On 10 May 2012 08:27, Vitja Makarov <vitja.maka...@gmail.com> wrote:
> 2012/5/10 Stefan Behnel <stefan...@behnel.de>:
>> Vitja Makarov, 08.05.2012 15:47:
>>> 2012/5/8 Stefan Behnel:
>>>> Vitja has rebased the type inference on the control flow, so I wonder if
>>>> this will enable us to properly infer this:
>>>>
>>>> def partial_validity():
>>>> """
>>>> >>> partial_validity()
>>>> ('Python object', 'double', 'str object')
>>>> """
>>>> a = 1.0
>>>> b = a + 2 # definitely double
>>>> a = 'test'
>>>> c = a + 'toast' # definitely str
>>>> return typeof(a), typeof(b), typeof(c)
>>>>
>>>> I think, what is mainly needed for this is that a NameNode with an
>>>> undeclared type should not report its own entry as dependency but that of
>>>> its own cf_assignments. Would this work?
>>>>
>>>> (Haven't got the time to try it out right now, so I'm dumping it here.)
>>>
>>> Yeah, that might work. The other way to go is to split entries:
>>>
>>> def partial_validity():
>>> """
>>> >>> partial_validity()
>>> ('str object', 'double', 'str object')
>>> """
>>> a_1 = 1.0
>>> b = a_1 + 2 # definitely double
>>> a_2 = 'test'
>>> c = a_2 + 'toast' # definitely str
>>> return typeof(a_2), typeof(b), typeof(c)
>>>
>>> And this should work better because it allows to infer a_1 as a double
>>> and a_2 as a string.
>>
>> How would type checks fit into this? Stupid example:
>>
>> def test(x):
>> if isinstance(x, MyExtType):
>> x.call_c_method() # type known, no None check needed
>> else:
>> x.call_py_method() # type unknown, may be None
>>
>> Would it work to consider a type checking branch an assignment to a new
>> (and differently typed) entry?
>>
>
> No, at least without special handler for this case.
> Anyway that's not that hard to implement isinstance() condition may
> mark x as being assigned to MyExtType, e.g.:
>
> if isinstance(x, MyExtType):
> x = <MyExtType> x # Fake assignment
> x.call_c_method()
>
That would be nice. It might also be useful to do branch pruning
before that stage, which may avoid a merge after the branch leading to
a different (unknown, i.e. object) type. That could be useful in the
face of fused types, where people write generic code triggering only a
certain branch depending on the specialization. Bit of a special case
maybe :)
>
>
>
> --
> vitja.
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