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From: "Prasad, Ramit" <ramit.prasad@jpmorgan.com.dmarc.invalid>
To: "rui.maciel@gmail.com" <rui.maciel@gmail.com>, "python-list@python.org" <python-list@python.org>
Subject: RE: Newbie: static typing?
Thread-Topic: Newbie: static typing?
Thread-Index: AQHOko+k2wcq/oXgRkS+Ng4sj/OLBJmLhTIA
Date: Thu, 8 Aug 2013 16:46:03 +0000
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Rui Maciel wrote:
> Chris Angelico wrote:
> 
> > On Tue, Aug 6, 2013 at 10:01 AM, Rui Maciel <rui.maciel@gmail.com> wrote=
:
> >> It would be nice if some functions threw an error if they were passed a
> >> type
> >> they don't support or weren't designed to handle.  That would avoid
> >> having to deal with some bugs which otherwise would never happen.
> >>
> >> To avoid this sort of error, I've been testing arguments passed to some
> >> functions based on their type, and raising TypeError when necessariy, b=
ut
> >> surely there must be a better, more pythonic way to handle this issue.
> >
> > def add_three_values(x,y,z):
> >     return x+y+z
> >
> > Do you want to test these values for compatibility? Remember, you
> > could take a mixture of types, as most of the numeric types can safely
> > be added. You can also add strings, or lists, but you can't mix them.
> > And look! It already raises TypeError if it's given something
> > unsuitable:
> 
> If the type problems aren't caught right away when the invalid types are
> passed to a function then the problem may only manifest itself in some far
> away point in the code, making this bug needlessly harder to spot and fix,
> and making the whole ordeal needlessly too time consuming.
> 
> 
> Rui Maciel

This can be true, but in personal experience does not happen 
often. I will say that dynamic typing ends up usually
being more future proof as I can later create a similar object
(but not in the same inheritance hierarchy) that will work
with older functions because the functions don't look for
certain types but rather just rely on duck typing.

I find this especially useful when testing or mocking. I can
create a test object and attach methods/attributes to the
test object to duck type as I desire to test the my desired code. 

I think the following reads are very interesting
for people new to Python from other languages (not just Java).
http://dirtsimple.org/2004/12/python-is-not-java.html
(and the flip side) http://dirtsimple.org/2004/12/java-is-not-python-either.=
html


~Ramit



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