an "Integer" type constraint
           might have a parent "Number".

           If provided, must be a Type::Tiny object.

       "inlined"
           A coderef which returns a string of Perl code suitable for inlining this type.
           Optional.

           If "constraint" (above) is a coderef generated via Sub::Quote, then Type::Tiny may be
           able to automatically generate "inlined" for you.  If "constraint" (above) is a
           string, it will be able to.

       "name"
           The name of the type constraint. These need to conform to certain naming rules (they
           must begin with an uppercase letter and continue using only letters, digits 0-9 and
           underscores).

           Optional; if not supplied will be an anonymous type constraint.

       "display_name"
           A name to display for the type constraint when stringified. These don't have to
           conform to any naming rules. Optional; a default name will be calculated from the
           "name".

       "library"
           The package name of the type library this type is associated with.  Optional.
           Informational only: setting this attribute does not install the type into the package.

       "message"
           Coderef that returns an error message when $_ does not validate against the type
           constraint. Optional (there's a vaguely sensible default.)

       "coercion"
           A Type::Coercion object associated with this type.

           Generally speaking this attribute should not be passed to the constructor; you should
           rely on the default lazily-built coercion object.

           You may pass "coercion => 1" to the constructor to inherit coercions from the
           constraint's parent. (This requires the parent constraint to have a coercion.)

       "my_methods"
           Experimenal hashref of additional methods that can be called on the type constraint
           object.

       Attributes related to parameterizable and parameterized types

       The following additional attributes are used for parameterizable (e.g.  "ArrayRef") and
       parameterized (e.g. "ArrayRef[Int]") type constraints. Unlike Moose, these aren't handled
       by separate subclasses.

       "constraint_generator"
           Coderef that generates a new constraint coderef based on parameters.  Alternatively,
           the constraint generator can return a fully-formed Type::Tiny object, in which case
           the "name_generator", "inline_generator", and "coercion_generator" attributes
           documented below are ignored.

           Optional; providing a generator makes this type into a parameterizable type
           constraint.

       "name_generator"
           A coderef which generates a new display_name based on parameters.  Optional; the
           default is reasonable.

       "inline_generator"
           A coderef which generates a new inlining coderef based on parameters.

       "coercion_generator"
           A coderef which generates a new Type::Coercion object based on parameters.

       "deep_explanation"
           This API is not finalized. Coderef used by Error::TypeTiny::Assertion to peek inside
           parameterized types and figure out why a value doesn't pass the constraint.

       "parameters"
           In parameterized types, returns an arrayref of the parameters.

       Lazy generated attributes

       The following attributes should not be usually passed to the constructor; unless you're
       doing something especially unusual, you should rely on the default lazily-built return
       values.

       "compiled_check"
           Coderef to validate a value ($_[0]) against the type constraint.  This coderef is
           expected to also handle all validation for the parent type constraints.

       "complementary_type"
           A complementary type for this type. For example, the complementary type for an integer
           type would be all things that are not integers, including floating point numbers, but
           also alphabetic strings, arrayrefs, filehandles, etc.

       "moose_type", "mouse_type"
           Objects equivalent to this type constraint, but as a Moose::Meta::TypeConstraint or
           Mouse::Meta::TypeConstraint.

           It should rarely be necessary to obtain a Moose::Meta::TypeConstraint object from
           Type::Tiny because the Type::Tiny object itself should be usable pretty much anywhere
           a Moose::Meta::TypeConstraint is expected.

   Methods
       Predicate methods

       These methods return booleans indicating information about the type constraint. They are
       each tightly associated with a particular attribute.  (See "Attributes".)

       "has_parent", "has_library", "has_inlined", "has_constraint_generator",
       "has_inline_generator", "has_coercion_generator", "has_parameters", "has_message",
       "has_deep_explanation"
           Simple Moose-style predicate methods indicating the presence or absence of an
           attribute.

       "has_coercion"
           Predicate method with a little extra DWIM. Returns false if the coercion is a no-op.

       "is_anon"
           Returns true iff the type constraint does not have a "name".

       "is_parameterized", "is_parameterizable"
           Indicates whether a type has been parameterized (e.g. "ArrayRef[Int]") or could
           potentially be (e.g. "ArrayRef").

       Validation and coercion

       The following methods are used for coercing and validating values against a type
       constraint:

       "check($value)"
           Returns true iff the value passes the type constraint.

       "validate($value)"
           Returns the error message for the value; returns an explicit undef if the value passes
           the type constraint.

       "assert_valid($value)"
           Like "check($value)" but dies if the value does not pass the type constraint.

