From: Emil Ong <emilong@...>
Date: 2001-07-20T23:07:28+09:00
Subject: [ruby-talk:18185] Re: Opaque constants? (in C?)

Great, thanks!  BTW, I'm planning on using capitalized constants, but I
was following the lead of true and false because those were the only
opaque constants that I knew.

Thanks again,
Emil

On Fri, 20 Jul 2001, Kenichi Komiya wrote:

> 
> Hi,
> 
> From: Emil Ong <onge@mcs.anl.gov>
> Subject: [ruby-talk:18150] Opaque constants? (in C?)
> Date: Fri, 20 Jul 2001 07:16:35 +0900
> 
> > Is it possible to define opaque constants in ruby similar to true and
> > false?  That is, if you were using irb and you wanted the value of the
> > constant 'my_const', you would get something like this:
> 
> You can make an object 'opaque' by defining "inspect" as a
> singleton method, so that it always returns "it's name".  
> 
> So, if you can live with captalized constant...
> 
>   irb(main):001:0> MY_CONST = Object.new
>   #<Object:0x4028bfb8>
>   irb(main):002:0> MY_CONST
>   #<Object:0x4028bfb8>
>   irb(main):003:0> def MY_CONST.inspect; "MY_CONST".freeze; end
>   nil
>   irb(main):004:0> MY_CONST
>   MY_CONST
> 
> You can chose to define a uncapitalized pseudo constant (a
> method always return the same object).
> 
>   class Object
>     obj = Object.new
>     define_method(:my_const) { obj }
>   end
>   def my_const.inspect
>     "my_const".freeze
>   end
> 
> In many situations, it works as if it is constant.  But, using
> non-standard naming convention like this decrease readability,
> IMHO.
> 
> > Moreover, can I do it from C?
> 
> MY_CONST version in C.
> 
>   VALUE my_const = rb_obj_alloc(rb_cObject);
>   rb_define_singleton_method(my_const, "to_s", my_const_to_s, 0);
>   rb_define_global_const("MY_CONST", my_const);
> 
> Best Regards,
> Kenichi Komiya.
>