Following on from my "Parting words" at [1] I'd like to add the following...

but I'm seeking some expert feedback before logging an issue.

For discussion background, here is a reference C program that sets up the framework for a callback that returns an enumeration...

----------example.c

�� #include <stdio.h>

�� typedef enum {

�� �� A = 1,

�� �� B = 2,

�� �� C = 3

�� } CallBackReturnValue;

�� CallBackReturnValue callbackFn() {

�� �� return B;

�� }

�� CallBackReturnValue callout( CallBackReturnValue (*callback)() )

�� {

�� �� return callback();

�� }

�� int main()

�� {

�� �� printf("%d\n", callout(callbackFn) );

�� �� return 0;

�� }

$ gcc ��-Wall -Werror ��example.c

$ ./a.out��

$ gcc ��-c ��-Wall ��-Werror ��-fpic ��example.c

FFIExternalEnumeration subclass: #CallBackReturnValue

instanceVariableNames: ''

classVariableNames: ''

package: 'AAAExample'

CallBackReturnValue class >>��enumDecl

�� �� ^ #( A 1

�� �� �� B 2

�� �� ��C 3 )

CallBackReturnValue class >> initialize

self initializeEnumeration

FFILibrary subclass: #Example

instanceVariableNames: ''

classVariableNames: ''

package: 'AAAExample'

Example >>��unixModuleName

^ '/tmp/example.so'

Example class >>��callout: callbackBlock

^ self ffiCall: #( int callout ( FFICallback callbackBlock ) ) module: Example

Example class >> doCallback

| callbackFn |

callbackFn :=��

�� FFICallback

signature: ��#( CallBackReturnValue ( void ) )

block: [ B ].

^ Example callout: callbackFn.

callbackFn :=��

���� FFICallback

signature: ��#( CallBackReturnValue ( void ) )

block: [ B value ]. "<==="

�� FFIExternalEnumerationType >>��callbackReturnOn: callbackContext for: anObject

�� �� �� ^ super callbackReturnOn: callbackContext for: anObject value "<=="

�� FFIExternalType >> callbackReturnOn: callbackContext for: anObject

^ callbackContext wordResult: anObject