int/long unification hides bugs

Alex Martelli aleaxit at yahoo.com
Wed Oct 27 09:02:01 CEST 2004


kartik <kartick_vaddadi at yahoo.com> wrote:
   ...
> > Try doing some accounting in Turkish liras, one of these days.  Today,
   ...
> > [...]Even just for accounting, unlimited-size integers are simply much
> > more practical.

I see you quote this but can't refute it...

> > > as another example, using too long a string as an index into a
> > > dictionary is not a problem (true, the dictionary may not have a
> > > mapping, but i have the same issue with a short string). but too long
> > > an index into a list rewards me with an exception.
> > 
> > But the same index, used as a dictionary key, works just fine.  Specious
> > argument, therefore.
> 
> I don't think so. I didn't say that large numbers always cause
> trouble, so you can't claim to have refuted by argument by giving a
> single counter-example.

I rewrote your post, using long strings instead of large numbers, to
show the arguments are exactly identical, and equally bereft of
substance, against getting either unlimited strings or numbers as the
default.  You tried to show asymmetry by comparing strings used as keys
into a dictionary vs ints used as indices into a list, and I refute that
silly attempt: if you have dictionaries you can use long strings or
large numbers as keys into them just as well.

Your mention of lists, in fact, shows exactly how specious your
arguments for a default integer limit of 2**31-1 are.  That totally
arbitrary limit has nothing to do with the size of any given list; the
size of number that would give problems when used as list index varies,
but it's more likely to be a few millions, than billions.  _Moreover_,
as soon as you try to use a too-large index for the specific list, you
get an IndexError.  It's therefore totally useless to try and get an
OverflowError instead if the index, besides being too big for that
specific list, is also over 2**31-1 (or other arbitrary boundary).


> > As common and everyday a
> > computation (in some fields) as the factorial of 1000 (number of
> > permutations of 1000 objects) is 2**8530 -- and combinatorial arithmetic
> > is anything but an "ivory tower" pursuit these days, and factorial is
> > the simplest building block in combinatorial arithmetic.
> 
> It's nice to get some facts, rather than an attempt to prove your
> position by analogy between ints & strings ("Proof by analogy is
> fraud" - Bjarne Stroustrup)

Go use C++, then, and stop wasting our time.  If we preferred the way
Stroustrup designs programming languages, to that in which van Rossum
designs them, we'd be over in comp.lang.c++, not here in
comp.lang.python -- ever thought of that?

The analogy I posed, and still defend, merely shows your arguments were
badly thought out, weak, and totally useless in the first place.  It
does not need to 'prove' anything, because we're neither in a court of
law, nor in mathematics: it just shows up your arguments for the
worthless froth they are.  The facts (that should be obvious to anybody,
of course) that the factorial function easily makes very big numbers,
that some countries have very devalued currencies, etc, further show
that big numbers (just like big strings) _are_ useful to practical
problems, thus your totally wrong-headed request to put default limits
on numbers would also cause practical damage -- for example, it would
make an accounting-arithmetic package designed with strong currencies in
mind (Euros, dollars, pounds, ...) unusable for weak currencies, because
of the _default_ nature of the limits.

Fortunately there is no chance whatsoever that Python will get into
reverse gear and put back the arbitrary default limits you hanker for.
If the many analogies, arguments, and practical examples that have been
offered to help you see why, help you accept the fact, good.  If not,
good riddance -- you have not offered _one_ sound and useful line of
reasoning throughout this big thread, after all, so it's not as if
losing your input will sadly impoverish discussions here.


Alex



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