On Mon, Aug 29, 2011 at 10:57 PM, Vitja Makarov <vitja.maka...@gmail.com> wrote:
> 2011/8/30 Robert Bradshaw <rober...@math.washington.edu>:
>> On Sun, Aug 28, 2011 at 4:00 AM, Vitja Makarov <vitja.maka...@gmail.com>
>> wrote:
>>> 2011/8/27 Vitja Makarov <vitja.maka...@gmail.com>:
>>>> 2011/8/27 Vitja Makarov <vitja.maka...@gmail.com>:
>>>>> 2011/8/26 Vitja Makarov <vitja.maka...@gmail.com>:
>>>>>> 2011/8/25 Vitja Makarov <vitja.maka...@gmail.com>:
>>>>>>> 2011/8/25 Vitja Makarov <vitja.maka...@gmail.com>:
>>>>>>>> 2011/8/25 Stefan Behnel <stefan...@behnel.de>:
>>>>>>>>> Vitja Makarov, 25.08.2011 20:32:
>>>>>>>>>>
>>>>>>>>>> 2011/8/25 Stefan Behnel<stefan...@behnel.de>:
>>>>>>>>>>>
>>>>>>>>>>> Vitja Makarov, 25.08.2011 18:11:
>>>>>>>>>>>>
>>>>>>>>>>>> 2011/8/24 Stefan Behnel:
>>>>>>>>>>>>>
>>>>>>>>>>>>> Vitja Makarov, 24.08.2011 21:17:
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> I tried final classes:
>>>>>>>>>>>>>> 2. In this example foo call is done through virtual table
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> cimport cython
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> @cython.final
>>>>>>>>>>>>>> cdef class Foo:
>>>>>>>>>>>>>> cdef foo(self):
>>>>>>>>>>>>>> print 'haha'
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> def test():
>>>>>>>>>>>>>> cdef Foo a = Foo()
>>>>>>>>>>>>>> a.foo()
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> __pyx_t_1 = ((struct __pyx_vtabstruct_3yyy_Foo
>>>>>>>>>>>>>> *)__pyx_v_a->__pyx_vtab)->foo(__pyx_v_a); if
>>>>>>>>>>>>>> (unlikely(!__pyx_t_1))
>>>>>>>>>>>>>> {__pyx_filename = __pyx_f[0]; __pyx_lineno = 12; __pyx_clineno =
>>>>>>>>>>>>>> __LINE__; goto __pyx_L1_error;}
>>>>>>>>>>>>>
>>>>>>>>>>>>> Right, this is not implemented yet. Feel free to do so. Also see
>>>>>>>>>>>>>
>>>>>>>>>>>>> http://trac.cython.org/cython_trac/ticket/474
>>>>>>>>>>>>>
>>>>>>>>>>>>>
>>>>>>>>>>>>>> 3. I can't use final decorator for methods (error reported)
>>>>>>>>>>>>>
>>>>>>>>>>>>> http://trac.cython.org/cython_trac/ticket/586
>>>>>>>>>>>>
>>>>>>>>>>>> What is the prefered syntax keyword inline or final decorator?
>>>>>>>>>>>
>>>>>>>>>>> "final" is the right option here.
>>>>>>>>>>>
>>>>>>>>>>> They are orthogonal concepts. Only because you declare a method
>>>>>>>>>>> "final"
>>>>>>>>>>> does
>>>>>>>>>>> not mean you want to inline it, and just because you declare it
>>>>>>>>>>> "inline"
>>>>>>>>>>> does not (necessarily) mean that you cannot override it.
>>>>>>>>>>> Admittedly, the
>>>>>>>>>>> semantics of an overridable inline method may turn out to be
>>>>>>>>>>> somewhat
>>>>>>>>>>> obscure and error prone, so I think it's a good idea to let "inline"
>>>>>>>>>>> imply
>>>>>>>>>>> "final". But not the other way round.
>>>>>>>>>>
>>>>>>>>>> But both inline and final methods should bypass vtab, right?
