[Python-Dev] "result type only depends on operand types"...?

[Aahz]

On Sun, Mar 31, 2002, Alex Martelli wrote:
>
> Back on March 10 in the thread on PEP 285 Guido wrote:
> 
> """
> This is a very general rule that I like a lot: that the type of a
> result should only depend on the type of the arguments, not on their
> values.  I expect that this rule will make reasoning about programs
> (as in PsyCo or PyChecker) easier to do.
> """
> 
> And yet...:
> 
> >>> type(2**10)
> <type 'int'>
> >>> type(2**100)
> <type 'long'>
> 
> ...doesn't this apply to many operators on ints in 2.2?  Yet _another_
> (set of) exception(s) with practicality beating purity?  Perhaps, but if a 
> "very general rule" has so many exceptions in frequent and fundamental
> cases, is it a rule at all...?

Channeling Guido: this isn't an "exception", this is a phased step in
the progress toward unifying ints and longs.  Eventually, the
distinction will go away except for explicitly declared platform ints,
and an overflow error on a platform int will once again raise an
exception rather than transforming automatically.
-- 
Aahz (aahz@pythoncraft.com)           <*>         http://www.pythoncraft.com/

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