2011/8/30 Robert Bradshaw <[email protected]>:
> On Tue, Aug 30, 2011 at 9:14 AM, Vitja Makarov <[email protected]>
> wrote:
>> 2011/8/30 Robert Bradshaw <[email protected]>:
>>> On Mon, Aug 29, 2011 at 10:57 PM, Vitja Makarov <[email protected]>
>>> wrote:
>>>> 2011/8/30 Robert Bradshaw <[email protected]>:
>>>>> On Sun, Aug 28, 2011 at 4:00 AM, Vitja Makarov <[email protected]>
>>>>> wrote:
>>>>>> 2011/8/27 Vitja Makarov <[email protected]>:
>>>>>>> 2011/8/27 Vitja Makarov <[email protected]>:
>>>>>>>> 2011/8/26 Vitja Makarov <[email protected]>:
>>>>>>>>> 2011/8/25 Vitja Makarov <[email protected]>:
>>>>>>>>>> 2011/8/25 Vitja Makarov <[email protected]>:
>>>>>>>>>>> 2011/8/25 Stefan Behnel <[email protected]>:
>>>>>>>>>>>> Vitja Makarov, 25.08.2011 20:32:
>>>>>>>>>>>>>
>>>>>>>>>>>>> 2011/8/25 Stefan Behnel<[email protected]>:
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> 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.
>>>
>>
>> What about final classes with cpdef methods?
>>
>> @cython.final
>> class Foo:
>> cpdef bar(self):
>> pass
>>
>> Should that raise an error?
>
> That should be perfectly fine.
>
I'm not sure here. This would make users write code like this:
@final
cdef class Foo:
cdef _is_foo(self):
return self._foo
def is_foo(self):
return self._is_foo()
cpdef is more convinient here. Also note that final class couldn't
subclass types with cpdef methods.
--
vitja.
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