feat: add instanceMethod (#68)

Co-authored-by: Elias Sjögreen <elias@5monkeys.se>

src/python.ts

@@ -975,6 +975,34 @@ export class Python {
  callback(cb: PythonJSCallback): Callback {
  return new Callback(cb);
  }
+
+ /**
+ * Creates a Python instance method from a JavaScript callback.
+ *
+ * @description
+ * This method takes a JavaScript callback function and creates a Python instance method.
+ *
+ * The method returns both the created Python instance method and the Callback object.
+ * The Callback object is returned to allow the user to explicitly call its `destroy`
+ * method when it's no longer needed, ensuring proper resource management and
+ * freeing of memory.
+ *
+ * @example
+ * const [pyMethod, callback] = instanceMethod(myJSFunction);
+ * // Use pyMethod as needed
+ * // ...
+ * // When done, explicitly free the callback
+ * callback.destroy();
+ */
+ instanceMethod(cb: PythonJSCallback): [PyObject, Callback] {
+ const pythonCb = python.callback(cb);
+ const method = new PyObject(
+ py.PyInstanceMethod_New(
+ PyObject.from(pythonCb).handle,
+ ),
+ );
+ return [method, pythonCb];
+ }
 }
 
 /**

src/symbols.ts

@@ -249,4 +249,9 @@ export const SYMBOLS = {
  parameters: ["buffer", "pointer", "pointer"],
  result: "pointer",
  },
+
+ PyInstanceMethod_New: {
+ parameters: ["pointer"],
+ result: "pointer",
+ },
 } as const;

test/test.ts

@@ -325,6 +325,26 @@ Deno.test("exceptions", async (t) => {
  });
 });
 
+Deno.test("instance method", () => {
+ const { A } = python.runModule(
+ `
+class A:
+ def b(self):
+ return 4
+ `,
+ "cb_test.py",
+ );
+
+ const [m, cb] = python.instanceMethod((_args, self) => {
+ return self.b();
+ });
+ // Modifying PyObject modifes A
+ PyObject.from(A).setAttr("a", m);
+
+ assertEquals(new A().a.call().valueOf(), 4);
+ cb.destroy();
+});
+
 Deno.test("callbacks have signature", async (t) => {
  const inspect = python.import("inspect");