From: Martin DeMello <martindemello@...>
Date: 2002-12-04T08:48:27+09:00
Subject: Re: Ruby Book for People Who Aren't (Yet) Programmers

Mauricio Fern?ndez <batsman.geo@yahoo.com> wrote:
>> puts 5.0/3 # -> 1.666666667
>> 
>> !Note: Each operator is actually several different methods, depending on
>> the type of its left hand operand. The two we just saw are, in full,
>> Integer#/ and Float#/. This is sometimes referred to as 'operator
>> overloading'.
> 
> Isn't it rather just an example of polymorphism (dynamic dispatch based
> on the type of the receiver)? Anyway I don't think these terms need to be
> introduced in a tutorial.

I was trying to avoid the term 'polymorphism' - 'operator overload' at
least looks like English :) And we do have to introduce at least the
concept, to explain what's going on. How about this:

!Note: The behaviour of an operator depends on the type of its left hand
operand. This is because an operator is actually a method of the left
hand object. Thus, (5 / 3) and (5.0 / 3) involve two different
operators, whose full names are Fixnum#/ and Float#/ (read 'the /
operator of type Fixnum' and similarly for Float). 

Maybe we should say 'class' instead of 'type' from the beginning, at
that, and use the word type only informally, as a loose synonym for
'class'.

martin