From: Greg McIntyre <greg@...>
Date: 2003-11-22T08:37:14+09:00
Subject: Re: Partial Euphoric Type Checking (Super Duck!?)

Austin Ziegler <austin@halostatue.ca> wrote:
> Why not consider doing interfaces in Ruby as bundles of DbC
> "contracts"[1]? That way, you get *dynamic* interfaces that aren't
> necessarily simplistic name-checks, which is what I'm opposed to.

I thought of that earlier when I read Sean's proposal however I
dismissed it initially because I thought it would be too much effort.
However I think it's a distinct possibility!

The "Partial Euphoric" type system T. Onoma has put forward seems to be
a little like sets of preconditions tagged with identifiers and later
applied to method paramters.

I see it as a gradient... if you put in no effort, you can have little
typechecking, if you put in a little effort, you can have a bit more,
etc. DbC is way up the deep end of the scale where you put in
substantial effort and receive substantial returns. What's more, I think
it should be up to the Ruby developer how much checking is desired.

On the effort scale, IMO:

No checking << Duck typing == Interface checking based upon method name
+ arity ("organised duck typing"?) << Interface checking based upon
method signature == Type checking in static languages << Interface
checking based upon DbC contracts

(<< means "much more than")

That's just my view of the world, maybe DbC isn't that much effort. It
certainly can give wonderful rewards: very powerful and descriptive
interfaces.

Here's a wild suggestions. What if all these levels could be
incorporated in Ruby as separate, optional, non-conflicting libraries?
Okay, maybe I should go lie down now. ;)

-- 
Greg McIntyre ======[ greg@puyo.cjb.net ]===[ http://puyo.cjb.net ]===