[ruby-core:19131] Re: Autoload and class definition

"And class definition checks if the class is already defined, to reopen it"

Sure, and that's my point. It checks if it is already defined. If it is not, which is the case since load_c doesn't define C directly in F class, it creates a new class. It doesn't raise NameError.

The example is NOT equivalent with

autoload(:C, "load_c")
C # => NameError

If you try it you get value 1, not a NameError because lookup algorithm for constant read is different from the one used in class definition:

C:\Temp>type load_c.rb
module M
  C = 1
end

class F
  include M
end

C:\Temp>irb
irb(main):001:0> class F
irb(main):002:1>   autoload(:C, "load_c")
irb(main):003:1>   C
irb(main):004:1> end
=> 1
irb(main):005:0> exit

C:\Temp>irb
irb(main):001:0> class F
irb(main):002:1>   autoload(:C, "load_c")
irb(main):003:1>   class C
irb(main):004:2>   end
irb(main):005:1> end
NameError: uninitialized constant F::C
        from (irb):3
irb(main):006:0>

Tomas

-----Original Message-----
From: Nobuyoshi Nakada [mailto:[e-mail]]
Sent: Sunday, October 05, 2008 8:28 AM
To: [e-mail]
Subject: [ruby-core:19129] Re: Autoload and class definition

> Now, let's do the same using constant auto-loading instead:
>
> class F
>   autoload(:C, "load_c");
>
>   class C  # => uninitialized constant F::C (NameError)
>   end
> end
>
> It seems that autoload repeats the same constant resolution
> semantics that triggered it (otherwise C would be found in M
> and TypeError would be raised), yet it raises error if the
> constant is not found. This seems to be a bug. I would expect
> no exception.

That autoload declares C must be defined in load_c, but it
isn't.  And class definition checks if the class is already
defined, to reopen it.

Your example is same as:

  autoload(:C, "load_c")
  C # => NameError

--
Nobu Nakada
c