[PyQt] Debug output for pyqt5.dll Designer plugin

[Kyle Altendorf]

Is there any interest in adding some debug output to the pyqt5.dll 
Designer plugin?  In Windows it fails (almost) completely silently.

The patch included below is incomplete in that it provides only a very 
little bit of debugging info but works using both QMessageBox and 
QDebug.  The QDebug output is available in Windows via at least 
DebugView.

https://technet.microsoft.com/en-us/sysinternals/debugview.aspx

The patch is inline below as well as attached.

Cheers,
-kyle



diff -ru clean/PyQt5_gpl-5.7/designer/pluginloader.cpp 
PyQt5_gpl-5.7-designer/designer/pluginloader.cpp
--- clean/PyQt5_gpl-5.7/designer/pluginloader.cpp       2016-07-25 
14:56:44.000000000 -0700
+++ PyQt5_gpl-5.7-designer/designer/pluginloader.cpp    2016-08-09 
06:08:59.618045800 -0700
@@ -33,13 +33,19 @@
  #include <QStringList>
  #include <QVector>
  #include <QtDesigner>
+#include <QDebug>
+
+#include <QMessageBox>

  #include "../qpy/QtDesigner/qpydesignercustomwidgetplugin.h"

+#define debug() qDebug() << "pyqt5.dll: "
+

  // Construct the collection of Python widgets.
  PyCustomWidgets::PyCustomWidgets(QObject *parent) : QObject(parent)
  {
+    debug() << "PyCustomWidgets::PyCustomWidgets()";
      // Get the default list of directories to search.  These correspond 
to a
      // standard "python" subdirectory of all the places that Designer 
looks for
      // its own plugins.
@@ -127,12 +133,21 @@
          // possible.
          if (!Py_IsInitialized())
          {
+            debug() << "PyCustomWidgets::PyCustomWidgets():  Attempting 
to load" PYTHON_LIB;
+
              QLibrary library(PYTHON_LIB);

              library.setLoadHints(QLibrary::ExportExternalSymbolsHint);

              if (!library.load())
+            {
+                debug() << "PyCustomWidgets::PyCustomWidgets():  
Loading " PYTHON_LIB " failed";
+
+                QMessageBox::critical(NULL, "PyQt5 Qt Designer Plugin", 
"Failed to load " PYTHON_LIB);
                  return;
+            }
+
+            debug() << "PyCustomWidgets::PyCustomWidgets():  Loading " 
PYTHON_LIB " succeeded";

              Py_Initialize();
          }
@@ -143,7 +158,12 @@
              sys_path = getModuleAttr("sys", "path");

              if (!sys_path)
+            {
+                debug() << "PyCustomWidgets::PyCustomWidgets():  
sys_path not found";
                  return;
+            }
+
+            debug() << "PyCustomWidgets::PyCustomWidgets():  sys_path: 
" << PyUnicode_AS_DATA(sys_path);
          }

          // Make sure we have sip.unwrapinstance.
@@ -152,7 +172,10 @@
              sip_unwrapinstance = getModuleAttr("sip", 
"unwrapinstance");

              if (!sip_unwrapinstance)
+            {
+                debug() << "PyCustomWidgets::PyCustomWidgets():  
sip_unwrapinstance not found";
                  return;
+            }
          }

          // Convert the directory to a Python object with native 
separators.
@@ -300,6 +323,7 @@

      if (!mod)
      {
+        debug() << "PyCustomWidgets::getModuleAttr():  failed to 
import" << module;
          PyErr_Print();
          return 0;
      }
@@ -310,6 +334,7 @@

      if (!obj)
      {
+        debug() << "PyCustomWidgets::getModuleAttr():  failed to get 
attribute" << attr << " from " << module;
          PyErr_Print();
          return 0;
      }
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