George Hartzell > MooX-StrictConstructor-0.006 > MooX::StrictConstructor

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Module Version: 0.006   Source  

NAME ^

MooX::StrictConstructor - Make your Moo-based object constructors blow up on unknown attributes.

VERSION ^

version 0.006

SYNOPSIS ^

    package My::Class;

    use Moo;
    use Moo::StrictConstructor;

    has 'size' => ( is => 'rw');

    # then somewhere else, when constructing a new instance
    # of My::Class ...

    # this blows up because color is not a known attribute
    My::Class->new( size => 5, color => 'blue' );

DESCRIPTION ^

Simply loading this module makes your constructors "strict". If your constructor is called with an attribute init argument that your class does not declare, then it dies. This is a great way to catch small typos.

STANDING ON THE SHOULDERS OF ...

Most of this package was lifted from MooX::InsideOut and most of the Role that implements the strictness was lifted from MooseX::StrictConstructor.

SUBVERTING STRICTNESS

MooseX::StrictConstructor documents two tricks for subverting strictness and avoid having problematic arguments cause an exception: handling them in BUILD or handle them in BUILDARGS.

In MooX::StrictConstructor you can use a BUILDARGS function to handle them, e.g. this will allow you to pass in a parameter called "spy" without raising an exception. Useful? Only you can tell.

   sub BUILDARGS {
       my ($self, %params) = @_;
       my $spy delete $params{spy};
       # do something useful with the spy param
       return \%params;
   }

Because BUILD methods are run after an object has been constructed and this code runs before the object is constructed the BUILD trick will not work.

BUGS ^

Inheritance

A class that uses MooX::StrictConstructor but extends another class that does not will not be handled properly. This code hooks into the constructor as it is being strung up (literally) and that happens in the parent class, not the one using strict.

Subverting strictness

MooseX::StrictConstructor documents a trick for subverting strictness using BUILD. This does not work here because strictness is enforced in the early stage of object construction but the BUILD subs are run after the objects has been built.

SEE ALSO ^

AUTHOR ^

George Hartzell <hartzell@cpan.org>

COPYRIGHT AND LICENSE ^

This software is copyright (c) 2013 by George Hartzell.

This is free software; you can redistribute it and/or modify it under the same terms as the Perl 5 programming language system itself.

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