[Edu-sig] re: Does edu-sig extend to Jython

[Arthur]

Patrick writes -

> Checking via isinstance() shouldn't be too difficult. But it may not even
>benecessary.


No. And would work fine, I'm sure, if I wasn't doing as much experimentation
and on the fly kind of stuff as I go. Even if a bit messy, at least I know I
don't need to worry about this kind of thing as a performance issue of
significance, if I can limit the isinstance checking to the initialization
routine. I *am*
sensitive to trying to keep that kind of thing out of any update cycle where
possible,
as the app is graphical and dynamic and performance can be an issue.

Perhaps I am just being somewhat lazy in my approach - and I need to be
doing more of this upfront as I go along.

>
> > So, I am beginning to try to digest the meaning and significance
> > of "multimethods" - for which there are Python modules.
>
> I found one at http://www.sff.net/people/neelk/open-source/Multimethod.py.
> Is that the same one you are talking about?
>

And one at:
http://bent-arrow.com/python

which I'm thinking is more recent and under more active development -
but I'm not sure.

> Multimethods appear to be exactly what you are asking for. But I'm not
sure
> they are the right thing to be asking for, if you know what I mean. :-)
>
> Let's look at your example of an Intersection constructor and the
variations
> you want to support:
>
>     Intersection(plane,line)
>     Intersection(line,plane)
>     Intersection(line,line)
>
> What I'd ask is why do you need to know the types of the two parameters?
>At what point does it matter? What method(s) of Intersection need to
function
> differently in each of the three cases?

> I think we need to see more code to figure out whether this can't be
> handled  without too much regard for object types. And even if some type
checking
> needed to take place, multimethods seem like overkill to me.

Well, I am senstive to taking the discussion too far off topic to edu-sig -
though I do have every intention of doing my best to pick your brain
off list.

Art