From: Victor Deryagin <vderyagin@...>
Date: 2011-07-24T20:30:54+09:00
Subject: Re: Exclusive operator in ruby

"amir e." <aef1370@gmail.com> writes:

> Hi
> I am C++ programmer and I start ruby programming about 1 month.I have 2
> questions:
> 1 - I don't understand what is these operators : === and !== . please
> give an example.

'Object#===' method is the same as 'Object#==', but is often overridden
by the descendants for convenience (mainly to provide meaningful
semantics in 'case' statements). For example, Regexp class makes it an
alias to its '=~' method, so you can do things like this:

a = "HELLO"
case a
when /^[a-z]*$/; :lower_case
when /^[A-Z]*$/; :upper_case
else;            :mixed_case
end          #=> :upper_case

(a !== b), as you might expect, is equivalent to !(a === b).

> 2 - As respect , Ruby is very comfort language , can we define function
> like this :
> def myFunc( a=0 , b=1 , c=2 )
> d = a+b+c
> end
>
> and call this function with only third argument like :
> myFunc( , , 10).

You can not do this (ruby does not support keyword arguments), but it is
possible to achieve similar result by passing your arguments as hash:

def my_func(hsh)
  hsh = {:a => 0, :b => 1, :c => 2}.merge hsh
  hsh[:a] + hsh[:b] + hsh[:c]
end

my_func({:c => 10})   #=> 11