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List:       python-bugs-list
Subject:    [issue15224] Range: Additional Methods (min/max/__and__)
From:       Mark Dickinson <report () bugs ! python ! org>
Date:       2012-06-30 18:27:58
Message-ID: 1341080878.66.0.547904831323.issue15224 () psf ! upfronthosting ! co ! za
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Mark Dickinson <dickinsm@gmail.com> added the comment:

Okay, I'm closing this as rejected.  Some responses:

> I don't think that complexity or specialisation should matter.

Well, Python's supposed to be a general-purpose language;  range objects *are* \
generally useful for all sorts of tasks, but it's far from clear that being able to \
intersect them would be valuable to a wide range of people.

> Conceptually, why not bring range to its full potential using facilities that \
> python already provides.

Because additions to the language (especially the core language, as opposed to the \
standard library) are far from free.  First the feature needs to be implemented, \
reviewed, fully tested and documented.  Then it needs to be maintained.  Other Python \
implementations (PyPy, IronPython, Jython, etc.) need to create their own \
implementations.  Text book writers need to keep up with the changes.  The addition \
makes the language larger,  making more to learn for students of the language and \
more to teach for teachers.  In this particular case, I'm worried that there's a real \
risk of making a poor API choice that will inhibit later language expansion---you \
can't just add a method to a builtin type without considering the impact on the \
language as a whole, both now and in the future.

So there's a significant cost in each core language addition, even for something as \
simple-looking as this.  And the benefits of the addition have to be weighed against \
that cost.  In this case, I see very little benefit---I doubt that there's a real and \
common need for range intersections.

And all of the above is before discussing the implementation difficulties associated \
with this particular feature:  it would likely require a C implementation of the gcd \
function, which is *not* a trivial thing to do efficiently, so we're looking at much \
more than just a few lines of code, with all the attendant risks of introducing new \
bugs.

----------
resolution:  -> rejected
status: open -> closed

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