From: Austin Ziegler <halostatue@...>
Date: 2005-05-07T02:28:25+09:00
Subject: Re: Prove me Wrong! Re: RCR 303: nil should accept missing methods

On 5/5/05, John Carter <john.carter@tait.co.nz> wrote:
> On Fri, 6 May 2005, Alexey Verkhovsky wrote:
>> John Carter wrote:
>>> A very simple and generic way of improving the reliability of
>>> Ruby programs is to implement the NullObject pattern by allowing
>>> nil to accept all and every method instead of throwing a
>>> NoMethodError.
>> I, for one, would rather see it throwing an error as it is now.
>> Dead programs don't tell lies.
> I would suggest next 5 times you have a nil class throws
> NoMethodError crash, just add this at the head of your program...

No. I can tell you from experience over the last four days that I
have fixed no fewer than five *real* bugs in PDF::Writer that would
have resulted in the incorrect generation of PDF output had I done
this. Probably even created a PDF that would crash any PDF reader
out there.

> If, your program then works correctly, then I am right.

This will happen in only a few applications; I would argue it will
never happen in anything that has to communicate with the outside
world.

> If, your still program thows an exception or reports an error, but
> perhaps a slightly different point, then I am still right, namely
> this change doesn't hide bugs.

Yes, it does, at least with PDF::Writer. The output for PDF has to
be correct. And in this case, PDF::Writer would simply do the wrong
thing.

-austin
-- 
Austin Ziegler * halostatue@gmail.com
               * Alternate: austin@halostatue.ca