From: Julian Snitow <vangczung@...>
Date: 2003-05-28T06:42:14+09:00
Subject: Re: Constant Definitions and Hiding

On Tue, 27 May 2003 13:32:13 +0200, Robert Klemme wrote:

> 
> "Julian Snitow" <vangczung@yahoo.com> schrieb im Newsbeitrag
> news:pan.2003.05.27.10.23.28.960550@yahoo.com...
>> On Tue, 27 May 2003 09:55:03 +0200, Robert Klemme wrote:
>>

[snipsnip]

>> > Hm, maybe it's a question of expectations.  OTOH I found it surprising
>> > that defining a singleton method that had been defined as a singleton
>> > method issues a warning, too.  But I can see, that it's reasonable to
> warn
>> > about this.
>>
>> I submit that referring to an unqualified BAR usually indicates that the
>> programmer probably intended for the local BAR to be used, as opposed to
>> specifying Foo::BAR.  I can think of several examples in which I might
>> legitimately want to extend a subclass's behavior by setting a new BAR,
>> and since Ruby already offers a clear, concise way to specify which of
> the
>> two cases you want, I think it's better to err on the side of
>> extensibility.
> 
> ... leading you to which conclusion?  Sorry, I don't get what you indend
> to say be "it's better to err on the side of extensibility".

By "extensibility" I mean the ability to change as much of a (sub)class's
behavior at runtime without being warned; I favor the "trust the
programmer" approach of permitting the definition of FooSubClass::BAR, on
the theory that the implicit/explicit scoping rules are there for a
reason, and that defining  class Bar < Foo; BAR = "something else"; end,
doesn't wipe out the definition of Foo::BAR.  Any unintended side-effects,
then, are localized, and will be caught during the debugging of class Bar.

You'll note that if you redefine Foo::BAR in two different places, you're
already warned, so your proposed warning can't be justified on the grounds
that Bar::BAR would interfere with the operation of class Foo.  (*whew!* ;-)

> 
>> (Of course, since I'm aesthetically biased against the use of CONSTANTS
> inside a
>> class definition anyway, my opinion in this matter is "for entertainment
>> purposes only"! ;-)
> 
> You might be pleased to hear that I found your comments entertaining and
> interesting. :-)
> 
Thanks! :)

Cheers,
Julian