[ruby-core:28309] Re: [Feature #1082] add Object#singleton_class method

Hi,

2010/2/23 Kornelius Kalnbach <[e-mail]>:
>> Then, the next issue is whether Kernel#singleton_class should create
>> an eigenclass when the receiver has no eigenclass. =A0It would be better
>> to have an optional argument (singleton_class(true/false) or
>> singleton_class(:create =3D> true)?) to switch the behavior.
> I always perceived singleton classes to be transparently created in the
> background. Would it be wise to give the programmer access to its
> existence status? (I assume singleton_class(false) =3D=3D nil would behav=
e
> like a singleton_class? method.) Today, Ruby has no way of telling
> whether an object already has a singleton class, or am I wrong?

You are right, and it is why Matz wondered whether singleton_class
should create singleton classes.  If it always creates singleton
classes, obj.singleton_class is just a short form of class << obj;
self; end.  He said that it may be worth considering whether
singleton_class should provide an (optional) way to tell the existence
of a singleton class.

I think transparent creation of singleton classes is reasonable, but
it sometimes annoys me when I'm investigating the behavior of Ruby.
However, I don't come up with such a situation in a real-world
application.

--=20
Shugo Maeda