Add support for enabling stdout/stderr redirection

Author: jcfr

src/PythonQt.cpp

@@ -135,7 +135,7 @@ void PythonQt::init(int flags, const QByteArray& pythonQtModuleName)
     PythonQtRegisterToolClassesTemplateConverter(quint32);
     PythonQtRegisterToolClassesTemplateConverter(qint64);
     PythonQtRegisterToolClassesTemplateConverter(quint64);
-    
+
 #ifdef PYTHONQT_SUPPORT_ML_TYPES
     PythonQtMethodInfo::addParameterTypeAlias("QList<MLfloat>", "QList<float>");
     PythonQtMethodInfo::addParameterTypeAlias("QVector<MLfloat>", "QVector<float>");
@@ -295,7 +295,7 @@ void PythonQt::init(int flags, const QByteArray& pythonQtModuleName)
       "QtFatalMsg",
       "QtSystemMsg"
     };
-    
+
     for (auto i = 0u; i < sizeof(enumValues)/sizeof(int); i++) {
       PyObject* obj = PyInt_FromLong(enumValues[i]);
       if (PyModule_AddObject(pack, enumNames[i], obj) == 0) {
@@ -706,7 +706,7 @@ PyObject* PythonQtPrivate::wrapPtr(void* ptr, const QByteArray& name, bool passO
       return (PyObject*)wrap;
     }
 
-    // not a known QObject, try to wrap via foreign wrapper factories 
+    // not a known QObject, try to wrap via foreign wrapper factories
     PyObject* foreignWrapper = nullptr;
     for (int i=0; i<_foreignWrapperFactories.size(); i++) {
       foreignWrapper = _foreignWrapperFactories.at(i)->wrap(name, ptr);
@@ -1097,7 +1097,7 @@ PythonQtObjectPtr PythonQt::parseFileWithPythonLoaders(const QString& file)
     loader.setNewRef(callAndReturnPyObject(loaderClass, args));
     QVariantList args2;
     args2 << dummy;
-    PythonQtObjectPtr getCode; 
+    PythonQtObjectPtr getCode;
     getCode.setNewRef(PyObject_GetAttrString(loader, "get_code"));
     result.setNewRef(callAndReturnPyObject(getCode, args2));
     if (!result) {
@@ -1344,28 +1344,28 @@ PyObject* PythonQt::getObjectByType(const QString& typeName)
   sys.setNewRef(PyImport_ImportModule("sys"));
   PythonQtObjectPtr modules = lookupObject(sys, "modules");
   Q_ASSERT(PyDict_Check(modules));
-  
+
   QStringList tmp = typeName.split(".");
   QString simpleTypeName = tmp.takeLast();
   QString moduleName = tmp.join(".");
-  
+
   PyObject* object = nullptr;
   PyObject* moduleObject = PyDict_GetItemString(modules, QStringToPythonCharPointer(moduleName));
   if (moduleObject) {
     object = PyObject_GetAttrString(moduleObject, QStringToPythonCharPointer(simpleTypeName));
   }
-  
+
   if (!object) {
     moduleObject = PyDict_GetItemString(modules, "__builtin__");
     if (moduleObject) {
       object = PyObject_GetAttrString(moduleObject, QStringToPythonCharPointer(simpleTypeName));
     }
   }
-  
+
   PyErr_Clear();
   return object;
 }
-  
+
 QStringList PythonQt::introspectType(const QString& typeName, ObjectType type)
 {
   QStringList results;
@@ -1876,18 +1876,22 @@ void PythonQt::initPythonQtModule(bool redirectStdOut, const QByteArray& pythonQ
   PythonQtObjectPtr sys;
   sys.setNewRef(PyImport_ImportModule("sys"));
 
-  if (redirectStdOut) {
-    PythonQtObjectPtr out;
-    PythonQtObjectPtr err;
-    // create a redirection object for stdout and stderr
-    out = PythonQtStdOutRedirectType.tp_new(&PythonQtStdOutRedirectType,nullptr, nullptr);
-    ((PythonQtStdOutRedirect*)out.object())->_cb = stdOutRedirectCB;
-    err = PythonQtStdOutRedirectType.tp_new(&PythonQtStdOutRedirectType,nullptr, nullptr);
-    ((PythonQtStdOutRedirect*)err.object())->_cb = stdErrRedirectCB;
-    // replace the built in file objects with our own objects
-    PyModule_AddObject(sys, "stdout", out);
-    PyModule_AddObject(sys, "stderr", err);
-  }
+  // Backup original 'sys.stdout' and 'sys.stderr'
+  PyModule_AddObject(sys, "pythonqt_original_stdout", PyObject_GetAttrString(sys, "stdout"));
+  PyModule_AddObject(sys, "pythonqt_original_stderr", PyObject_GetAttrString(sys, "stderr"));
+
+  // Create a redirection object for stdout and stderr
+  PythonQtObjectPtr out;
+  PythonQtObjectPtr err;
+  out = PythonQtStdOutRedirectType.tp_new(&PythonQtStdOutRedirectType,nullptr, nullptr);
+  ((PythonQtStdOutRedirect*)out.object())->_cb = stdOutRedirectCB;
+  err = PythonQtStdOutRedirectType.tp_new(&PythonQtStdOutRedirectType,nullptr, nullptr);
+  ((PythonQtStdOutRedirect*)err.object())->_cb = stdErrRedirectCB;
+  // replace the built in file objects with our own objects
+  PyModule_AddObject(sys, "pythonqt_stdout", out);
+  PyModule_AddObject(sys, "pythonqt_stderr", err);
+
+  setRedirectStdOutCallbackEnabled(redirectStdOut);
 
