From: matz@... (Yukihiro Matsumoto)
Date: 2002-08-06T15:37:14+09:00
Subject: Re: block , yield and proc?

Hi,

In message "block , yield and proc?"
    on 02/08/06, "Shashank Date" <ADATE@kc.rr.com> writes:

|I  am experimenting with code using blocks, yield and proc in Ruby (1.7.2
|mswin32) and discovered three different ways of expressing the same idea:

First, you have to learn several tips:

  (a) block parameter |v| means takes everything in a single variable,
      which is better described as |*v|.

  (b) "call" requires exact number of required argument, whereas
      "yield" fills nil for fewer arguments and ignores too much
      arguments.

|Q1: Why does the following code :

This is caused by (b).

|Q2: What exactly is the semantic difference between using a bloc parameter
|(with &) and a yield?

This is answered almost by (b).  In addition, a block argument
(&block) creates one more object.

|Q3: And what about using Proc?

No difference, except for appearance.

							matz.