From: Robert Klemme <shortcutter@...>
Date: 2011-01-18T18:27:35+09:00
Subject: Re: Why Ruby Does Not Support Method Overloading?

On Tue, Jan 18, 2011 at 2:09 AM, Su Zhang <zhangsu@live.com> wrote:
> Method overloading is ideally a feature only for statically typed
> language, in which the binding of method names can be easily made at
> compile time. Function/method names as well as the statically typed
> formal parameters are all parts of the formal names used during early
> binding. However, with a dynamically typed language (especially those
> who have a method dispatch implementation similar to Smalltalk), only
> the method name is considered part of the formal message content during
> method dispatch (late binding).

There is also a more fundamental reason to consider disallowing method
overloading with different argument signatures: each method that
shares the same name (identifier) should do the same.  If however
arguments have different types methods cannot do the same - strictly
speaking.  Of course, this is an extreme point of view but you have to
ask yourself where you draw the line for "same".

In languages with interfaces (e.g. Java) ideally all appropriate
argument types implement the same interface and you need only one
method anyway - or all argument types inherit from a common base
class.

In Ruby however which has duck typing you can pass in anything as long
as "anything" responds to all methods needed - hence there is less
demand for overloading.  You can do

class IntSum
  def initialize; @s = 0; end

  def add(x)
    @s += x.to_int # or x.to_i
  end
end

where you would need multiple methods for different argument types in
other languages.

Kind regards

robert

-- 
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