From: Daniel N <has.sox@...>
Date: 2006-11-09T21:55:20+09:00
Subject: Re: thousand ways to rome

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On 11/9/06, Robert Dober <robert.dober@gmail.com> wrote:
>
> On 11/9/06, spooq <spoooq@gmail.com> wrote:
> >
> > use map! instead
>
>
> nope,
> try to understand the difference between split(regexp), map and map!
> than decide for yourself
> Look at this for example
>
> "he, nice, guys".split(',').map!{|x| x.strip}
> why would you use map! ?
> try to put the above expression into a context
> e.g.
> x = ...
>
> Hint: using map! on unreferenced objects is quite useless.


Robert, I don't really understand what you mean.  My understanding is that
these do different things.  Can I walk through this in pseudo pseudo code to
increase my understanding;)

split the string into an unref'ed array
take the unreffed array and strip each element in place, creating a new
string at each element in the original array

Total Arrays created 2

How does this not differ from
"he, nice, guys".split(',').map{|x| x.strip}
Where, my understanding would be

split the string into an unref'ed array
take the unref'ed array, and create a new array from the result of each
element stripped.
ie. a new string object for each element put into a new array

Total Arrays created 3


What about
> x= "he, nice".split(",")
> x.map!{|x|x.strip}


split the string and assign it to an array
modify each element in place and strip the result.  (creating a new string
for each element)

try
> x.map!{|x|x.strip!}
> would you like to use this?


Nasty...  Turns the first element (with no whitespace) into nil

Have I understood the difference/similarities here or have I missed the
ball?

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