Re: Possible to use coerce and auto_deref?

--- On Wed, 1/14/09, Howe, Tom (IT) <[email protected]> wrote:

> From: Howe, Tom (IT) <[email protected]>
> Subject: Possible to use coerce and auto_deref?
> To: "Sartak" <[email protected]>
> Cc: [email protected], "Yuval Kogman" <[email protected]>, "Stevan Little" <[email protected]>, [email protected]
> Date: Wednesday, January 14, 2009, 1:06 PM
> I have something like this:
> 
> subtype 'Thing'
>   => as 'Object'
>   => where { $_->isa('ThingClass') };
> 
> coerce 'Thing'
>   => from 'Str'
>   => via { ThingClass->new ( xyz=> $_ ) };
> 
> 
> has 'things' => (
>   is=>'rw',
>   isa=>'ArrayRef[Thing]',
>   lazy=>1,
>   coerce=>1,
>   auto_deref=>1,
>   default => sub { [] },
> };
> 
> 
> But if I pass in a list of strings to convert to Things, I
> get the error:
> 
> "Cannot coerce without a type coercion"
> 
> I've managed to get around it by defining a type
> 'ArrayRef[Thing]'
> 
> Eg
> Subtype 'ArrayRef[Thing]'
>   => as 'ArrayRef'
>   => where {
>         foreach (@{$_} ....
>      };
> 
> Coerce 'ArrayRef[Thing]'
>   => from 'ArrayRef'
> 
> But this means
> A) I'm essentially reimplementing ArrayRef each time.
> B) It always coerces!
> 
> It should ideally check before it coerces...
> 
> Anything I can do to improve on this?
> 
> 
> 
> 
> 
> Also, I'd like to be able to declare something like
> 
> has 'foo' => ( is=>'rw',
> delegate=> sub { Foo->instance }, handles =>[qw/x y
> z/] )
> 
> Where, if no value is passed in to foo() on construction,
> the accessor created for foo() will always trigger the
> delegate sub but will not store anything in the object in
> the way default does.
> 
> 
> I tried this ..
> 
> has 'foo' => ( is=>'rw',
> isa=>'Object', handles=> [qw/meth1 meth2
> meth3/]);
> 
> around 'foo' => sub {
>   my ($next,$self,@args) = @_;
>   if (@args) {
>     return $self->$next(@args);
>   } else {
>     return $self->$next() || Foo->instance();
>   }
> };
> 
> But got error:
> 
> Cannot delegate meth1 to meth1 because the value of foo is
> not defined...
> 
> 
> Is there some way to do this?
> 
> Thanks
> 
> Tom
> 
> 
> 
> > -----Original Message-----
> > From: Sartak [mailto:[email protected]]
> > Sent: 07 January 2009 12:39
> > To: Howe, Tom (IT)
> > Cc: [email protected]; Yuval Kogman; Stevan Little;
> [email protected]
> > Subject: Re: Possible to disable/rename meta() method
> >
> > On Wed, Jan 7, 2009 at 4:49 AM, Howe, Tom (IT)
> > <[email protected]> wrote:
> > > Would be nice to be able to optionally rename or
> prefix it.
> > >
> > > I don't think a object meta class should add
> methods to the
> > main interface unless the object specifically needs to
> expose them.
> > >
> > > So by default there could be a _moose_meta()
> method and an
> > easy way to create a meta() -> _moose_meta()
> handler if
> > required (per class). This could be a global option if
> want
> > to retain compatibility with existing modules that
> require it.
> >
> > Yes, we all agree that it would be useful to give
> users the
> > ability to rename or not install a meta. The problem
> is that
> > in quite a few places in Class::MOP, Moose, and all of
> > MooseX, we call $pkg->meta with the expectation
> that it'll be
> > there and return the metaclass.
> >
> > It's just a small design problem, one we can fix
> with enough
> > grunt work. :)
> >
> > >
> > > Thanks
> >
> > Shawn
> >
> > > Ps. How do I subscribe to the mail list?
> >
> > Send mail to [email protected].
> >
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