Indicate exception types to sip

Exposes the full Python exception when an error occurs in createInstance()

Author: nyalldawson

python/core/auto_generated/processing/qgsprocessingalgorithm.sip.in

@@ -63,7 +63,7 @@ a pre-initialized copy of the algorithm.
 
 
 
-    QgsProcessingAlgorithm *create( const QVariantMap &configuration = QVariantMap() ) const /TransferBack/;
+    QgsProcessingAlgorithm *create( const QVariantMap &configuration = QVariantMap() ) const throw( QgsProcessingException ) /TransferBack/;
 %Docstring
 Creates a copy of the algorithm, ready for execution.
 
@@ -76,6 +76,9 @@ and outputs according to this configuration. This is generally used only for
 algorithms in a model, allowing them to adjust their behavior at run time
 according to some user configuration.
 
+Raises a QgsProcessingException if a new algorithm instance could not be created,
+e.g. if there is an issue with the subclass' createInstance() method.
+
 .. seealso:: :py:func:`initAlgorithm`
 %End
 
@@ -401,7 +404,7 @@ Associates this algorithm with its provider. No transfer of ownership is involve
 
   protected:
 
-    virtual QgsProcessingAlgorithm *createInstance() const = 0 /Factory/;
+    virtual QgsProcessingAlgorithm *createInstance() const = 0 /Factory,VirtualErrorHandler=processing_exception_handler/;
 %Docstring
 Creates a new instance of the algorithm class.
 

src/core/processing/qgsprocessingalgorithm.h

@@ -122,9 +122,12 @@ class CORE_EXPORT QgsProcessingAlgorithm
      * algorithms in a model, allowing them to adjust their behavior at run time
      * according to some user configuration.
      *
+     * Raises a QgsProcessingException if a new algorithm instance could not be created,
+     * e.g. if there is an issue with the subclass' createInstance() method.
+     *
      * \see initAlgorithm()
      */
-    QgsProcessingAlgorithm *create( const QVariantMap &configuration = QVariantMap() ) const SIP_TRANSFERBACK;
+    QgsProcessingAlgorithm *create( const QVariantMap &configuration = QVariantMap() ) const SIP_THROW( QgsProcessingException ) SIP_TRANSFERBACK;
 
     /**
      * Returns the algorithm name, used for identifying the algorithm. This string
@@ -409,7 +412,7 @@ class CORE_EXPORT QgsProcessingAlgorithm
      *
      * This method should return a 'pristine' instance of the algorithm class.
      */
-    virtual QgsProcessingAlgorithm *createInstance() const = 0 SIP_FACTORY;
+    virtual QgsProcessingAlgorithm *createInstance() const = 0 SIP_FACTORY SIP_VIRTUALERRORHANDLER( processing_exception_handler );
 
     /**
      * Initializes the algorithm using the specified \a configuration.

tests/src/python/test_qgsprocessingalgrunner.py

@@ -103,7 +103,7 @@ def test_bad_script_dont_crash(self):  # spellok
 
         task = QgsProcessingAlgRunnerTask(CrashingProcessingAlgorithm(), {}, context=context, feedback=feedback)
         self.assertTrue(task.isCanceled())
-        self.assertEqual(feedback._error, 'Error creating algorithm from createInstance()')
+        self.assertIn('name \'ExampleProcessingAlgorithm\' is not defined', feedback._error)
 
 
 if __name__ == '__main__':