Re: Pattern for configuring child objects.

On Thu, 23 Feb 2012, Bill Moseley wrote:

> Another common class I seem to have is one that maintains a list of "child"
> objects.  For example, I might pass in a path to a directory and the class
> creates one object for each file in the directory.
>
> package Directory:
> use Moose;
>
> has directory => ( ... );
> has debug => ( isa => 'Bool', ... );
> has file_list => ( traits => ['Array'], lazy_build => 1, ... );
>
> sub _build_file_list {
>     my $self = shift;
>     return [ map { $self->file_class->new( { debug => $self->debug, path
> => $_ } ) } $self->files_in_dir ];
> }
>
> Not problem copying a few attributes like that, but some of my real child
> objects have much more config to pass around.
>
> Other more clever ideas?

I've thought about this a little. Building something like Class::Container 
(https://metacpan.org/release/Class-Container) would be way, way easier 
with Moose.

You could do it as a parameterized role, maybe:

   with 'Role::Container' =>
       { contains => { bar => 'Foo::Bar', baz => 'Baz::Object' } );

This would introspect the relevant classes and either add attributes or 
some sort of BUILD or BUILDARGS wrapper to record the relevant parameters 
and save them for later.


-dave

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