           Yes, that's three very similar methods. Blame Moose::Meta::TypeConstraint whose API
           I'm attempting to emulate. :-)

       "assert_return($value)"
           Like "assert_valid($value)" but returns the value if it passes the type constraint.

           This seems a more useful behaviour than "assert_valid($value)". I would have just
           changed "assert_valid($value)" to do this, except that there are edge cases where it
           could break Moose compatibility.

       "get_message($value)"
           Returns the error message for the value; even if the value passes the type constraint.

       "validate_explain($value, $varname)"
           Like "validate" but instead of a string error message, returns an arrayref of strings
           explaining the reasoning why the value does not meet the type constraint, examining
           parent types, etc.

           The $varname is an optional string like '$foo' indicating the name of the variable
           being checked.

       "coerce($value)"
           Attempt to coerce $value to this type.

       "assert_coerce($value)"
           Attempt to coerce $value to this type. Throws an exception if this is not possible.

       Child type constraint creation and parameterization

       These methods generate new type constraint objects that inherit from the constraint they
       are called upon:

       "create_child_type(%attributes)"
           Construct a new Type::Tiny object with this object as its parent.

       "where($coderef)"
           Shortcut for creating an anonymous child type constraint. Use it like
           "HashRef->where(sub { exists($_->{name}) })". That said, you can get a similar result
           using overloaded "&":

              HashRef & sub { exists($_->{name}) }

           Like the "constraint" attribute, this will accept a string of Perl code:

              HashRef->where('exists($_->{name})')

       "child_type_class"
           The class that create_child_type will construct by default.

       "parameterize(@parameters)"
           Creates a new parameterized type; throws an exception if called on a non-
           parameterizable type.

       "of(@parameters)"
           A cute alias for "parameterize". Use it like "ArrayRef->of(Int)".

       "plus_coercions($type1, $code1, ...)"
           Shorthand for creating a new child type constraint with the same coercions as this
           one, but then adding some extra coercions (at a higher priority than the existing
           ones).

       "plus_fallback_coercions($type1, $code1, ...)"
           Like "plus_coercions", but added at a lower priority.

       "minus_coercions($type1, ...)"
           Shorthand for creating a new child type constraint with fewer type coercions.

       "no_coercions"
           Shorthand for creating a new child type constraint with no coercions at all.

       Type relationship introspection methods

       These methods allow you to determine a type constraint's relationship to other type
       constraints in an organised hierarchy:

       "equals($other)", "is_subtype_of($other)", "is_supertype_of($other)",
       "is_a_type_of($other)"
           Compare two types. See Moose::Meta::TypeConstraint for what these all mean.  (OK,
           Moose doesn't define "is_supertype_of", but you get the idea, right?)

           Note that these have a slightly DWIM side to them. If you create two Type::Tiny::Class
           objects which test the same class, they're considered equal. And:

              my $subtype_of_Num = Types::Standard::Num->create_child_type;
              my $subtype_of_Int = Types::Standard::Int->create_child_type;
              $subtype_of_Int->is_subtype_of( $subtype_of_Num );  # true

       "strictly_equals($other)", "is_strictly_subtype_of($other)",
       "is_strictly_supertype_of($other)", "is_strictly_a_type_of($other)"
           Stricter versions of the type comparison functions. These only care about explicit
           inheritance via "parent".

              my $subtype_of_Num = Types::Standard::Num->create_child_type;
              my $subtype_of_Int = Types::Standard::Int->create_child_type;
              $subtype_of_Int->is_strictly_subtype_of( $subtype_of_Num );  # false

       "parents"
           Returns a list of all this type constraint's ancestor constraints. For example, if
           called on the "Str" type constraint would return the list "(Value, Defined, Item,
           Any)".

           Due to a historical misunderstanding, this differs from the Moose implementation of
           the "parents" method. In Moose, "parents" only returns the immediate parent type
           constraints, and because type constraints only have one immediate parent, this is
           effectively an alias for "parent". The extension module
           MooseX::Meta::TypeConstraint::Intersection is the only place where multiple type
           constraints are returned; and they are returned as an arrayref in violation of the
           base class' documentation. I'm keeping my behaviour as it seems more useful.

       "find_parent($coderef)"
           Loops through the parent type constraints including the invocant itself and returns
           the nearest ancestor type constraint where the coderef evaluates to true. Within the
           coderef the ancestor currently being checked is $_. Returns undef if there is no
           match.

           In list context also returns the number of type constraints which had been looped
           through before the matching constraint was found.

       "coercibles"
           Return a type constraint which is the union of type constraints that can be coerced to
           this one (including this one). If this type constraint has no coercions, returns
           itself.

