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Declare::Constraints::Simple::Library::General.3pm

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.

SEE ALSO

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

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.