From: patrick-may@... (Patrick May)
Date: 2002-09-13T14:02:20+09:00
Subject: Re: not grasping the method overloading/multi-dispatch thing

Paul Brannan <pbrannan@atdesk.com> wrote in message news:<20020912182059.X25425@atdesk.com>...
> One possibility would be to make it hard to make a method that takes
> only one type as a parameter:
>
> [example snipped]
>
> This would probably deter people from writing non-generic code, but
> still allow them to do so.

Well, that's the situation we're in now -- you can write methods that
check the types of their arguments, but it is difficult.  Making it
easy, then making it difficult doesn't make sense to me.

The real api designer question is:

Is this behaviour, conditional execution on type, something we should
encourage?

Conditionals on type are a smell of code that could be moved from the
users of a class to the class itself.  It is easy enough to write
these types of methods, and I think it leads to simpler, more flexible
code.

Think about all those useful, but slightly obscure, methods that ruby
has:

aString.ljust
aString.reverse
array.uniq
hash.update
integer.downto

I doubt if everything in the standard library started as a part of the
distribution.  Many useful functions likely began as additions written
by users of Ruby, and were later submitted to matz as RCR's.

Ruby's excellant design is not only the product of forward thinking,
but also the by-product of encouraging people to make these kinds of
changes.  So, why add easy static typing to ruby -- how many of these
opportunities will we miss?  How much will we slow the pace of
innovation?

That is my concern.

~ Patrick