Merge pull request #16 from debsankha/fix_exception_handling

Fix exception handling

Author: andsor

.travis.yml

@@ -0,0 +1,21 @@
+sudo: false
+
+language: python
+
+python:
+- '2.7'
+- '3.6'
+
+branches:
+  only:
+  - master
+  - fix_exception_handling
+
+before_install:
+- pwd
+- pip install cython pytest pytest-mock
+- pip install -r requirements.txt
+- pip install ./
+
+script:
+- pytest -vvv --import-mode=append

devs/adevs_python.hpp

@@ -26,7 +26,6 @@
 #include "adevs.h"
 
 
-
 namespace pydevs {
 
 
@@ -86,8 +85,14 @@ class Atomic: public AtomicBase {
 	virtual void delta_int() {
 
 		bool isDefined = this->pythonObject_ && this->deltaIntFunc_;
-		if (isDefined)
+		if (isDefined){
 			this->deltaIntFunc_ (this->pythonObject_);
+			if (PyErr_Occurred())
+			{
+				std::string error_message = get_PyExceptionAsString();
+				throw std::runtime_error(error_message);
+			}
+		}
 		else
 			throw std::bad_function_call();
 
@@ -98,10 +103,14 @@ class Atomic: public AtomicBase {
 	virtual void delta_ext (Time e, const IOBag& xb) {
 
 		bool isDefined = this->pythonObject_ && this->deltaExtFunc_;
-		if (isDefined)
-			this->deltaExtFunc_ (
-				this->pythonObject_, e, xb
-			);
+		if (isDefined){
+			this->deltaExtFunc_ (this->pythonObject_, e, xb);
+			if (PyErr_Occurred())
+			{
+				std::string error_message = get_PyExceptionAsString();
+				throw std::runtime_error(error_message);
+			}
+		}
 		else
 			throw std::bad_function_call();
 
@@ -112,13 +121,16 @@ class Atomic: public AtomicBase {
 	virtual void delta_conf (const IOBag& xb) {
 
 		bool isDefined = this->pythonObject_ && this->deltaConfFunc_;
-		if (isDefined)
-			this->deltaConfFunc_ (
-				this->pythonObject_, xb
-			);
+		if (isDefined){
+			this->deltaConfFunc_ (this->pythonObject_, xb);
+			if (PyErr_Occurred())
+			{
+				std::string error_message = get_PyExceptionAsString();
+				throw std::runtime_error(error_message);
+			}
+		}
 		else
 			throw std::bad_function_call();
-
 	}
 
 
@@ -127,11 +139,18 @@ class Atomic: public AtomicBase {
 
 		bool isDefined = this->pythonObject_ && this->outputFunc_;
 		if (isDefined)
-			this->outputFunc_ (
-				this->pythonObject_, yb
-			);
+		{
+			this->outputFunc_ (this->pythonObject_, yb);
+			if (PyErr_Occurred())
+			{
+				std::string error_message = get_PyExceptionAsString();
+				throw std::runtime_error(error_message);
+			}
+		}
 		else
+		{
 			throw std::bad_function_call();
+		}
 
 	}
 
@@ -171,6 +190,39 @@ class Atomic: public AtomicBase {
 	}
 
 
+	std::string get_PyExceptionAsString()
+	{
+		// now we will try to get the python traceback.
+		// see https://stackoverflow.com/questions/1796510/accessing-a-python-traceback-from-the-c-api
+		// for longer discussion on how to do it.
+		PyObject *ptype, *pvalue, *ptraceback;
+		PyObject *pystr, *pystr_unic;
+
+		std::string error_desc;
+		PyErr_Fetch(&ptype, &pvalue, &ptraceback);
+		if (pvalue == NULL){
+			error_desc = {"No information on the occured exception available"};
+		}
+		else {
+			#if PY_MAJOR_VERSION < 3
+			pystr = PyObject_Unicode(pvalue);
+			pystr_unic = PyUnicode_AsEncodedString(pystr, "utf-8", "ignore"); // same in py2 and py3
+			error_desc = {PyBytes_AsString(pystr_unic)};
+			#else
+			pystr = PyObject_Str(pvalue);
+			pystr_unic = PyUnicode_AsEncodedString(pystr, "utf-8", "ignore");
+			error_desc = {PyBytes_AsString(pystr_unic)};
+			#endif
+
+			Py_XDECREF(pystr);
+			Py_XDECREF(pystr_unic);
+		}
+		Py_XDECREF(ptype);
+		Py_XDECREF(pvalue);
+		Py_XDECREF(ptraceback);
+
+		return "Python traceback follows:\n" + error_desc;
+	}
 
 private:
 
@@ -180,7 +232,6 @@ class Atomic: public AtomicBase {
 	const DeltaConfFunc deltaConfFunc_;
 	const OutputFunc outputFunc_;
 	const TaFunc taFunc_;
-
 };
 
 

devs/cadevs.pxd

@@ -103,5 +103,6 @@ cdef extern from "adevs_python.hpp" namespace "pydevs":
         Simulator(Atomic*) except +
         Simulator(Digraph*) except +
         Time nextEventTime() except *
-        void executeNextEvent() except *
-        void executeUntil(Time) except *
+        void executeNextEvent() except +* # the +* signifies this can raise
+                                          # both python and c++ exceptions
+        void executeUntil(Time) except +*