On Thu, Jun 2, 2011 at 2:42 PM, mark florisson <markflorisso...@gmail.com> wrote: > On 2 June 2011 23:31, Robert Bradshaw <rober...@math.washington.edu> wrote: >> On Thu, Jun 2, 2011 at 2:18 PM, Dag Sverre Seljebotn >> <d.s.seljeb...@astro.uio.no> wrote: >>> On 06/02/2011 06:39 PM, Robert Bradshaw wrote: >>>> >>>> In looking at merging fused types, it's time to nail down the syntax. >>>> The current implementation is >>>> >>>> ctypedef cython.fused_type(list, dict, object) fused_t >>>> >>>> This requires an addition to the grammer to allow the "call" syntax in >>>> a type declaration, as well as special casing to make it allowed only >>>> in a typedef. What about >>>> >>>> cython.fused_type[list, dict, object]. >>>> >>>> One advantage is that indexing is already valid in type declarations, >>>> and its the typical syntax for parameterized types. Thoughts? Any >>>> other ideas? >>> >>> I don't really like overloading [] even more, and I think () (or, perhaps, >>> 'fused_type([list, dict, object])'). >>> >>> But I don't feel very strongly about it. >>> >>> If you only want this allowed in typedefs, then, being puristic, I think >>> that really a "fused type" is really different from a ctypedef, and that it >>> would warrant something like a new keyword. >>> >>> cdef fusedtype [list, dict, object] fused_t >>> >>> That's rather horrible, but you get the gist. The thing is, once you use a >>> ctypeudef, you really should allow >>> >>> def f(fused_type(float, double) x, fused_type(float, double) y): ... >>> >>> but then, how many fused types do you have, one or two? >> >> Two, and you can't refer to them. Such anonymous types could be handy >> for one-off functions, e.g. >> >> def f(fused_type[list, dict, object] x): ... >> >> but maybe that's not needed. >> >>> So this makes it seem to me that using ctypedef is a rather horrible hack. >> >> Yeah, this is the crux of the issue. (To be clear, Mark's >> implementation is good, it's our syntax that's hacky). It's perhaps >> less ugly than >> introducing a new keyword. A crazy idea: >> >> cdef fused floating_t: >> float >> double >> long double >> >> (in analogy with how we declare types like structs and enums). > > I like that syntax, the bad thing about ctypedef for me is that > everything goes on one line, at which point you have to start breaking > them if they get too long (which can happen quite easily with lenghty > names like 'long double complex'), which looks awkward. > > So much for trying to reduce grammar changes, though :)
Well, it introduces a new kind of node, rather than the kind of funny interaction/restriction with typedef, which got me thinking about this in the first place. Of course then you can't create an anonymous one for use in a function (which may be viewed as a feature or a defect). - Robert _______________________________________________ cython-devel mailing list cython-devel@python.org http://mail.python.org/mailman/listinfo/cython-devel
