From: Dave Thomas <Dave@...>
Date: 2002-08-28T04:12:06+09:00
Subject: Re: compile time type checking

"Volkmann, Mark" <Mark.Volkmann@AGEDWARDS.com> writes:

> I'm curious how some of you that have written real applications in Ruby have
> dealt with this. Don't you have problems where an application crashes on a
> user because the wrong type of object gets passed to a method and it tries
> to invoke a method of the object that it doesn't have?
... 
> I love Ruby syntax, but this issue may be one that keeps many people using
> Java instead.

But Java has run-time type checking as well. Consider an average
running Java program. How many objects are extant? 1,000? 2,000? How
many variables do you have? 20? 30?  So, where are all the other
objects? In collections. And how do you get to them? By casting at
every access. The type gets discovered at run time.

How many class cast exceptions do you see in Java? In reality, not
many.

In the same way, I don't often see the wrong kind of object being used
in Ruby. However, to ensure that, I have to exercise the various paths
through the code, so I rely on unit tests to give me the confidence
that my code is reasonable.


Cheers


Dave