>>>>>>>>>
>>>>>>>>> Yes. But in the "final" case, it's always clear which method
>>>>>>>>> implementation
>>>>>>>>> to use - it's not overridable, so there is only one choice. In the
>>>>>>>>> "inline"
>>>>>>>>> case, it could still be overridable and we may have a subtype of the
>>>>>>>>> declared type in our hands at runtime, thus choosing the wrong method
>>>>>>>>> at
>>>>>>>>> compile time. That's why only the "final" case is safe.
>>>>>>>>>
>>>>>>>>> Note that I'm only talking about the semantics of the qualifier
>>>>>>>>> themselves
>>>>>>>>> here. If we allow "inline" methods, I think we should force them to be
>>>>>>>>> "final" as well. But that's a practical choice, not a semantic
>>>>>>>>> implication.
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>> Also I'm not sure about C inline qualifier here.
>>>>>>>>>
>>>>>>>>> That's what "inline" requests.
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>> I see three options:
>>>>>>>>>>
>>>>>>>>>> - non-virtual: bypass vtab
>>>>>>>>>> - final: non-virtual, non-overridable
>>>>>>>>>
>>>>>>>>> How would you want to bypass the vtable in the "non-virtual" case if
>>>>>>>>> the
>>>>>>>>> method is overridable?
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>> - inline: non-virtual, C inline qualifier is used
>>>>>>>>>
>>>>>>>>> Correct.
>>>>>>>>>
>>>>>>>>
>>>>>>>> Ok.
>>>>>>>>
>>>>>>>> I think it's better to implement final method then user could choose
>>>>>>>> to use inline qualifier or not.
>>>>>>>>
>>>>>>>
>>>>>>> I tried it here:
>>>>>>> https://github.com/vitek/cython/commit/ddf80a80dc75aced2cd92dc32afa77a7bcf2de02
>>>>>>>
>>>>>>> There is one problem: vtab bypassing should be enabled if final method
>>>>>>> is defined in the same module.
>>>>>>> I don't know how to check that final method comes from cimport (it's
>>>>>>> okay with pxd, the problem is pyx)
>>>>>>>
>>>>>>
>>>>>>
>>>>>> https://github.com/vitek/cython/commit/6e91fc257a683018ba6be340d384f9a7c34ef425
>>>>>>
>>>>>> Here is update version. I've add tree asserts and final method's
>>>>>> prototypes.
>>>>>>
>>>>>> --
>>>>>> vitja.
>>>>>>
>>>>>
>>>>> I've created ticket for compiler crash when cython.final is used
>>>>> inside pxd file:
>>>>>
>>>>> http://trac.cython.org/cython_trac/ticket/722
>>>>>
>>>>> Also I've updated final methods test case (added tree path assertions)
>>>>> https://github.com/vitek/cython/commit/92edb09419c9b77a792f7c43e6ddd760b00c4e74
>>>>>
>>>>>
>>>>> About declaration origin detection may be it's a good idea to have a
>>>>> flag at scope level something like is_pxd_scope or
>>>>> is_declaration_scope?
>>>>>
>>>>
>>>> It seems to me that I found a way to fix pxd/pyx cimport problem. I've
>>>> created pull request:
>>>>
>>>> https://github.com/cython/cython/pull/59
>>>>
>>>
>>> I've add support for inline methods, now you can declare inline method
>>> in pxd file:
>>>
>>> cdef class Foo:
>>> cdef inline foo(self):
>>> return 1
>>
>> Cool.
>>
>> I suppose for cross-module calls, non-inline methods vtables are best
>> one can do short of actually linking the modules together.
>
> Sure. This is how it works now. But noitice that final isn't supported
> now at pxd scope. So it might not work.
>
>
> https://github.com/cython/cython/pull/59/files#L5R1888
>
> For subclassing I check that both 3parent and children are in the same scope.
> When pxd is cimported vtable bypassing should be disabled in case it's
> cimported from anpther module.
> Not sure how to implement this. I think we should first fix final at pxd.
>
>> One
>> question about your code--I'm not seeing how you're disallowing
>> overriding final cpdef methods from Python. (Should we even allow
>> final cpdef methods on non-final classes?)
>>
>
> I think it's hard and tricky to disallow cpdef overriding but I think
> it's better to have cpdef final methods.
> And I wouldn't argue if you say that final cpdef methods shouldn't be
> allowed at all.
Yes, disallowing it with an explicit compile-time error was what I was
thinking.
- Robert
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