On 28 April 2011 22:31, mark florisson <markflorisso...@gmail.com> wrote: > On 28 April 2011 22:12, Robert Bradshaw <rober...@math.washington.edu> wrote: >> On Thu, Apr 28, 2011 at 12:48 PM, mark florisson >> <markflorisso...@gmail.com> wrote: >> >>> So I fixed all that, but I'm currently wondering about the proposed >>> cython.typeof(). I believe it currently returns a string with the type >>> name, and not the type itself. >> >> Yes. This is just because there's not really anything better to return >> at this point. We should "fix" this at some point in the future. >> >>> So I think it would be inconsistent to >>> suddenly start allowing comparison with 'is' and 'isinstance' and >>> such. >> >> I'm open to other suggestions, but would like an expression that >> resolves at compile time to true/false (and we need to do branch >> pruning on it). Note that type() is not good enough, because it has >> different semantics, i.e. >> >> cdef object o = [] >> typeof(o), type(o) >> >> so lets not touch that one. > > Right, so for fused types I don't mind string comparison with > cython.typeof(), but retrieval of the actual type for casts and > declaration remains open. I'd be fine with something like > cython.gettype().
It seems that this isn't optimized yet, but it looks to me like it wouldn't be very hard to do so. At least == and != could be resolved at compile time if the other operand is a string literal. > On the other hand, the user could already do this thing by manually > declaring another fused type that would perhaps be resolved based on > its usage. e.g. for my original example: > > ctypedef char *string_t > ctypedef cython.fused_type(int, string_t) attrib_t > > cdef func(struct_t mystruct, int i): > cdef attrib_t var = mystruct.attrib + i > > Is this something that should be supported anyway? Currently fused > types can only be used when appearing as argument types (in the > function body and as return value). > >>> I'm also wondering if it would be useful to allow actual type >>> retrieval, which could be used in declarations and casts. For instance >>> consider fusing two structs with the same attribute name but different >>> attribute types. Perhaps in your code you want to introduce a variable >>> compatible with such a type, e.g. consider this: >>> >>> ctypdef struct A: >>> int attrib >>> >>> ctypedef struct B: >>> char *attrib >>> >>> ctypedef cython.fused_type(A, B) struct_t >>> >>> cdef func(struct_t mystruct, int i): >>> cdef cython.gettype(mystruct.attrib) var = mystruct.attrib + i >>> ... >>> >>> What do you think? >> >> Yes, I was thinking that would be supported as well. >> >> - Robert >> _______________________________________________ >> cython-devel mailing list >> cython-devel@python.org >> http://mail.python.org/mailman/listinfo/cython-devel >> > _______________________________________________ cython-devel mailing list cython-devel@python.org http://mail.python.org/mailman/listinfo/cython-devel
