From: Ryan Pavlik <rpav@...>
Date: 2003-11-05T10:03:33+09:00
Subject: Re: Managing metadata about attribute types

On Wed, 5 Nov 2003 09:38:16 +0900
Simon Kitching <simon@ecnetwork.co.nz> wrote:

> Hi,

<snip>

> I was wondering if there were any other Ruby projects which have faced
> this problem and come up with solutions? I would rather steal a solution
> than invent one :-)

Yep.  I'll take this opportunity to shamelessly plug some modules.  I
do this in Mephle.  First, I use the StrongTyping module and write new
attr_ functions, so I can do this:

  attr_accessor_typed String, :foo, :bar

Now #foo= and #bar= complain if they don't get a String.  Even better,
I can use StrongTyping's type querying on foo= and bar= to get what
they take, if I need to.

Next, I use the MetaTags module for actually tagging what attributes
exist:

  class_info <<-DOC
    !Class: Foo

    !attr foo: Foo
    !attr bar: Bar: This is an optional description of bar.
  DOC
  class Foo
     :
  end

Now I can ask for information about the Foo class and look through the
attributes that way.

It works... I generate UIs from this information... and I'm working on
some tools to eliminate redundancy and required typing.

hth,

-- 
Ryan Pavlik <rpav@mephle.com>

"Mmm! Power lines and paint chips! My childhood rocks!" - 8BT