From: Josh Cheek <josh.cheek@...>
Date: 2011-01-28T06:01:37+09:00
Subject: Re: why is overloading invalid in ruby.

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On Thu, Jan 27, 2011 at 1:22 PM, Ted Flethuseo <flethuseo@gmail.com> wrote:

> I don't understand why when I try to overload I get an error. Can I
> overload somehow?
>
> #!/usr/bin/env ruby
>
> class Summer
>  def sum(x)
>    return x + 2
>  end
>
>  def sum(x,y)
>    return x + y
>  end
>
>  def sum(x,y,z)
>    return x + y + z
>  end
> end
>
> s = Summer.new
> puts s.sum(3)
>
> ERROR:
> ArgumentError: wrong number of arguments (1 for 3)
>
> method sum  in summer.rb at line 18
> at top level  in summer.rb at line 18
>
>
> Ted
>
> --
> Posted via http://www.ruby-forum.com/.
>
>

Ruby methods don't really have signatures, so overloading would be quite
difficult.

Disregarding your first sum, which adds 2, for some unknown reason, I would
write the method like this:

def sum(*numbers)
  sum = 0
  numbers.each { |number| sum += number }
  sum
end

Okay, I would probably actually write it like this, which is the same thing,
but less accessible to people who haven't encountered inject or reduce
before.

def sum(*numbers)
  numbers.inject { |sum,number| sum + number }
end

It could then be called with any number of arguments and types

sum 1               # => 1
sum 1 , 2           # => 3
sum 5 , 9 , 10      # => 24
sum 8 , 8 , 16 , 32 # => 64
sum 1.5 , 2.3       # => 3.8

In fact, it is flexible enough to take non-numeric types, though you
probably wouldn't ever use such a thing.

sum 'a' , 'b'       # => "ab"
sum [1,2] , [3,4]   # => [1, 2, 3, 4]

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