Demonstration of calling a Wren method from the current embedding API. More on Wren: http://wren.io/ Derived from: https://github.com/munificent/wren/issues/194

demo_foreign.c

#include <assert.h>
#include <string.h>
#include <stdio.h>
#include "wren.h"

void logFromWren(WrenVM *vm) {
    //double x = wrenGetArgumentDouble(vm, 0);  // returns 0 in this setting
    const char *message = wrenGetArgumentString(vm, 1);
    printf("logFromWren: %s\n", message);
}

WrenForeignMethodFn bindForeignMethod(WrenVM* vm, const char* module, const char* className, bool isStatic, const char* signature) {
    if (strcmp(module, "main") == 0
        && strcmp(className, "Interface") == 0
        && strcmp(signature, "log(_)") == 0) {
        return logFromWren;
    }
    return NULL;
}

void demo_foreign() {
    
    WrenConfiguration config = { 0 };
    config.bindForeignMethodFn = bindForeignMethod;
    WrenVM *vm = wrenNewVM(&config);
    
    const char wrenSource[] = ""
    "var Counter = 0 \n"
    "class Interface { \n"
    "  static say(text) { \n"
    "    Counter = Counter + 1 \n"
    "    IO.print(\"Interface.say() called with: \", text, \"  Counter = \", Counter) \n"
    "    log(\"Hello from Wren!\") \n"
    "  } \n"
    "  foreign static log(message) \n"
    "} \n";
    
    WrenInterpretResult result = wrenInterpret(vm, "dummy.wren", wrenSource);
    assert(result == WREN_RESULT_SUCCESS);
    
    WrenMethod *method = wrenGetMethod(vm, "main", "Interface", "say(_)");
    
    wrenCall(vm, method, "s", "Howdy!");
    wrenCall(vm, method, "s", "Again!");
    
    wrenReleaseMethod(vm, method);
    
    wrenFreeVM(vm);
}

demo_method_call.c

#include <assert.h>
#include "wren.h"

void demo_method_call() {
    
    WrenConfiguration config = { 0 };
    WrenVM *vm = wrenNewVM(&config);

    const char wrenSource[] = ""
    "class Foo { \n"
    "  static say(text) { \n"
    "    IO.print(\"Foo.say() called with: \", text) \n"
    "  } \n"
    "}";
    
    WrenInterpretResult result = wrenInterpret(vm, "dummy.wren", wrenSource);
    assert(result == WREN_RESULT_SUCCESS);
    
    WrenMethod *method = wrenGetMethod(vm, "main", "Foo", "say(_)");
    
    wrenCall(vm, method, "s", "Howdy!"); // "Foo.say() called with: Howdy!"
    
    wrenReleaseMethod(vm, method);

    wrenFreeVM(vm);
    
}