From: georgesawyer <georgesawyer2@...>
Date: 2005-01-09T10:46:30+09:00
Subject: Re: Ruby design question: lazy construction of object graph containi

"itsme213" <itsme213@hotmail.com> Jan 6, 2005 at 06:59 AM wrote:
>Consider [a kind of] Ruby object graph being constructed .... The
>graph gets built monotonically; i.e., all slots are either
>uninitialized, or initialized, but not modified once initialized.

I recommend Ruby constants.

>I would like to force resolution of (selected or all) unresolved
>references, either:
>a) at a time of my choosing (raising exceptions if needed), or
>b) incrementally whenever a given reference becomes resolvable, or
>c) when something is done with that reference, i.e. some method
>   [is] invoked on it ....

>I can assume that 'nil' is a distinguished sentinel value
>indicating an uninitialized slot, ... but I don't know how much
>that will help .... [E]ven nil has a whole heap of defined
>methods. I can change any of the assignment methods as needed.

Or perhaps not nil, as below.

>What would be a good way to accomplish this? I was thinking I
>could create a trail of proc-like things representing bits of
>suspended computation (a bit like 'futures')

Cool!

>but can't really figure ... if it would be a good approach. Do
>continuations offer some magic that would help?

The following dynamic capability can support, I believe,
your graph:

          =>class A ;end
          =>A::B =5
          =>print A.const_defined?( :B) ;A.const_defined? :C
truefalse

          =>class A ;remove_const( :B) ;end
          =>A.const_defined? :B
false

The class Module is the parent class of the class Class.  Module
defines these methods.