Declare::Constraints::Simple::Library::Base(3pm) User Contributed Perl Documentation Declare::Constraints::Simple::Library::Base(3pm)

Declare::Constraints::Simple::Library::Base - Library Base Class

  package My::Constraint::Library;
  use warnings;
  use strict;
  # this installs the base class and helper functions
  use Declare::Constraints::Simple-Library;
  # we can also automagically provide other libraries
  # to the importer
  use base 'Declare::Constraints::Simple::Library::Numericals';
  # with this we define a constraint to check a value
  # against a serial number regular expression
  constraint 'SomeSerial',
    sub {
      return sub {
        return _true if $_[0] =~ /\d{3}-\d{3}-\d{4}/;
        return _false('Not in SomeSerial format');
      };
    };
 
  1;

This base class contains the common library functionalities. This includes helper functions and install mechanisms.

Installs the base classes and helper functions into the $target namespace. The %CONSTRAINT_GENERATORS package variable of that class will be used as storage for it's constraints.

fetch_constraint_declarations()

Class method. Returns all constraints registered to the class.

Class method. Returns the constraint generator code reference registered under $name. The call will raise a "croak" if the generator could not be found.

Class method. This wraps the $generator in a closure that provides stack and failure-collapsing decisions.

Class method. The actual registration method, used by "constraint".

Note that some of the helper functions are prefixed with "_". Although this means they are internal functions, it is ok to call them, as they have a fixed API. They are not distribution internal, but library internal, and only intended to be used from inside constraints.

  constraint 'Foo', sub { ... };

This registers a new constraint in the calling library. Note that constraints have to return result objects. To do this, you can use the helper functions "_result($bool, $msg", _true() and _false($msg).

Returns a new result object. It's validity flag will depend on the $bool argument. The $msg argument is the error message to use on failure.

Returns a non-valid result object, with it's message set to $msg.

_true()

Returns a valid result object.

Sets the current failure info to use in the stack info part.

This applies all constraints in the "\@constraints" array reference to the passed $value. You can optionally specify an $info string to be used in the stack of the newly created non-valid results.

Puts $value into an array reference and returns it, if it isn't already one.

This is the internal version of the general "Message" constraint. It sets the current overridden message to $msg and executes the $closure with @args as arguments.

Applies the $constraint to @args in a newly created scope named by $scope_name.

Stores the given $result unter the name $name in $scope.

Returns the result named $name from $scope.

Returns true only if such a result was registered already.

Declare::Constraints::Simple, Declare::Constraints::Simple::Library

Robert 'phaylon' Sedlacek "<phaylon@dunkelheit.at>"

This module is free software, you can redistribute it and/or modify it under the same terms as perl itself.

2021-01-09 perl v5.32.0