[Python-ideas] Fast sum() for non-numbers - why so much worries?

[David Mertz]

I think I've followed every post in this long thread and the spinoffs.  I
don't want to try to address all the small points and sub-threads. Here's
my overall take-away:

* Using 'sum()' to concatenate sequences or iterators is unintuitive,
inferior to other existing techniques, and any code that does so is already
*slightly* "broken." (stylistically, not functionally necessarily).

Given my perception in the above bullet, I would be +1 on deprecating this
use altogether (i.e. raise DeprecationWarning if a good way could be found
to distinguist "sequence" from "some other thing that implements .__add__()
and is numerical enough").  Even if there's no practical way to make that
distinction in a duck-typed language, the documentation should (continue
to) say "sum() is the wrong way to concatenate sequences".  I am -1 on
modifying the semantics of sum() to use .__iadd__().

Even though we have TOOWTDI, in reality there are lots of Python constructs
that one *can* do, but really just *shouldn't*.  Using sum() on sequences
feels about like ._getframe() hacks or slightly perverse generator
comprehensions on can write (e.g. for side-effects).  We're all adults, and
we're not going to stop you (unless we do so with DeprecationWarning), but
it's just not the *right* thing to do.

David...

-- 
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advocates of freedom in prisons.  Intellectual property is
to the 21st century what the slave trade was to the 16th.
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