qgis · Jul 12, 2017
diff --git a/‎python/core/processing/qgsprocessingalgorithm.sip
Lines changed: 11 additions & 1 deletion b/‎python/core/processing/qgsprocessingalgorithm.sip
Lines changed: 11 additions & 1 deletion
diff --git a/‎python/plugins/processing/algs/qgis/AddTableField.py
Lines changed: 1 addition & 6 deletions b/‎python/plugins/processing/algs/qgis/AddTableField.py
Lines changed: 1 addition & 6 deletions
@@ -392,14 +392,21 @@ class QgsProcessingAlgorithm
 .. seealso:: addOutput()
 %End
 
-    bool addParameter( QgsProcessingParameterDefinition *parameterDefinition /Transfer/ );
+    bool addParameter( QgsProcessingParameterDefinition *parameterDefinition /Transfer/, bool createOutput = true );
 %Docstring
  Adds a parameter ``definition`` to the algorithm. Ownership of the definition is transferred to the algorithm.
  Returns true if parameter could be successfully added, or false if the parameter could not be added (e.g.
  as a result of a duplicate name).
 
  This should usually be called from a subclass' initAlgorithm() implementation.
 
+ If the ``createOutput`` argument is true, then a corresponding output definition will also be created
+ (and added to the algorithm) where appropriate. E.g. when adding a QgsProcessingParameterVectorDestination
+ and ``createOutput`` is true, then a QgsProcessingOutputVectorLayer output will be created and
+ added to the algorithm. There is no need to call addOutput() to manually add a corresponding output
+ for this vector. If ``createOutput`` is false then this automatic output creation will not
+ occur.
+
 .. seealso:: initAlgorithm()
 .. seealso:: addOutput()
  :rtype: bool
@@ -419,6 +426,9 @@ class QgsProcessingAlgorithm
 
  This should usually be called from a subclass' initAlgorithm() implementation.
 
+ Note that in some cases output creation can be automatically performed when calling addParameter().
+ See the notes in addParameter() for a description of when this occurs.
+
 .. seealso:: addParameter()
 .. seealso:: initAlgorithm()
  :rtype: bool
 
@@ -27,16 +27,12 @@
 
 from qgis.PyQt.QtCore import QVariant
 from qgis.core import (QgsField,
-                       QgsFeature,
                        QgsFeatureSink,
-                       QgsApplication,
-                       QgsProcessingUtils,
                        QgsProcessingParameterFeatureSource,
                        QgsProcessingParameterString,
                        QgsProcessingParameterNumber,
                        QgsProcessingParameterEnum,
-                       QgsProcessingParameterFeatureSink,
-                       QgsProcessingOutputVectorLayer)
+                       QgsProcessingParameterFeatureSink)
 from processing.algs.qgis.QgisAlgorithm import QgisAlgorithm
 
 
@@ -73,7 +69,6 @@ def initAlgorithm(self, config=None):
         self.addParameter(QgsProcessingParameterNumber(self.FIELD_PRECISION,
                                                        self.tr('Field precision'), QgsProcessingParameterNumber.Integer, 0, False, 0, 10))
         self.addParameter(QgsProcessingParameterFeatureSink(self.OUTPUT_LAYER, self.tr('Added')))
-        self.addOutput(QgsProcessingOutputVectorLayer(self.OUTPUT_LAYER, self.tr('Added')))
 
     def name(self):
         return 'addfieldtoattributestable'