From: "Carlo E. Prelz" <fluido@...>
Date: 2013-01-22T04:49:54+09:00
Subject: Re: Enumerator usage

	Subject: Enumerator usage
	Date: Tue 22 Jan 13 04:20:57AM +0900

Quoting David Richards (lists@ruby-forum.com):

> I don't understand the following:
> 
> 3.times { |i| puts(i) }  # ok
> 3.times.class  # Enumerator
> n = 3.times
> n.class  # Enumerator
> n { |i| puts(i) }  # error!?
> 
> To a new Ruby student this error seems 'conceptually wrong'.

Ruby documentation is well-made. Make good use of it!

If you type 

ri Integer#times

you will read:

--8<----8<----8<----8<----8<----8<----8<----8<----8<----8<----8<--
------------------------------------------------------------------------------
  int.times {|i| block }  ->  self
  int.times               ->  an_enumerator

------------------------------------------------------------------------------

Iterates block int times, passing in values from zero to int - 1.

If no block is given, an enumerator is returned instead.
--8<----8<----8<----8<----8<----8<----8<----8<----8<----8<----8<--

In your first example you pass a block, so it returns self. In the
second example, you do not provide a block, and an enumerator is
returned. 

Note that if you type

3.times { |i| puts(i) }.class

you will get Integer (self, in this case, is the integer 3).

What is an enumerator, then (which is returned by the Integer#times
methods when you do not provide a block)? Use the documentation: read
with care what you obtain when you type

ri Enumerator

> There just seems to be something really 'wrong' about how Ruby treats
> functions:
> 
> def f2(i)
>     puts(i)
> end
> 
> f2.class # error!?

With def you define a method of the current class (or a method of the
Object class if you are not defining your own class). You do NOT
define a variable. If you want a variable to contain the reference to
your new method, you must type

vrb=method(:f2)

and vrb will be an instance of the Method class, containing a
reference to your method.

> I'm hoping that once I understand it better
> it will start to look 'elegant' and 'beautiful', but right now it looks
> kinda 'scary' and 'repugnant'.

'scary' and 'repugnant' are two concepts that express fear. Fear is
the first enemy that has to be won on the path of growth...

Ruby is just different from what you are used to. But it works. 

> 
> Help please!
> 
> - Dave
> 
> -- 
> Posted via http://www.ruby-forum.com/.
> 

-- 
  *         Se la Strada e la sua Virtu' non fossero state messe da parte,
* K * Carlo E. Prelz - fluido@fluido.as             che bisogno ci sarebbe
  *               di parlare tanto di amore e di rettitudine? (Chuang-Tzu)