       "type_parameter"
           In parameterized type constraints, returns the first item on the list of parameters;
           otherwise returns undef. For example:

              ( ArrayRef[Int] )->type_parameter;    # returns Int
              ( ArrayRef[Int] )->parent;            # returns ArrayRef

           Note that parameterizable type constraints can perfectly legitimately take multiple
           parameters (several off the parameterizable type constraints in Types::Standard do).
           This method only returns the first such parameter.  "Attributes related to
           parameterizable and parameterized types" documents the "parameters" attribute, which
           returns an arrayref of all the parameters.

       Inlining methods

       The following methods are used to generate strings of Perl code which may be pasted into
       stringy "eval"uated subs to perform type checks:

       "can_be_inlined"
           Returns boolean indicating if this type can be inlined.

       "inline_check($varname)"
           Creates a type constraint check for a particular variable as a string of Perl code.
           For example:

              print( Types::Standard::Num->inline_check('$foo') );

           prints the following output:

              (!ref($foo) && Scalar::Util::looks_like_number($foo))

           For Moose-compat, there is an alias "_inline_check" for this method.

       "inline_assert($varname)"
           Much like "inline_check" but outputs a statement of the form:

              die ... unless ...;

           Note that if this type has a custom error message, the inlined code will ignore this
           custom message!!

       Other methods

       "qualified_name"
           For non-anonymous type constraints that have a library, returns a qualified
           "MyLib::MyType" sort of name. Otherwise, returns the same as "name".

       "isa($class)", "can($method)", "AUTOLOAD(@args)"
           If Moose is loaded, then the combination of these methods is used to mock a
           Moose::Meta::TypeConstraint.

           If Mouse is loaded, then "isa" mocks Mouse::Meta::TypeConstraint.

       "DOES($role)"
           Overridden to advertise support for various roles.

           See also Type::API::Constraint, etc.

       "TIESCALAR", "TIEARRAY", "TIEHASH"
           These are provided as hooks that wrap Type::Tie. (Type::Tie is distributed separately,
           and can be used with non-Type::Tiny type constraints too.) They allow the following to
           work:

              use Types::Standard qw(Int);
              tie my @list, Int;
              push @list, 123, 456;   # ok
              push @list, "Hello";    # dies

       The following methods exist for Moose/Mouse compatibility, but do not do anything useful.

       "compile_type_constraint"
       "hand_optimized_type_constraint"
       "has_hand_optimized_type_constraint"
       "inline_environment"
       "meta"

   Overloading
       •   Stringification is overloaded to return the qualified name.

       •   Boolification is overloaded to always return true.

       •   Coderefification is overloaded to call "assert_return".

       •   On Perl 5.10.1 and above, smart match is overloaded to call "check".

       •   The "==" operator is overloaded to call "equals".

       •   The "<" and ">" operators are overloaded to call "is_subtype_of" and
           "is_supertype_of".

       •   The "~" operator is overloaded to call "complementary_type".

       •   The "|" operator is overloaded to build a union of two type constraints.  See
           Type::Tiny::Union.

       •   The "&" operator is overloaded to build the intersection of two type constraints. See
           Type::Tiny::Intersection.

       Previous versions of Type::Tiny would overload the "+" operator to call "plus_coercions"
       or "plus_fallback_coercions" as appropriate.  Support for this was dropped after 0.040.

   Constants
       "Type::Tiny::SUPPORT_SMARTMATCH"
           Indicates whether the smart match overload is supported on your version of Perl.

   Package Variables
       $Type::Tiny::DD
           This undef by default but may be set to a coderef that Type::Tiny and related modules
           will use to dump data structures in things like error messages.

           Otherwise Type::Tiny uses it's own routine to dump data structures.  $DD may then be
           set to a number to limit the lengths of the dumps. (Default limit is 72.)

           This is a package variable (rather than get/set class methods) to allow for easy
           localization.

BUGS

       Please report any bugs to <http://rt.cpan.org/Dist/Display.html?Queue=Type-Tiny>.

SUPPORT

       IRC: support is available through in the #moops channel on irc.perl.org
       <http://www.irc.perl.org/channels.html>.

SEE ALSO

       Type::Tiny::Manual, Type::API.

       Type::Library, Type::Utils, Types::Standard, Type::Coercion.

       Type::Tiny::Class, Type::Tiny::Role, Type::Tiny::Duck, Type::Tiny::Enum,
       Type::Tiny::Union, Type::Tiny::Intersection.

       Moose::Meta::TypeConstraint, Mouse::Meta::TypeConstraint.

       Type::Params.

AUTHOR

       Toby Inkster <tobyink@cpan.org>.

THANKS

       Thanks to Matt S Trout for advice on Moo integration.

COPYRIGHT AND LICENCE

       This software is copyright (c) 2013-2014, 2017 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.