NAME

Declare::Constraints::Simple::Library::General - General Constraints

SYNOPSIS

  # custom error messages
  my $constraint = 
    And( Message( 'You need to specify a Value', IsDefined ),
         Message( 'The specified Value is not an Int', IsInt ));

  # build results
  my $valid   = ReturnTrue;
  my $invalid = ReturnFalse('Just because');

DESCRIPTION

This library is meant to contain those constraints and constraint-like elements that apply generally to the whole framework.

CONSTRAINTS

Message($message, $constraint)

Overrides the "message" set on the result object for failures in $constraint. For example:

  my $message = 'How hard is it to give me a number?';
  my $constraint = Message($message, IsNumber);

  my $result = $constraint->('duh...');
  print $result->message, "\n";

The "Message" constraint overrides the error message returned by it's whole subtree, however, the "Message" specification nearest to the point of failure will win. So while this

  my $constraint = Message( 'Foo',
                            IsArrayRef( Message( 'Bar', IsInt )));

  my $result = $constraint->(['I am not an Integer']);
  print $result->message;

will print "Bar", this

  my $result = $constraint->('I\'m not even an ArrayRef');
  print $result->message;

will output "Foo".

Scope($name, $constraint)

Executes the passed $constraint in a newly generated scope named $name.

SetResult($scope, $name, $constraint)

Stores the result ov an evaluation of $constraint in $scope under $name.

IsValid($scope, $name)

Returns a true result if the result $name, which has to have been stored previously in the scope named $scope, was valid.

ReturnTrue()

Returns a true result.

ReturnFalse($msg)

Returns a false result containing $msg as error message.

AUTHOR

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

LICENSE AND COPYRIGHT

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