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.
Stefan
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