   // add PythonQt to the list of builtin module names
   PyObject *old_module_names = PyObject_GetAttrString(sys.object(),"builtin_module_names");
@@ -1909,12 +1913,48 @@ void PythonQt::initPythonQtModule(bool redirectStdOut, const QByteArray& pythonQ
 #endif
 }
 
+bool PythonQt::redirectStdOutCallbackEnabled() const
+{
+  PythonQtObjectPtr sys;
+  sys.setNewRef(PyImport_ImportModule("sys"));
+
+  PythonQtObjectPtr pythonqt_stdout;
+  pythonqt_stdout.setNewRef(PyObject_GetAttrString(sys.object(), "pythonqt_stdout"));
+
+  PythonQtObjectPtr stdout;
+  stdout.setNewRef(PyObject_GetAttrString(sys.object(), "stdout"));
+
+  return PyObject_RichCompareBool(pythonqt_stdout.object(), stdout.object(), Py_EQ);
+}
+
+void PythonQt::setRedirectStdOutCallbackEnabled(bool enabled)
+{
+  PythonQtObjectPtr sys;
+  sys.setNewRef(PyImport_ImportModule("sys"));
+
+  if (enabled) {
+    if( PyObject_HasAttrString(sys.object(), "pythonqt_stdout") ) {
+      PyModule_AddObject(sys.object(), "stdout", PyObject_GetAttrString(sys.object(), "pythonqt_stdout"));
+    }
+    if( PyObject_HasAttrString(sys.object(), "pythonqt_stderr") ) {
+      PyModule_AddObject(sys.object(), "stderr", PyObject_GetAttrString(sys.object(), "pythonqt_stderr"));
+    }
+  } else {
+    if( PyObject_HasAttrString(sys.object(), "pythonqt_original_stdout") ) {
+      PyModule_AddObject(sys.object(), "stdout", PyObject_GetAttrString(sys.object(), "pythonqt_original_stdout"));
+    }
+    if( PyObject_HasAttrString(sys.object(), "pythonqt_original_stderr") ) {
+      PyModule_AddObject(sys.object(), "stderr", PyObject_GetAttrString(sys.object(), "pythonqt_original_stderr"));
+    }
+  }
+}
+
 QString PythonQt::getReturnTypeOfWrappedMethod(PyObject* module, const QString& name)
 {
   QStringList tmp = name.split(".");
   QString methodName = tmp.takeLast();
   QString variableName = tmp.join(".");
-  PythonQtObjectPtr variableObject = lookupObject(module, variableName);  
+  PythonQtObjectPtr variableObject = lookupObject(module, variableName);
   if (variableObject.isNull()) {
     // try lookup by interpreting the variableName as a type
     QString type = getReturnTypeOfWrappedMethod(variableName, methodName);
@@ -1943,9 +1983,9 @@ QString PythonQt::getReturnTypeOfWrappedMethodHelper(const PythonQtObjectPtr& va
   if (methodObject.isNull()) {
     return "";
   }
-    
+
   QString type;
-  
+
   if (PythonQtUtils::isPythonClassType(methodObject)) {
     // the methodObject is not a method, but the name of a type/class. This means
     // a constructor is called. Return the context.
@@ -2376,13 +2416,13 @@ void PythonQtPrivate::callMethodInPython(QMetaMethod &method, PythonQtInstanceWr
 QString PythonQtPrivate::getSignature(PyObject* object)
 {
   QString signature;
-  
+
   if (object) {
     PyMethodObject* method = nullptr;
     PyFunctionObject* func = nullptr;
-    
+
     bool decrefMethod = false;
-    
+
     if (PythonQtUtils::isPythonClassType(object)) {
       method = (PyMethodObject*)PyObject_GetAttrString(object, "__init__");
       decrefMethod = true;
@@ -2418,7 +2458,7 @@ QString PythonQtPrivate::getSignature(PyObject* object)
         }
       }
     }
-    
+
     if (func) {
       QString funcName;
       PyObject* s = PyObject_GetAttrString((PyObject*)func, "__name__");
@@ -2435,7 +2475,7 @@ QString PythonQtPrivate::getSignature(PyObject* object)
           Py_DECREF(s);
         }
       }
-        
+
       QStringList arguments;
       QStringList defaults;
       QString varargs;
@@ -2465,7 +2505,7 @@ QString PythonQtPrivate::getSignature(PyObject* object)
         }
         Py_DECREF(co_varnames);
       }
-      
+
       PyObject* defaultsTuple = func->func_defaults;
       if (defaultsTuple) {
         Q_ASSERT(PyTuple_Check(defaultsTuple));
@@ -2477,7 +2517,7 @@ QString PythonQtPrivate::getSignature(PyObject* object)
           Py_DECREF(s);
         }
       }
-      
+
       int firstdefault = arguments.size() - defaults.size();
       for (int i=0; i<arguments.size(); i++) {
         if (!signature.isEmpty()) { signature += ", "; }
@@ -2498,12 +2538,12 @@ QString PythonQtPrivate::getSignature(PyObject* object)
       }
       signature = funcName + "(" + signature + ")";
     }
-    
+
     if (method && decrefMethod) {
       Py_DECREF(method);
     }
   }
-  
+
   return signature;
 }
 

src/PythonQt.h

@@ -268,6 +268,18 @@ class PYTHONQT_EXPORT PythonQt : public QObject {
 
   //@}
 
+  //---------------------------------------------------------------------------
+  //! \name Standard output handling
+  //@{
+
+  //! return \a true if std out/err redirection is enabled.
+  bool redirectStdOutCallbackEnabled() const;
+
+  //! enable or disable std out/err redirection to pythonStdOut() and pythonStdErr() signals.
+  void setRedirectStdOutCallbackEnabled(bool enabled);
+
+  //@}
+
   //---------------------------------------------------------------------------
   //! \name Modules
   //@{