Dave Rolsky > Type > Type::Coercion



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Module Version: 0.05   Source  


Type::Coercion - A class representing a coercion from one type to another


version 0.05


  my $coercion = $type->coercion_from_type('Int');

  my $new_value = $coercion->coerce_value(42);

  if ( $coercion->can_be_inlined() ) {
      my $code = $coercion->inline_coercion('$_[0]');


This class represents a coercion from one type to another. Internally, a coercion is a piece of code that takes a value of one type returns a new value of a new type. For example, a coercion from c<Num> to Int might round a number to its nearest integer and return that integer.

Coercions can be implemented either as a simple subroutine reference or as an inline generator subroutine. Using an inline generator is faster but more complicated.


This class provides the following methods.

Type::Coercion->new( ... )

This method creates a new coercion object. It accepts the following named parameters:

$coercion->from(), $coercion->to(), $coercion->declared_at()

These methods are all read-only attribute accessors for the corresponding attribute.


Given a value of the right "from" type, returns a new value of the "to" type.

This method does not actually check that the types of given or return values.


Given a variable name like '$_[0]' this returns a string with code for the coercion.

Note that this method will die if the coercion does not have an inline generator.


This returns true if the coercion has an inline generator and the constraint it is from can be inlined. This exists primarily for the benefit of the inline_coercion_and_check() method for type constraint object.


This class does the Type::Role::Inlinable and MooseX::Clone roles.


Dave Rolsky <autarch@urth.org>


This software is Copyright (c) 2012 by Dave Rolsky.

This is free software, licensed under:

  The Artistic License 2.0 (GPL Compatible)
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