From: Gavin Sinclair <gsinclair@...>
Date: 2004-06-29T08:01:55+09:00
Subject: Re: Is it considered Harmful?

On Tuesday, June 29, 2004, 4:04:21 AM, Sean wrote:

>> You're missing his point.
>>
>> If I call Array.new, I certainly get an array whose #initialize
>> has been called.
>>
>> But if I then do arr.class = Net::HTTP, then Net:HTTP#initialize
>> does NOT get called (e.g., to set the host name or whatever).

> Ah...I see why I haven't connected with that issue now.  I think of this as a
> "buyer beware" issue.  If you change an existing object's class, be sure you
> change it to something that understands the object it is receiving.  I think
> even #become would have these problems.

No it wouldn't.  Objects are supposed to represent data and behaviour.
#become keeps both intact.  #class= changes only the behaviour.  If
something does't work after #become, it's not because the use of
#become introduced an inconsistency.  The same cannot be said of
#class=.  That's not necessarily a point against it...

> Even using include could introduce methods to a class which didn't
> initialize instance data the way it expects.

...as this demonstrates.  Ruby contains lots of features that make it
easy to write broken programs.  #class= should be considered in that
light.  I don't see it as being very useful (stateless behaviour can
be elegantly captured by modules), but I'm sure it could be.

Gavin