Stevan, Dave, thanks for your input. I renamed the module. It is now available at https://github.com/monken/p5-moosex-attribute-dependent.
I also ditched the TypeConstraint thingy and implemented it myself. Took some time to figure out the Type[] magic but eventually... :-) Please tell me if you have any more suggestions or ideas. Cheers, mo Am 26.12.2010 um 16:46 schrieb Stevan Little: > Yeah, I have to agree, my first reaction was based on the examples and tests, > but upon further review of the code I think Dave is right. > > You see, in Moose a type constraint acts upon the value in the attribute and > knows nothing of the object that contains it. This is part of what makes > Moose type constraints so useful outside of Moose as well as inside. > > I am not actually sure you need to include types in this, much of what you > are using Moose::Meta::TypeConstraint could easily be written as a stand > along "Dependency" class. Additionally by adding your types to the global > type registry in MooseX::Dependency::Types you are making them accessible to > everyone as proper Moose types, which they really aren't since they require a > specialized set of arguments. > > I think you could easily remove the type-system elements of this and create a > nice and useful MooseX:: module that handles the dependencies between > attributes. > > I do like the Any[], All[], etc. though, so I think you should keep that. > > - Stevan > > On Dec 26, 2010, at 10:17 AM, Dave Rolsky wrote: > >> On Sun, 26 Dec 2010, Stevan Little wrote: >> >>> Looks good, however I think MooseX::Depedency is too general a name, how >>> about MooseX::Types::Dependent::Types? >> >> I don't think this is what dependent types means. > > No, but kinda. Dependent types are a type of type system (hehe) that are > dependent upon runtime values, the example on wikipedia > (http://en.wikipedia.org/wiki/Dependent_type) is kinda nice : > > An example is the type of n-tuples of real numbers. This is a dependent type > because the type depends on the value n. > > So in (psuedo) Moose land that might be something like: > > subtype IntTuple => as_dependent_type { Tuple[ type => 'Int', size => $_[0] > ] }; > > Where '$_[0]' is parameterizable for the given type, like so: > > has small_tuple => ( ... isa => IntTuple[ 2 ] ... ); > has big_tuple => ( ... isa => IntTuple[ 20 ] ... ); > > This example wouldn't of course help if you wanted access to $self, but the > idea could be expanded upon perhaps to work in this case. > > Honestly though, I think this really overcomplicates the type system and is > much more difficult to use and understand then something more like what > Moritz has created here. > > >> Also, I'm not sure this has anything to do with types at all. This is really >> about whether a value is _required_. >> >> Maybe MX::Attribute::Dependent or something like that. >> >> >> -dave >> >> /*============================================================ >> http://VegGuide.org http://blog.urth.org >> Your guide to all that's veg House Absolute(ly Pointless) >> ============================================================*/ >
