From: Sean O'Dell <sean@...>
Date: 2003-11-20T10:05:46+09:00
Subject: Re: "stereotyping" (was: Re: Strong Typing (Re: Managing metadata  about attribute types)

On Wednesday 19 November 2003 04:21 pm, Austin Ziegler wrote:
> On Thu, 20 Nov 2003 06:32:00 +0900, Sean O'Dell wrote:
> > On Wednesday 19 November 2003 01:25 pm, Austin Ziegler wrote:
> >> Since Bob is a smart programmer, he'll see in his error log:
> >>
> >>  NoMethodError: undefined method `accept' for #<File:3> from ...
> >>
> >> Well, this means that his File object doesn't know the method
> >> #accept. Therefore, he can open the source to your HTTP library
> >> and see "oh! this guy's expecting a Socket and has put accept in
> >> the wrong place!" If Bob's a really smart programmer, he'd
> >> already know that #accept is a Socket method.
> >
> > Wrong! There's no mention of the Socket object anywhere! The only
> > way he would know that is by searching the source code of OTHER
> > METHODS that call that method, then tracing back to where the
> > object that is passed in was created. Then he can see Socket.new.
>
> Not really. Since Ruby is open source, he can add a quick debug
> print:
>
>   def foo(arg)
>     $STDERR.puts arg.inspect
>
>
>   end
>
> He runs the library normally and he'll see that the incoming
> argument is a Socket. But there's also a neat

Not if it was installed as root and he's not root.

> The other point that I'll make is that I've had to deal with very
> similar debugging mechanisms in C, C++, and PL/SQL.
>
> > Also, don't make the assumption that the developer automatically
> > knows #accept belongs to the Socket object. Your familiarity with
> > Socket is causing you to discount the pain a developer feels when
> > this sort of error occurs. A developer may know NOTHING about the
> > Socket object and will not have a CLUE about #accept.
>
> I'm actually not that familiar with Socket at all. I just did what
> any Ruby developer can do in irb and discovered that Socket knows
> about #accept.

How did you do that without knowing it was Socket to begin with?  Armed only 
with the knowledge that the error was a call to #accept, how did you deduce 
it was the Socket object the method expected?

	Sean O'Dell