> On 12 Dec 2017, at 19:27, C. Keith Ray via swift-evolution > <swift-evolution@swift.org> wrote: > > in https://gist.github.com/lattner/b016e1cf86c43732c8d82f90e5ae5438 > <https://gist.github.com/lattner/b016e1cf86c43732c8d82f90e5ae5438> > > there is this statement: > > "For this reason, the compiler only permits conformance of this protocol on > the original type definition, not extensions" > > and this example: > > extension JSON : DynamicMemberLookupProtocol { > > > Contradictory? > I think this is just an oversight after it was changed that this protocol could not conform on extensions.
> > Also... > > Calling Java from C is done like the following, how would one do it in Swift > using this proposal? > > ( Example from > https://www.ibm.com/developerworks/java/tutorials/j-jni/j-jni.html > <https://www.ibm.com/developerworks/java/tutorials/j-jni/j-jni.html> ) > > Java code: > > public class Sample2 > { > public static int intMethod(int n) { > return n*n; > } > > public static boolean booleanMethod(boolean bool) { > return !bool; > } > } > > C Code: > > #include <jni.h> > > #ifdef _WIN32 > #define PATH_SEPARATOR ';' > #else > #define PATH_SEPARATOR ':' > #endif > int main() > { > JavaVMOption options[1]; > JNIEnv *env; > JavaVM *jvm; > JavaVMInitArgs vm_args; > long status; > jclass cls; > jmethodID mid; > jint square; > jboolean not; > > options[0].optionString = "-Djava.class.path=."; > memset(&vm_args, 0, sizeof(vm_args)); > vm_args.version = JNI_VERSION_1_2; > vm_args.nOptions = 1; > vm_args.options = options; > status = JNI_CreateJavaVM(&jvm, (void**)&env, &vm_args); > > if (status != JNI_ERR) > { > cls = (*env)->FindClass(env, "Sample2"); > > if (cls !=0) > { > mid = (*env)->GetStaticMethodID(env, cls, "intMethod", "(I)I"); > > if (mid !=0) > { > square = (*env)->CallStaticIntMethod(env, cls, mid, 5); > printf("Result of intMethod: %d\n", square); > } > > mid = (*env)->GetStaticMethodID(env, cls, "booleanMethod", "(Z)Z"); > > if (mid !=0) > { > not = (*env)->CallStaticBooleanMethod(env, cls, mid, 1); > printf("Result of booleanMethod: %d\n", not); > } > } > (*jvm)->DestroyJavaVM(jvm); > return 0; > } > else > return -1; > } > I think this should be up to whoever implements the Java wrapper. This proposal doesn’t specifically address the implementation of specific language interop’s. It just gives the writer a way to give their implementation a nice syntactic view in the language.
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