[self-interest] parent slot lookups

Jecel Assumpcao Jr jecel at merlintec.com
Mon Apr 7 22:59:16 UTC 2003

On Sunday 06 April 2003 02:26, Steve Dekorte wrote:
> When Self follows an inheritance chain, will it activate methods in
> parent slots? That is, if set an Object to have a parent slot
> containing a method(instead of another object) that returns the
> object that I want to lookup to continue in, will it work?

Dave has already answered "no", but I would like to consider the 
practical complications of such a scheme.

Does the method take any arguments? If so, when invoked from the lookup 
routine instead of a regular program then what will that argument be? 
If not, then won't the method always reply the same object (same thing 
as a data slot)?

You might think that a no argument method can return different values 
since it can send further messages (which is correct) but then you run 
into a different problem: what if these further messages also need 
lookup via the very "parent method" we are trying to evaluate?

And all this supposing that each object has a single parent data/method 
slot. With multiple parents there will be a fantastic number of ways 
that things can be combined and it will nearly always be impossible to 
understand what is going on.

A far better way to organize things is to create a proper reflective 
layer. See CoDA for Smalltalk as an example in which seven different 
kinds of meta-objects allow you to change any aspect of message passing 
and inheritance in a modular and understandable way:


-- Jecel
P.S.: thanks for the "naked objects" link - it is actually more similar 
to the eToys viewers in Squeak than outliners in Self

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