From 82acbfdc322b736e0f78ccc76de3a8ec7d863ed8 Mon Sep 17 00:00:00 2001
From: wusspuss <wusspuss@ya.ru>
Date: Fri, 28 Jan 2022 14:13:58 +1000
Subject: [PATCH] Add get_callback function to get the python callable
 registered with register_callback

---
 generic/tohil.c         | 23 +++++++++++++++++++++++
 pysrc/tohil/__init__.py |  1 +
 tests/test_register.py  |  4 ++++
 3 files changed, 28 insertions(+)

diff --git a/generic/tohil.c b/generic/tohil.c
index 277ae7d..33e15cc 100644
--- a/generic/tohil.c
+++ b/generic/tohil.c
@@ -4541,6 +4541,27 @@ tohil_register_callback(PyObject *m, PyObject *args, PyObject *kwargs)
     Py_RETURN_NONE;
 }
 
+static PyObject *
+tohil_get_callback(PyObject *m, PyObject *args, PyObject *kwargs)
+{
+  Tcl_Interp *interp = tohilstate(m)->interp;
+  Tcl_CmdInfo cmdinfo;
+  char * name;
+  static char *kwlist[] = {"name", NULL};
+  if (!PyArg_ParseTupleAndKeywords(args, kwargs, "s", kwlist, &name)) {
+        return NULL;
+  }
+  if (!Tcl_GetCommandInfo(interp, name, &cmdinfo)) {
+    PyErr_SetString(PyExc_KeyError, "no such command");
+    return NULL;
+  }
+  if (cmdinfo.objProc == PythonCmd) {
+    return ((PythonCmd_ClientData *) cmdinfo.objClientData)->func;
+  } else {
+    PyErr_SetString(PyExc_KeyError, "Not a python callback ");
+    return NULL;
+  }
+}
 //
 // python C extension structure defining functions
 //
@@ -4561,6 +4582,8 @@ static PyMethodDef TohilMethods[] = {
     {"result", (PyCFunction)tohil_result, METH_VARARGS | METH_KEYWORDS, "return the tcl interpreter result object"},
     {"register_callback", (PyCFunction)tohil_register_callback, METH_VARARGS | METH_KEYWORDS,
      "Register a Python callable so it can be called directly from Tcl as a command"},
+    {"get_callback", (PyCFunction)tohil_get_callback, METH_VARARGS | METH_KEYWORDS,
+     "Get the Python callable from a Tcl command registered with tohil.register_callback"},
     {NULL, NULL, 0, NULL} /* Sentinel */
 };
 
diff --git a/pysrc/tohil/__init__.py b/pysrc/tohil/__init__.py
index fb447d6..17ab427 100644
--- a/pysrc/tohil/__init__.py
+++ b/pysrc/tohil/__init__.py
@@ -293,6 +293,7 @@ def rivet():
     incr,
     result,
     register_callback,
+    get_callback,
     __version__,
 )
 
diff --git a/tests/test_register.py b/tests/test_register.py
index 21120c8..197284b 100644
--- a/tests/test_register.py
+++ b/tests/test_register.py
@@ -51,3 +51,7 @@ def setflag():
             time.sleep(.05)
         assert flag
 
+    def test_register_get(self):
+        func = lambda: None
+        tohil.register_callback("func", func)
+        self.assertEqual(tohil.get_callback("func"), func)