Add beginnings of EventPort wrapping

capnp/helpers/asyncHelper.h

@@ -0,0 +1,29 @@
+#pragma once
+
+#include "kj/async.h"
+#include "Python.h"
+
+class PyEventPort: public kj::EventPort {
+public:
+  PyEventPort(PyObject * _py_event_port): py_event_port(_py_event_port) {
+    // We don't need to incref/decref, since this C++ class will be owned by the Python wrapper class, and we'll make sure the python class doesn't refcount to 0 elsewhere.
+    // Py_INCREF(py_event_port);
+  }
+  virtual void wait() {
+    PyObject_CallMethod(py_event_port, const_cast<char *>("wait"), NULL);
+  }
+
+  virtual void poll() {
+    PyObject_CallMethod(py_event_port, const_cast<char *>("poll"), NULL);
+  }
+
+  virtual void setRunnable(bool runnable) {
+    PyObject * arg = Py_False;
+    if (runnable)
+      arg = Py_True;
+    PyObject_CallMethod(py_event_port, const_cast<char *>("set_runnable"), const_cast<char *>("o"), arg);
+  }
+
+private:
+  PyObject * py_event_port;
+};