From: Robert Klemme <shortcutter@...>
Date: 2006-12-26T04:50:04+09:00
Subject: Re: Strange about Array#each_index

On 25.12.2006 20:22, Li Chen wrote:
> c�me wrote:
> 
>> Try it in a program file : irb use to print the "inspect" method of
>> every object used.
> 
> It looks like there are some differences between running a script from 
> irb and the command line. I should try them both before I post questions 
> in the future.

I am not sure whether you understood the point properly - please ignore 
if I'm just adding line noise.  Yes, there are differences in the 
treatment of local variables.  IRB also prints out the result of 
invoking #inspect on each expression that you pass on to evaluation. 
Other than that each_index behaves identically in IRB and in a script. 
In your first posting you say

> According to the above Array#each_index will return only the index for
> each element: 0,1,2.

and

> But when I paste the codes and run on my XP I find Ruby returns both
> indexes and values. Do I miss something?

each_index always *returns* the receiver (i.e. the Array or whatever you 
invoke that method on) and each_index *passes* every index to the block. 
  The fact that you see both is just a consequence of the fact that both 
routes eventually print something to the screen.  So the crucial bit to 
distinguish is *passing* values to a block and *returning* values from a 
  method.

Kind regards

	robert