From: Paul Brannan <pbrannan@...>
Date: 2002-06-25T02:11:07+09:00
Subject: Re: No exceptions from String#to_i

On Tue, Jun 25, 2002 at 12:27:03AM +0900, Yukihiro Matsumoto wrote:
> Functional style methods are more strict than their OO style
> counterpart in general.

Unfortunately, it's not possible to do this with user-defined data
types.  If I have a String-like class with a to_i method that I want to
return 0 on error, then I can do that, but then Integer() will also
return 0 on error.  If I want Integer() to raise an exception on error,
then to_i must also raise an exception on error.

It's not good to have a standard library feature that user libraries
cannot emulate.

Paul