From: sto.mar@...
Date: 2013-03-12T04:59:09+09:00
Subject: Re: Confusion with block local variable declaration with block variable declaration within the pipe

Am 11.03.2013 13:22, schrieb Love U Ruby:
> 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.

Because you did not try to append nil to a string!

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


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