From: dblack@...
Date: 2002-10-24T20:21:54+09:00
Subject: Re: Things That Newcomers to Ruby Should Know (10/16/02)

Hi --

On Thu, 24 Oct 2002, William Djaja Tjokroaminata wrote:

> If a person has a C++ background, then probably the concept of creation of
> intermediate object is troubling, because one of the many advices in C++
> books is something like:
>
>     "When you pass an argument to a function, in general it is better to
> pass it by reference instead of pass by value, because pass by value can
> be much more expensive as it may involve the creation of an intermediate
> object, while pass by reference will not."  (To avoid modifying the
> original object then the "const" type specifier is used.)
>
> Therefore, a person with a C++ background, who is used to avoiding the
> creation of unnecessary intermediate objects, will be surprised that Ruby
> does it *all the time* in its '+=' operator.  (Furthermore, the creation
> of equivalent intermediate objects may even be more "expensive" in Ruby
> than in C++ in absolute terms.)

I don't think "a += 'str'" (or whatever) is creating an intermediate
object though, at least not in the sense that I understand the term.
It's just performing an assignment, not doing anything extra.

> Therefore, this type of question is, in my opinion, usually not originated
> by practicality concern as much as caused by the differences in "school of
> thoughts" in the programming world.  C++ is more about
> (computer's) performance, while Ruby is more about (programmer's) fun. :)

I won't argue with that :-)  though it's important to remember that
there's nothing secret or subterranean about += in Ruby.  It's just a
way of performing an assignment -- so if that isn't what one wants
(for performance or other reasons), one has all the information
necessary to decide not to use it.


David

-- 
David Alan Black
home: dblack@candle.superlink.net
work: blackdav@shu.edu
Web:  http://pirate.shu.edu/~blackdav