From: Love U Ruby <lists@...>
Date: 2013-03-11T21:22:37+09:00
Subject: Re: Confusion with block local variable declaration with block variable declaration within the pipe

In the "Book of Ruby" author wrote the below paragraph:

a = "hello world".split(//).each{ |x| newstr << x.capitalize } (<~~ But 
this code is not working in my `IRB`. And I think it should not. As 
`newstr` is not initialized before it's used. - Is this the reason for 
the code not to work.)

So, at each iteration, a capitalized character is appended to newstr, 
and the following is displayed...

H
HE
HEL
HELL
HELLO
HELLO
HELLO W
HELLO WO
HELLO WOR
HELLO WORL
HELLO WORLD

As we are using the capitalize method here (with no terminating ! 
character), the characters in the array, a, remain as they began, all 
lowercase, since the capitalize method does not alter the receiver 
object (here the receiver objects are the characters passed into the 
block). Be aware, however, that this code would not work if you were to 
use the capitalize! method to modify the original characters. ** This is 
because capitalize! returns nil when no changes are made so when the 
space character is encountered nil would be returned and our attempt to 
append (<<) a nil value to the string, newstr, would fail.**

I didn't catch him with ***points.

>> " ".capitalize!
=> nil
>> a =" ".capitalize!
=> nil
>> a
=> nil
>> a= 12
=> 12
>> a =" ".capitalize!
=> nil
>> a
=> nil

No error I did encounter.

Can anyone tell me what's the wrong? Does the author said wrong or my 
caught is wrong?

-- 
Posted via http://www.ruby-forum.com/.