On Sun, May 22, 2016 at 4:09 PM, Michael Lindon
<michael.s.lin...@gmail.com> wrote:
> I have function baz which outputs the product of the input at 2:
>
> function baz{T}(x::T)
> return convert(Cdouble,x*2)::Cdouble
> end
>
> I want to use this function in some C function that I am calling. Running
>
> julia> myptr=cfunction(baz,Cdouble,(Ref{Cdouble}))
> Ptr{Void} @0x00007f2623c9c1d0
>
> is fine, and I can proceed to pass the function pointer to my C function.
>
>
>
>
> Say I want the product of the input and another integer. I have a higher
> order function bar
>
> function bar(y)
> function foo{T}(x::T)
> return convert(Cdouble,x*y)::Cdouble
> end
> end
>
> now I can get the baz function like this
>
> julia> foo=bar(2)
> foo (generic function with 1 method)
>
> foo has the same method as baz, and the same functionality, but cfunction
> results in an error:
>
> julia> myptr=cfunction(foo,Cdouble,(Ref{Cdouble}))
> ERROR: cfunction: no method exactly matched the required type signature
> (function not yet c-callable)
> in cfunction at c.jl:9
>
>
> :(
>
>
> How can I pass the function pointers of the outputs of my higher order
> function bar to my C function?
Closure is not supported right now. You need to pass the data
explicitly. (Most C API should allow that by allowing you to pass an
arbitrary `void*` in additional to the function pointer)
>
