From: "Y. NOBUOKA" <nobuoka@...>
Date: 2010-11-11T21:10:25+09:00
Subject: Re: what's an object?

Did you recognize the difference between a method and a Method object?
 They are quite different.  A Method object is a object which wrap a
method that is bound to a specific object.

> One does not need to know the internal details - such as "the 4th and
> 5th paragraphs of Section 6.1 of the Ruby Language Specification (lines
> 29-34 and 1-5 on pages 5 and 6)" - to be an effective programmer in
> Ruby.

Yes.  I agree that one does not need to know the internal details.
However, the difference between a Method object and a method is not
the internal details.

The relation between a method and a Method object in Ruby can be
compared to the relation between a function and a structure which have
a function pointer in C.

--- in C
 /**
  * here define a structure which have a function pointer
  * this structure is equivalent to the Method class in Ruby
  */
 typedef struct {
     int (*pointer)( int arg );
 } Fuction;
 /**
  * here define a function to obtain a Function structure
  */
 Function *obtain_Function( int (*pointer)( int arg ) ) {
     Function *f = malloc( sizeof( Function ) );
     f->pointer = pointer;
     return f;
 }

 /* here is a function */
 int func( int arg ) {
     return arg * 2;
 }
 /* obtain the Function structure which wrap the function *func* */
 Function *func_obj = obtain_Function( func );
---

--- in Ruby
 /* here is a method */
 def meth( arg )
     return arg * 2;
 end
 /* obtain the Method object which wrap the method *meth* */
 meth_obj = method( :meth )
---

Can you recognize the difference between a method and a Method object?
 In C, the Function structure is exactly a structure, while the
function *func* is not.  In Ruby, similarly, the Method object is a
object and the method *meth* is not.

I think that Ruby users need not know how a Method object wraps a
method, but they should know the fact that a Method object wraps a
method and a method is not a object.

Regards,

-- 
NOBUOKA Yuya