Yichao, try it on 0.5.0-dev+2422
julia> type SomeCallBack
z::Int
end
julia> (_::SomeCallBack)(c) = _.z + c
julia> s = SomeCallBack(24)
SomeCallBack(24)
julia> s(10)
34
On Sunday, January 31, 2016 at 4:01:09 PM UTC-5, Yichao Yu wrote:
>
> On Sun, Jan 31, 2016 at 1:10 PM, Christopher Alexander
> <[email protected] <javascript:>> wrote:
> > Yea, can someone explain the proper syntax here? What would be the case
> if
> > I wanted to build a callable type? What if I want to do something like
> > this?
> >
> > call{T <: MyAbstractType)(t::T, a::Int) = t.a + a
>
> If the parameter is not used otherwise you can simply do
>
> `(t::MyAbstractType)(a::Int) = t.a + a`
>
>
> Simply using a type parameter doesn't seem to work and that feels like
> a bug to me.
>
>
> >
> > Thanks!
> >
> > Chris
> >
> >
> > On Sunday, January 31, 2016 at 4:27:00 AM UTC-5, Bryan Rivera wrote:
> >>
> >> I just realized #13412 has been merged.
> >>
> >> What should this look like now that `Base.call(...)` is deprecated?
> >>
> >> Thinking something like:
> >>
> >> (_::SomeCallBack)(c) = _.z + c
> >>
> >>
> >> On Sunday, January 31, 2016 at 3:47:03 AM UTC-5, Bryan Rivera wrote:
> >>>
> >>> Cedric, I refactored the problem and this works well.
> >>>
> >>> What do you mean "I would favor using a regular function call with a
> >>> descriptive name"?
> >>>
> >>> I was thinking replace `Base.call` with a function name. But that
> does
> >>> not work if the function is in the top-level scope in another file.
> >>>
> >>> On Thursday, January 21, 2016 at 9:56:51 PM UTC-5, Cedric St-Jean
> wrote:
> >>>>
> >>>> Something like this?
> >>>>
> >>>> function function1(a, b, f) # Variable needed in callback fun
> injected.
> >>>> if(a > b)
> >>>> c = a + b
> >>>> res = f(c) # Callback function has been injected.
> >>>> return res + 1
> >>>> else
> >>>> # do anything
> >>>> # but return nothing
> >>>> end
> >>>> end
> >>>>
> >>>> type SomeCallBack
> >>>> z::Int
> >>>> end
> >>>> Base.call(callback::SomeCallBack, c) = c + callback.z
> >>>>
> >>>> function1(2, 1, SomeCallBack(10))
> >>>>
> >>>> Because of JIT, this is 100% equivalent to your "callback function
> has
> >>>> been injected" example, performance-wise. My feeling is that .call
> >>>> overloading is not to be abused in Julia, so I would favor using a
> regular
> >>>> function call with a descriptive name instead of call overloading,
> but the
> >>>> same performance guarantees apply. Does that answer your question?
> >>>>
> >>>> On Thursday, January 21, 2016 at 9:02:50 PM UTC-5, Bryan Rivera
> wrote:
> >>>>>
> >>>>> I think what I wrote above might be too complicated, as it is an
> >>>>> attempt to solve this problem.
> >>>>>
> >>>>> In essence this is what I want:
> >>>>>
> >>>>>
> >>>>>
> >>>>> function function1(a, b, onGreaterThanCallback)
> >>>>> if(a > b)
> >>>>> c = a + b
> >>>>> res = onGreaterThanCallback(c, z)
> >>>>> return res + 1
> >>>>> else
> >>>>> # do anything
> >>>>> # but return nothing
> >>>>> end
> >>>>> end
> >>>>>
> >>>>>
> >>>>> global onGreaterThanCallback = (c) -> c + z
> >>>>>
> >>>>> function1(a, b, onGreaterThanCallback)
> >>>>>
> >>>>>
> >>>>> Problems:
> >>>>>
> >>>>> The global variable.
> >>>>>
> >>>>> The anonymous function which has performance impact (vs other
> >>>>> approaches). We could use Tim Holy's @anon, but then the value of
> `z` is
> >>>>> fixed at function definition, which we don't always want.
> >>>>>
> >>>>> I think that the ideal optimization would look like this:
> >>>>>
> >>>>> function function1(a, b, z) # Variable needed in callback fun
> >>>>> injected.
> >>>>> if(a > b)
> >>>>> c = a + b
> >>>>> res = c + z # Callback function has been injected.
> >>>>> return res + 1
> >>>>> else
> >>>>> # do anything
> >>>>> # but return nothing
> >>>>> end
> >>>>> end
> >>>>>
> >>>>>
> >>>>> function1(a, b, z)
> >>>>>
> >>>>> In OO languages we would be using an abstract class or its
> equivalent.
> >>>>> But I've thought about it, and read the discussions on interfaces,
> and don't
> >>>>> see those solutions optimizing the code out like I did above.
> >>>>>
> >>>>> Any ideas?
>
