Added b/w compatibility for "dot" module/function

When loading a function init with a dot, this
is transformed to a proper import and the
python init configuration is changed to support
the new python loading system.

Also check for inspect errors.

Still missing: warn the user on configuration and
trapped runtime errors

src/core/qgsvectorlayer.cpp

@@ -1780,18 +1780,33 @@ bool QgsVectorLayer::readSymbology( const QDomNode& node, QString& errorMessage
     mEditFormConfig->setInitFunction( editFormInitNode.toElement().text() );
   }
 
+  QDomNode editFormInitCodeSourceNode = node.namedItem( "editforminitcodesource" );
+  if ( !editFormInitCodeSourceNode.isNull() || ( !editFormInitCodeSourceNode.isNull() && !editFormInitCodeSourceNode.toElement().text().isEmpty() ) )
+  {
+    mEditFormConfig->setInitCodeSource(( QgsEditFormConfig::PythonInitCodeSource ) editFormInitCodeSourceNode.toElement().text().toInt() );
+  }
+
   QDomNode editFormInitCodeNode = node.namedItem( "editforminitcode" );
   if ( !editFormInitCodeNode.isNull() )
   {
     mEditFormConfig->setInitCode( editFormInitCodeNode.toElement().text() );
   }
 
-  QDomNode editFormInitCodeSourceNode = node.namedItem( "editforminitcodesource" );
-  if ( !editFormInitCodeSourceNode.isNull() || ( !editFormInitCodeSourceNode.isNull() && !editFormInitCodeSourceNode.toElement().text().isEmpty() ) )
+  // Temporary < 2.12 b/w compatibility "dot" support patch
+  // @see: https://github.com/qgis/QGIS/pull/2498
+  // For b/w compatibility, check if there's a dot in the function name
+  // and if yes, transform it in an import statement for the module
+  // and set the PythonInitCodeSource to CodeSourceDialog
+  QString initFunction = mEditFormConfig->initFunction();
+  int dotPos = initFunction.lastIndexOf( '.' );
+  if ( dotPos >= 0 ) // It's a module
   {
-    mEditFormConfig->setInitCodeSource(( QgsEditFormConfig::PythonInitCodeSource ) editFormInitCodeSourceNode.toElement().text().toInt() );
+    mEditFormConfig->setInitCodeSource( QgsEditFormConfig::PythonInitCodeSource::CodeSourceDialog );
+    mEditFormConfig->setInitFunction( initFunction.mid( dotPos + 1 ) );
+    mEditFormConfig->setInitCode( QString( "from %1 import %2\n" ).arg( initFunction.left( dotPos ), initFunction.mid( dotPos + 1 ) ) );
   }
 
+
   QDomNode editFormInitFilePathNode = node.namedItem( "editforminitfilepath" );
   if ( !editFormInitFilePathNode.isNull() || ( !editFormInitFilePathNode.isNull() && !editFormInitFilePathNode.toElement().text().isEmpty() ) )
   {

src/gui/qgsattributeform.cpp

@@ -633,34 +633,41 @@ void QgsAttributeForm::initPython()
 
     QgsPythonRunner::run( "import inspect" );
     QString numArgs;
-    QgsPythonRunner::eval( QString( "len(inspect.getargspec(%1)[0])" ).arg( initFunction ), numArgs );
 
-    static int sFormId = 0;
-    mPyFormVarName = QString( "_qgis_featureform_%1_%2" ).arg( mFormNr ).arg( sFormId++ );
+    // Check for eval result
+    if ( QgsPythonRunner::eval( QString( "len(inspect.getargspec(%1)[0])" ).arg( initFunction ), numArgs ) )
+    {
+      static int sFormId = 0;
+      mPyFormVarName = QString( "_qgis_featureform_%1_%2" ).arg( mFormNr ).arg( sFormId++ );
 
-    QString form = QString( "%1 = sip.wrapinstance( %2, qgis.gui.QgsAttributeForm )" )
-                   .arg( mPyFormVarName )
-                   .arg(( unsigned long ) this );
+      QString form = QString( "%1 = sip.wrapinstance( %2, qgis.gui.QgsAttributeForm )" )
+                     .arg( mPyFormVarName )
+                     .arg(( unsigned long ) this );
 
-    QgsPythonRunner::run( form );
+      QgsPythonRunner::run( form );
 
-    QgsDebugMsg( QString( "running featureForm init: %1" ).arg( mPyFormVarName ) );
+      QgsDebugMsg( QString( "running featureForm init: %1" ).arg( mPyFormVarName ) );
 
-    // Legacy
-    if ( numArgs == "3" )
-    {
-      addInterface( new QgsAttributeFormLegacyInterface( initFunction, mPyFormVarName, this ) );
+      // Legacy
+      if ( numArgs == "3" )
+      {
+        addInterface( new QgsAttributeFormLegacyInterface( initFunction, mPyFormVarName, this ) );
+      }
+      else
+      {
+#if 0
+        QString expr = QString( "%1(%2)" )
+                       .arg( mLayer->editFormInit() )
+                       .arg( mPyFormVarName );
+        QgsAttributeFormInterface* iface = QgsPythonRunner::evalToSipObject<QgsAttributeFormInterface*>( expr, "QgsAttributeFormInterface" );
+        if ( iface )
+          addInterface( iface );
+#endif
+      }
     }
     else
     {
-#if 0
-      QString expr = QString( "%1(%2)" )
-                     .arg( mLayer->editFormInit() )
-                     .arg( mPyFormVarName );
-      QgsAttributeFormInterface* iface = QgsPythonRunner::evalToSipObject<QgsAttributeFormInterface*>( expr, "QgsAttributeFormInterface" );
-      if ( iface )
-        addInterface( iface );
-#endif
+      QgsLogger::warning( QString( "There was an error evaluating the python init function!" ) );
     }
   }
 }