Ned Batchelder wrote:
[...]
> Your original statement sounded like, "The else clause can
> never be executed,"
No. Of course not. Note that i mentioned _pragmatism_. My
complaint about the else-clause was not that it could
_never_ be executed, my complaint that was that the else-
clause (in Terry's example) serves no useful purpose save to
act as a semantical placeholder for a non-action. Heck, it
doesn't even log anything! "Practicality beats purity". For
instance:
(1) Would it be practical to make a shopping list that
includes only the products you _don't_ want to buy?
no ham
no eggs
no spam
no Limburger
"Okay, but what do we _need_!!!"
(2) How about a list of navigation directions that includes
tangential info?
"After you take the second left turn, you'll see a big
windmill -- just ignore that"
(3) How about a recipe that includes non-ingredients?
1 egg
2 pounds of ham
0 teaspoons coarse sea-salt
0 cups of finely shreded Limburger
...
> which would have been in direct opposition to the point,
> that slicing outside the limits would produce an empty
> list, not an exception.
And again, that is precisely why i raised an objection to
this else-clause. Because the inclusion of this else-clause
is a distraction from the point.
> I'm not sure why you are certain that there's never a
> reason to execute code in that case.
Oh, there will be a _reason_ for else-clause to execute
(when the slice overlaps the boundary), but i argue the code
contained within is not a _good_ reason for it to execute.
item = seq[n:n+1]
if item:
process(item)
else:
do_without_item()
"do_without_item()" implies a non-action. However, that's
not to say that under different circumstances, the else-
clause might serve a practical purpose for a programmer. For
instance, even a logging event serves a purpose.
ss, se = n, n+1
item = seq[ss:se]
if item:
process(item)
else:
print('Slice ({0}, {1}) out of bounds!'.format(ss, se))
> Perhaps I have a simulation on a conceptually infinite
> line, but only store the actual points needed. The "non
> action" would be to extend the line.
That logic does not follow! How do you _extend_ an infinite
line? :-). Of course, in the realm of maths, a line is by
definition infinite.
But whether you're speaking in metaphor or not, there are
literally infinite ways in which an else-clause can be
justified. My argument was simply: "do_without_item()" is
not a legitimate justification.
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