Le dimanche 05 juin 2011 à 06:13 -0700, Vinzent Steinberg a écrit :
> On 4 Jun., 18:24, Ronan Lamy <ronan.l...@gmail.com> wrote:
> > No, it shouldn't, because ZZ isn't a set. That's indeed the problem with
> > using the name of an abstract mathematical set to designate a concrete
> > type.
>
> If I understand it correctly, ZZ is the implementation of the ring of
> integers, so mathematically it is nothing but a set with some special
> elements and a few mappings, satisfying some axioms. For convenience,
> you refer to the set only, even if you mean the ring. So I think the
> implementation is fine.
>
Your understanding seems to contradict Aaron's. ZZ can't be
simultaneously a proxy for a concrete type and a representation of an an
abstract mathematical concept.
> > "Symbol('n', integer=True) in ZZ" looks like something that should
> > obviously be True, but actually it doesn't make sense.
>
> Well, in polys this would be rather ZZ[n], because ZZ means concrete
> integers and not symbolic ones.
But we need symbolic integers if we want to do any symbolic manipulation
on integers. In the main core, there's .is_integer and .is_Integer, they
are different and we need both. Why change the rules in the polynomial
core?
> > So 'isinstance(a,
> > int_type)' isn't just more readable, it also prevents dangerous
> > misunderstandings.
>
> > BTW, ZZ.__contains__ does exist and does something different from
> > ZZ.of_type.
>
> The difference is subtle, ZZ.__contains__ tries to convert the type,
> but ZZ.of_type only checks the type. It is like '==' vs. 'is'.
>
> Vinzent
>
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