From: Eero Saynatkari <eero.saynatkari@...>
Date: 2006-08-12T08:44:22+09:00
Subject: Re: Beginner's question: assigning same value to many variab

Alex Khere wrote:
> I'm just starting out in programming, using Ruby to learn.
> 
> I'm trying to write a short program that will use a handful of 
> variables, and I want to be sure that all of the variables start with 
> the value '' (strings of zero length).
> 
> Is there a way to list all of the variables on a single line and set 
> them to the same value? I tried using commas to seperate, but that 
> didn't work.
> 
> I also tried creating an array with all of the variable names and then 
> using "arrayname.each do |name|" to cycle through the assignment, but 
> since the varibles hadn't been defined, I got an "undefined local 
> variable or method" error (at least, I think that's why I got an error).

In ruby there are no statements, just expressions. Therefore:

 @a = @b = 0

The one caveat, though, is that the references are the same
which means that, for example, assigning "hello" this way
might lead to some confusing results.

Some alternatives include:

 @a, @b = 0, 0

 @a, @b = Array.new(2) {"Hello"}

Another popular idiom is to defer the initialisation to the
point of first use of the variable. For this the || operator
is often used:

 do_something_with(@a || default_value)

 do_something_else_with(@b ||= other_default)

The latter operator is shorthand for (@b = @b || default) which
will also assign the default to @b for future use.


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