> On 07 Apr 2016, at 14:15, Damien Pollet <damien.pollet+ph...@gmail.com> wrote:
>
> I think in that case you need to pass an instance of FFIExternalValueHolder.
yes.
you can take the test FFIExternalValueHolderTests>>testCall as an example.
But since it uses anonymous classes it might require a better explanation,
there is the class comment, but basically, you do this:
1) Declare a class variable
MyClass class>>initialize
INT_PTR := FFIExternalValueHolder ofType: ‘int’.
2) Replace "int *” in your function calls with your new type:
glGetAttribute: attr into: value
^ self ffiCall: #( int SDL_GL_GetAttribute(SDL_GLattr attr, INT_PTR
value) )
3) pass an instance of INT_PTR to get the value:
| ptr value |
ptr := INT_PTR new.
self glGetAttribute: anAttributeIDontKnow into: ptr.
value := ptr value.
Esteban
>
> On 7 April 2016 at 17:42, Thibault Raffaillac <thibault.raffail...@inria.fr
> <mailto:thibault.raffail...@inria.fr>> wrote:
> Hi again,
>
> Does anyone know what is the state of return by reference in FFI?
> Example:
> glGetAttribute: attr into: value
> <primitive: #primitiveNativeCall module: #NativeBoostPlugin error:
> errorCode>
> ^ self nbCall: #( int SDL_GL_GetAttribute(SDL_GLattr attr, int
> *value) )
>
> On my image (50666) it does nothing on value yet (if nil, remains nil, if
> SmallInteger 0, remains 0).
> (SDL2 glGetAttribute: 6 into: value) should return 16.
> I've seen NBOpenGL put "out" before value in method header, should it matter?
> (does not make it work though)
> Last but not least, should we attach '*' to the type or variable for FFI to
> understand it is a pointer?
>
> Cheers,
> Thibault Raffaillac
>
>
