From 681a9955357ddf2cbc1d21b89191d0c70b2f1845 Mon Sep 17 00:00:00 2001
From: Peter Peterson <petersonpf@ornl.gov>
Date: Wed, 8 Jan 2014 14:41:00 -0500
Subject: [PATCH] Re #8686. Added real filename and line number when emitting
 errors.

Required a small refactor of the code. Hopefully the additional
comments help out.
---
 Code/Mantid/MantidPlot/src/PythonScript.cpp | 55 ++++++++++++++-------
 Code/Mantid/MantidPlot/src/PythonScript.h   |  5 +-
 2 files changed, 39 insertions(+), 21 deletions(-)

diff --git a/Code/Mantid/MantidPlot/src/PythonScript.cpp b/Code/Mantid/MantidPlot/src/PythonScript.cpp
index fefc79fa03a1..8e6daebfd072 100644
--- a/Code/Mantid/MantidPlot/src/PythonScript.cpp
+++ b/Code/Mantid/MantidPlot/src/PythonScript.cpp
@@ -223,27 +223,43 @@ void PythonScript::generateAutoCompleteList()
 }
 
 /**
- * Convert a python error state into a human-readable string
- *
- * @return A string containing the error message
+ * This emits the error signal and resets the error state
+ * of the python interpreter.
  */
-QString PythonScript::constructErrorMsg()
+void PythonScript::emit_error()
 {
+  // gil is necessary so other things don't continue
   GlobalInterpreterLock gil;
-  QString message;
-  if (!PyErr_Occurred()) 
-  {
-    return message;
-  }
+
+  // return early if nothing happened
+  if (!PyErr_Occurred())
+    return;
+
+  // get the error information out
   PyObject *exception(NULL), *value(NULL), *traceback(NULL);
   PyErr_Fetch(&exception, &value, &traceback);
+
+  // prework on the exception handling
   PyErr_NormalizeException(&exception, &value, &traceback);
   PyErr_Clear();
+
+  // convert the traceback into something useful
+  int lineNumber = 0;
+  QString filename;
+  if (traceback)
+  {
+    PyTracebackObject* tb = (PyTracebackObject*)traceback;
+    lineNumber = tb->tb_lineno;
+    filename = PyString_AsString(tb->tb_frame->f_code->co_filename);
+  }
+
+  // the error message is the full (formated) traceback
   PyObject *str_repr = PyObject_Str(value);
+  QString message;
   QTextStream msgStream(&message);
   if( value && str_repr )
   {
-    if(exception == PyExc_SyntaxError) 
+    if(exception == PyExc_SyntaxError)
     {
       msgStream << constructSyntaxErrorStr(value);
     }
@@ -253,7 +269,7 @@ QString PythonScript::constructErrorMsg()
       excTypeName = excTypeName.section(".", -1);
       msgStream << excTypeName << ": " << PyString_AsString(str_repr);
     }
-    
+
   }
   else
   {
@@ -265,7 +281,8 @@ QString PythonScript::constructErrorMsg()
   Py_XDECREF(traceback);
   Py_XDECREF(exception);
   Py_XDECREF(value);
-  return msgStream.readAll();
+
+  emit error(msgStream.readAll(), filename, lineNumber);
 }
 
 /**
@@ -468,7 +485,7 @@ QVariant PythonScript::evaluateImpl()
     }
     else
     {
-      emit error(constructErrorMsg(), "", 0);
+      emit_error();
       return QVariant();
     }
   }
@@ -538,7 +555,7 @@ QVariant PythonScript::evaluateImpl()
     }
     else
     {
-      emit error(constructErrorMsg(), "", 0);
+      emit_error();
     }
     return QVariant();
   }
@@ -567,13 +584,14 @@ bool PythonScript::executeString()
   // If an error has occurred we need to construct the error message
   // before any other python code is run
   QString msg;
-  if(!result) 
+  if(!result)
   {
-    msg = constructErrorMsg(); // Also clears error indicator
+    emit_error();
   }
   else
   {
-    msg = "Script execution finished.";
+    QString msg = "Script execution finished.";
+    emit finished(msg);
     success = true;
   }
   if(isInteractive())
@@ -583,8 +601,7 @@ bool PythonScript::executeString()
 
   Py_XDECREF(compiledCode);
   Py_XDECREF(result);
-  if(success) emit finished(msg);
-  else emit error(msg, "", 0);
+
   return success;
 }
 
diff --git a/Code/Mantid/MantidPlot/src/PythonScript.h b/Code/Mantid/MantidPlot/src/PythonScript.h
index 5b427fa1084d..86d13235632c 100644
--- a/Code/Mantid/MantidPlot/src/PythonScript.h
+++ b/Code/Mantid/MantidPlot/src/PythonScript.h
@@ -79,8 +79,6 @@ class PythonScript : public Script, MantidQt::API::WorkspaceObserver
   /// Create a list of keywords for the code completion API
   void generateAutoCompleteList();
 
-  /// Construct the error message from the stack trace (if one exists)
-  QString constructErrorMsg();
   /// Special handle for syntax errors as they have no traceback
   QString constructSyntaxErrorStr(PyObject *syntaxError);
   /// Convert a traceback to a string
@@ -185,6 +183,9 @@ class PythonScript : public Script, MantidQt::API::WorkspaceObserver
   /// Delete a Python reference to the given workspace name
   void deletePythonReference(const std::string& wsName);
 
+  /// Send out an error and clear it from python.
+  void emit_error();
+
   PythonScripting * m_pythonEnv;
   PyObject *localDict, *stdoutSave, *stderrSave;
   PyObject *m_CodeFileObject;