2013/5/21 mark florisson <markflorisso...@gmail.com> > On 21 May 2013 14:41, Vitja Makarov <vitja.maka...@gmail.com> wrote: > > > > > > > > 2013/5/21 mark florisson <markflorisso...@gmail.com> > >> > >> On 21 May 2013 14:14, Vitja Makarov <vitja.maka...@gmail.com> wrote: > >> > > >> > > >> > > >> > 2013/5/21 mark florisson <markflorisso...@gmail.com> > >> >> > >> >> On 21 May 2013 11:26, Vitja Makarov <vitja.maka...@gmail.com> wrote: > >> >> > Hi! > >> >> > > >> >> > Recently I've started work on new type inference engine. Now it's > >> >> > almost > >> >> > ready and I want to discuss it. > >> >> > > >> >> > It works like this: first infer type for each assignment then for > >> >> > whole > >> >> > entry. It has some advantages over previous algorithm: > >> >> > - it handles assignment cycles, see test_swap() for example > >> >> > - it can infer type using info about assignments on the whole > entry: > >> >> > > >> >> > a = 1 > >> >> > b = a > >> >> > a = "str" > >> >> > > >> >> > a is python object and b is integer. > >> >> > > >> >> > Here are testcases that show some new cases it can solve: > >> >> > > >> >> > > >> >> > > https://github.com/vitek/cython/blob/_type_inference_new/tests/run/type_inference_new.pyx > >> >> > > >> >> > Here is branch for it > >> >> > https://github.com/vitek/cython/tree/_type_inference_new > >> >> > > >> >> > -- > >> >> > vitja. > >> >> > > >> >> > _______________________________________________ > >> >> > cython-devel mailing list > >> >> > cython-devel@python.org > >> >> > http://mail.python.org/mailman/listinfo/cython-devel > >> >> > > >> >> > >> >> Hey Vitja, > >> >> > >> >> Cool! How do you want to handle variable merge at control flow joins? > >> >> Would you promote (backwards incompatible), use a union type, or > >> >> object? E.g. what does this result in: > >> >> > >> >> x = 0 > >> >> for i in range(N): > >> >> x += 0.2 * i > >> >> print typeof(x) > >> > > >> > > >> > Hi Mark, > >> > > >> > Nothing changed in your example old algorithm was able to handle this > >> > "simple" kind of cycles as well as new one: > >> > > >> > def foo(int N): > >> > x = 0 > >> > for i in range(N): > >> > x += 0.2 * i > >> > print typeof(x) > >> > > >> > So this function (not that N is an integer here) will print 'dobule'. > >> > > >> > With new algorithm we can go further: > >> > > >> > def foo(int N): > >> > x = 1 > >> > y = 0 > >> > for i in range(N): > >> > x = x * 0.1 + y * 0.2 > >> > y = x * 0.3 + y * 0.4 > >> > print typeof(x), typeof(y) > >> > > >> > Here both x and y will be inferred as double > >> > > >> > >> Ok, so I assume it promotes the incoming types (all reaching > >> definitions)? If N == 0, then when using objects you get an int, > >> otherwise a double. What happens when the reaching types cannot be > >> promoted together? Do you fall back to object? > > > > > > Can you provide example please? And yes if type cannot be inferred it > > fallback to object. > > > > Sure, e.g. > > if cond: > x = 2 > else: > x = "hello" > use(x) > > x will be of object type here.
> A tricky one is this: > > try: > x = f() # let's say 'double' > x = g() # let's say 'string' > finally: > print typeof(x) # what does this print if 'f' can raise an > exception? > > As well as here. Can it raise exception or not doesn't matter here since typeof() returns type of entry and it's calculated at compile time. -- vitja.
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