From: Dan Zwell <dzwell@...>
Date: 2007-08-24T16:59:18+09:00
Subject: Re: something I just found out, am sharing (:newbish)

Axel wrote:
> Hello,
> 
>>  "*=", "/=", "&&=", "||=", and any others that I may have missed...
> 
> Can anybody tell me, where to find, what this means?
> 
> Thank you!
> 
> Axel
> 

var1 <an operator>= var2

is always equivalent to

var1 = var2 <an operator> 2

For example,

num ||= 0

is frequently used to mean "if num is nil, num = 0". The longhand is 
"num = num || 0", as "num || 0" evaluates to num if num is non-nil, and 
"0" otherwise. Good for making sure strings or numbers are initialized:
my_str ||= ""

&&= is good for making sure a group of things are all true:

result = true
expressions.each {|expr| result &&= expr}

The simpler operators are these:
a /= b
means:
a = a/b

Same goes for the others:
my_str = "hello "
my_str *= 3

is the same as:
my_str = my_str * 3

I no longer have my list of web sites I learned Ruby from, but it's 
pretty simple. Hope this helps.

Dan