From: "David A. Black" <dblack@...>
Date: 2007-09-26T01:32:11+09:00
Subject: Re: Why dynamic languages for ActiveRecord..?

Hi --

On Wed, 26 Sep 2007, Phlip wrote:

> David A. Black wrote:
>
>> I'd say that the type of a Ruby object can change, but its class
>> cannot. That's based on an understanding of the object's type as a
>> kind of runtime snapshot of what the object can do and what messages
>> it understands.
>
> The inspiration there is Smalltalk, which is similarly strongly typed.

That's the proximate inspiration, though I always remember Matz
summing it up at RubyConf 2002 (I think): "Ruby is dynamic, like human
nature." :-)

> One common confusion among newbs is that weak typing == dynamic typing.

In the long run, the notion of type in Ruby is tautological: an object
is of type "The type which is the type of objects that are of this
object's type." That may be why "type" sometimes gravitates toward
being a synonym for "class" (along with the historical accident of
Kernel#type), though I think having a separate term for the changable
part is useful, and also makes sense of phrases like "duck typing".


David

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