diff --git a/python/plugins/processing/algs/qgis/scripts/Frequency_analysis.py b/python/plugins/processing/algs/qgis/scripts/Frequency_analysis.py
index 4f4954e8d1d..1bd4917d15e 100644
--- a/python/plugins/processing/algs/qgis/scripts/Frequency_analysis.py
+++ b/python/plugins/processing/algs/qgis/scripts/Frequency_analysis.py
@@ -1,8 +1,14 @@
 ##Table=group
-##Input=vector
-##Fields=Field Input
+
+#inputs
+
+##Input=source
+##Fields=field Input
 ##Frequency=output table
 
+#outputs
+
+
 from processing.tools.vector import TableWriter
 from collections import defaultdict
 from qgis.core import QgsProcessingUtils
diff --git a/python/plugins/processing/algs/qgis/scripts/Keep_n_biggest_parts.py b/python/plugins/processing/algs/qgis/scripts/Keep_n_biggest_parts.py
index 12a32266e54..68b703460ef 100644
--- a/python/plugins/processing/algs/qgis/scripts/Keep_n_biggest_parts.py
+++ b/python/plugins/processing/algs/qgis/scripts/Keep_n_biggest_parts.py
@@ -19,14 +19,12 @@ if To_keep < 1:
     feedback.pushInfo("'To keep' value has been modified to be at least 1.")
     To_keep = 1
 
-
-source = self.parameterAsSource(parameters, 'Polygons', context)
-count = source.featureCount()
+count = Polygons.featureCount()
 (sink, Biggest_parts) = self.parameterAsSink(parameters, 'Biggest parts', context,
-                                             source.fields(), QgsWkbTypes.MultiPolygon, source.sourceCrs())
+                                             Polygons.fields(), QgsWkbTypes.MultiPolygon, Polygons.sourceCrs())
 
 
-for n, feat in enumerate(source.getFeatures()):
+for n, feat in enumerate(Polygons.getFeatures()):
     if feedback.isCanceled():
         break
     feedback.setProgress(int(100 * n / count))
diff --git a/python/plugins/processing/algs/qgis/scripts/Number_of_unique_values_in_classes.py b/python/plugins/processing/algs/qgis/scripts/Number_of_unique_values_in_classes.py
index 513a306d821..6e3b6d2d784 100644
--- a/python/plugins/processing/algs/qgis/scripts/Number_of_unique_values_in_classes.py
+++ b/python/plugins/processing/algs/qgis/scripts/Number_of_unique_values_in_classes.py
@@ -1,25 +1,36 @@
 ##Vector table tools=group
-##input=vector
+
+# inputs
+
+
+##input=source
 ##class_field=field input
 ##value_field=field input
-##N_unique_values=output vector
+##N_unique_values=sink
+
+#outputs
+##N_unique_values=output outputVector
 
 from qgis.PyQt.QtCore import QVariant
 from qgis.core import QgsFeature, QgsField, QgsProcessingUtils
 
-layer = QgsProcessingUtils.mapLayerFromString(input, context)
-fields = layer.fields()
+fields = input.fields()
 fields.append(QgsField('UNIQ_COUNT', QVariant.Int))
-writer, writer_dest = QgsProcessingUtils.createFeatureSink(N_unique_values, context, fields, layer.wkbType(), layer.crs())
 
-class_field_index = layer.fields().lookupField(class_field)
-value_field_index = layer.fields().lookupField(value_field)
+(sink, N_unique_values) = self.parameterAsSink(parameters, 'N_unique_values', context,
+                                               fields, input.wkbType(), input.sourceCrs())
+
+
+class_field_index = input.fields().lookupField(class_field)
+value_field_index = input.fields().lookupField(value_field)
 
 outFeat = QgsFeature()
 classes = {}
-feats = QgsProcessingUtils.getFeatures(layer, context)
-nFeat = QgsProcessingUtils.featureCount(layer, context)
+feats = input.getFeatures()
+nFeat = input.featureCount()
 for n, inFeat in enumerate(feats):
+    if feedback.isCanceled():
+        break
     feedback.setProgress(int(100 * n / nFeat))
     attrs = inFeat.attributes()
     clazz = attrs[class_field_index]
@@ -29,8 +40,10 @@ for n, inFeat in enumerate(feats):
     if value not in classes[clazz]:
         classes[clazz].append(value)
 
-feats = processing.features(layer)
+feats = input.getFeatures()
 for n, inFeat in enumerate(feats):
+    if feedback.isCanceled():
+        break
     feedback.setProgress(int(100 * n / nFeat))
     inGeom = inFeat.geometry()
     outFeat.setGeometry(inGeom)
@@ -38,6 +51,4 @@ for n, inFeat in enumerate(feats):
     clazz = attrs[class_field_index]
     attrs.append(len(classes[clazz]))
     outFeat.setAttributes(attrs)
-    writer.addFeature(outFeat)
-
-del writer
+    sink.addFeature(outFeat)
diff --git a/python/plugins/processing/script/ScriptAlgorithm.py b/python/plugins/processing/script/ScriptAlgorithm.py
index 5cf7eaa563a..40b253403a2 100644
--- a/python/plugins/processing/script/ScriptAlgorithm.py
+++ b/python/plugins/processing/script/ScriptAlgorithm.py
@@ -181,16 +181,53 @@ class ScriptAlgorithm(QgsProcessingAlgorithm):
         ns['scriptDescriptionFile'] = self.descriptionFile
 
         for param in self.parameterDefinitions():
-            ns[param.name()] = parameters[param.name()]
+            method = None
+            if param.type() == "boolean":
+                method = self.parameterAsBool
+            elif param.type() == "crs":
+                method = self.parameterAsCrs
+            elif param.type() == "layer":
+                method = self.parameterAsLayer
+            elif param.type() == "extent":
+                method = self.parameterAsExtent
+            elif param.type() == "point":
+                method = self.parameterAsPoint
+            elif param.type() == "file":
+                method = self.parameterAsFile
+            elif param.type() == "matrix":
+                method = self.parameterAsMatrix
+            elif param.type() == "multilayer":
+                method = self.parameterAsLayerList
+            elif param.type() == "number":
+                method = self.parameterAsDouble
+            elif param.type() == "range":
+                method = self.parameterAsRange
+            elif param.type() == "raster":
+                method = self.parameterAsRasterLayer
+            elif param.type() == "enum":
+                method = self.parameterAsEnum
+            elif param.type() == "string":
+                method = self.parameterAsString
+            elif param.type() == "expression":
+                method = self.parameterAsString
+            elif param.type() == "vector":
+                method = self.parameterAsVectorLayer
+            elif param.type() == "field":
+                method = self.parameterAsString
+            elif param.type() == "source":
+                method = self.parameterAsSource
+
+            if method:
+                ns[param.name()] = method(parameters, param.name(), context)
+
+        for out in self.outputDefinitions():
+            ns[out.name()] = None
 
         ns['self'] = self
         ns['parameters'] = parameters
         ns['feedback'] = feedback
         ns['context'] = context
 
-#        for out in self.outputDefinitions():
-#            ns[out.name()] = out.value
-
         variables = re.findall('@[a-zA-Z0-9_]*', self.script)
         script = 'import processing\n'
         script += self.script