Re: Scoping and locating definitions

On Sun, Jan 21, 2007 at 04:39:52AM +0900, Pit Capitain wrote:
> Jos Backus schrieb:
> >After looking at this I'm not sure how this helps me. Can you give an 
> >example
> >please?
> 
> Jos, here's your original example using import-module:
> 
[great example snipped]
> I haven't really used import-module yet, so I can't tell you much about 
> it. The code above just shows how I would try to solve your problem.
> 
> Feel free to ask again if this isn't what you wanted or if you have more 
> questions.
 
That's a great example. I understand how this could help much better now. But
I'm not sure how well this would scale if you had multiple
classes/modules/methods you'd want to restrict this way. Also, turning rot13
into a module method doesn't look like the most natural way to me because I'd
really like to be able to just add it to String. And having to add it to each
method call, while good as far a granularity goes, will cause a lot of extra
work, which is why my example used a class-based approach.

Perhaps what I'm really looking for is a way to tag classes and methods for
conditional export, such that they are only available in other classes if
specifically imported. This will almost certainly not be possible without some
language changes.

The background behind this is that I'm trying to sell Ruby at work as a viable
alternative to Perl/Python, and this lack of explicit import/export controls
is seen as a weakness. As one colleague put it "How do I find out where rot13
is defined? Finding it in Python is straightforward (because classes and
functions have to imported explicitly) but in Ruby it is not. This poses a
long-term readability problem.".

(My apologies for the poor description of the issue as I see it. I'm clearly
not a language designer.)

Thanks for your excellent (as always) suggestions, Pit.

-- 
Jos Backus
jos at catnook.com