Iâm not happy with the method name, but I think is well explained in method comments: ExternalAddress>>rollToArity: arity "This will 'roll' a pointer to a certain arity. What does this means? Let's say I have a method who will be called with a ** arity: method: aPointer self ffiCall: #( method ( MyExternalObjectClass **aPointer) ) This usually means that method will put a pointer in the address of aPointer. And what I actually want is this pointer. So I do Something like this: p := MyExternalObjectClass new. self mehod: p. And I expect to have 'p' correctly initialised on return. Well... tha's not so simple :) When compiling #method:, UnifiedFFI needs to first 'roll' the pointer (which means to take a pointer of a pointer of a pointer... as many pointers as arity solicited), and then, after call, it needs to 'unroll' all this pointers (see #unrollFromArity: method) â ByteArray>>rollToArity: arity "This is complicated... I assuming this ways of calling a function: arity == 1: ----------- ByteArray works as pointer buffer of single pointer to something: ex 1) buffer := ByteArray new: 4. self ffiCall: #( void function (int *buffer) ). ex 2) buffer := 'Hello, World' asByteArray. self ffiCall: #( void function (char *buffer) ). arity > 1: ---------- ByteArray works as pointer to allocate results: ex 1) pointer := ByteArray new: (FFIExternalType pointerSize). self ffiCall: #( void function ( char **answer )). In this case this will not work fine because content of ByteArray needs to be a pointer too, and then it needs to be allocated in the heap... while this could be managed, I'm puting for the moment just an error and a recommendation of using an ExternalAddress. " basically, is the equivalent of â&â operator in C. you can manually do the same by doing: | var | var := 42 pointer. who will give you a byte array with signedLongAt: 1 == 42. ⦠but since old NB was doing this implicitly, we need to provide it too :) Esteban ps: Why do you need to know it? This is internal in UnifiedFFI so nobody should need to deal with it.
On 17 Feb 2016, at 16:43, Alexandre Bergel <alexandre.bergel@me.com> wrote:
Esteban,
What Object>>rollToArity: is supposed to do? It belongs to UnifiedFFI
Cheers, Alexandre -- _,.;:~^~:;._,.;:~^~:;._,.;:~^~:;._,.;:~^~:;._,.;: Alexandre Bergel http://www.bergel.eu ^~:;._,.;:~^~:;._,.;:~^~:;._,.;:~^~:;._,.;:~^~:;.