ExternalCallback in StructureField

> Hello.
> I have an ExternalStructure containing a function pointer:
>
> MyStruct class>>defineFields
>
> self
>    defineField: #field1 type: (PointerField type: String);
>    defineField: #field2 type: LPVOIDField new
>
> now I want to fill the second field with an ExternalCallback, how should I
> do it ?
>
> Thanks in advance
>
>

> > Hello.
> > I have an ExternalStructure containing a function pointer:
> >
> > MyStruct class>>defineFields
> >
> > self
> >    defineField: #field1 type: (PointerField type: String);
> >    defineField: #field2 type: LPVOIDField new
> >
> > now I want to fill the second field with an ExternalCallback, how should

> > do it ?
> >
> > Thanks in advance
> >
> >
>
> Add an instance variable to the structure - the iv is necessary to prevent
> the callback object from being garbage collected while it is still
> referenced from the structure. Then define an accessor such as:
>
> callback: anExternalCallback
>     callback := anExternalCallback.
>     self field2: anExternalCallback asParameter yourAddress
>
> Regards
>
> Blair
>
>
>