[FEATURE][needs-docs] Add new @alg decorator for nicer python processing scripts. (#8586)

@alg()
@alg.help()
@alg.input()
@alg.output()

Author: NathanW2

python/CMakeLists.txt

@@ -66,6 +66,7 @@ ENDIF ()
 ADD_SUBDIRECTORY(PyQt)
 ADD_SUBDIRECTORY(ext-libs)
 ADD_SUBDIRECTORY(testing)
+ADD_SUBDIRECTORY(processing)
 
 INCLUDE_DIRECTORIES(SYSTEM
   ${PYTHON_INCLUDE_PATH}

python/plugins/processing/script/DeleteScriptAction.py

@@ -52,7 +52,7 @@ def execute(self):
                                      QMessageBox.Yes | QMessageBox.No,
                                      QMessageBox.No)
         if reply == QMessageBox.Yes:
-            filePath = ScriptUtils.findAlgorithmSource(self.itemData.__class__.__name__)
+            filePath = ScriptUtils.findAlgorithmSource(self.itemData.name())
             if filePath is not None:
                 os.remove(filePath)
                 QgsApplication.processingRegistry().providerById("script").refreshAlgorithms()

python/plugins/processing/script/EditScriptAction.py

@@ -27,7 +27,7 @@
 
 import inspect
 
-from qgis.core import QgsProcessingAlgorithm
+from qgis.core import QgsProcessingAlgorithm, QgsMessageLog
 from qgis.utils import iface
 from qgis.PyQt.QtCore import QCoreApplication
 from qgis.PyQt.QtWidgets import QMessageBox
@@ -47,7 +47,7 @@ def isEnabled(self):
         return isinstance(self.itemData, QgsProcessingAlgorithm) and self.itemData.provider().id() == "script"
 
     def execute(self):
-        filePath = ScriptUtils.findAlgorithmSource(self.itemData.__class__.__name__)
+        filePath = ScriptUtils.findAlgorithmSource(self.itemData.name())
         if filePath is not None:
             dlg = ScriptEditorDialog(filePath, iface.mainWindow())
             dlg.show()

python/plugins/processing/script/ScriptEditorDialog.py

@@ -44,6 +44,7 @@
                        QgsProcessingAlgorithm,
                        QgsProcessingFeatureBasedAlgorithm)
 from qgis.utils import iface, OverrideCursor
+from qgis.processing import alg as algfactory
 
 from processing.gui.AlgorithmDialog import AlgorithmDialog
 from processing.script import ScriptUtils
@@ -222,9 +223,9 @@ def setHasChanged(self, hasChanged):
         self.update_dialog_title()
 
     def runAlgorithm(self):
-        d = {}
+        _locals = {}
         try:
-            exec(self.editor.text(), d)
+            exec(self.editor.text(), _locals)
         except Exception as e:
             error = QgsError(traceback.format_exc(), "Processing")
             QgsErrorDialog.show(error,
@@ -233,10 +234,13 @@ def runAlgorithm(self):
             return
 
         alg = None
-        for k, v in d.items():
-            if inspect.isclass(v) and issubclass(v, (QgsProcessingAlgorithm, QgsProcessingFeatureBasedAlgorithm)) and v.__name__ not in ("QgsProcessingAlgorithm", "QgsProcessingFeatureBasedAlgorithm"):
-                alg = v()
-                break
+        try:
+            alg = algfactory.instances.pop().createInstance()
+        except IndexError:
+            for name, attr in _locals.items():
+                if inspect.isclass(attr) and issubclass(attr, (QgsProcessingAlgorithm, QgsProcessingFeatureBasedAlgorithm)) and attr.__name__ not in ("QgsProcessingAlgorithm", "QgsProcessingFeatureBasedAlgorithm"):
+                    alg = attr()
+                    break
 
         if alg is None:
             QMessageBox.warning(self,

python/plugins/processing/script/ScriptUtils.py

@@ -25,6 +25,7 @@
 
 __revision__ = '$Format:%H$'
 
+from qgis.processing import alg as algfactory
 import os
 import inspect
 import importlib
@@ -66,20 +67,26 @@ def loadAlgorithm(moduleName, filePath):
         spec = importlib.util.spec_from_file_location(moduleName, filePath)
         module = importlib.util.module_from_spec(spec)
         spec.loader.exec_module(module)
-        for x in dir(module):
-            obj = getattr(module, x)
-            if inspect.isclass(obj) and issubclass(obj, (QgsProcessingAlgorithm, QgsProcessingFeatureBasedAlgorithm)) and obj.__name__ not in ("QgsProcessingAlgorithm", "QgsProcessingFeatureBasedAlgorithm"):
-                scriptsRegistry[x] = filePath
-                return obj()
+        try:
+            alg = algfactory.instances.pop().createInstance()
+            scriptsRegistry[alg.name()] = filePath
+            return alg
+        except IndexError:
+            for x in dir(module):
+                obj = getattr(module, x)
+                if inspect.isclass(obj) and issubclass(obj, (QgsProcessingAlgorithm, QgsProcessingFeatureBasedAlgorithm)) and obj.__name__ not in ("QgsProcessingAlgorithm", "QgsProcessingFeatureBasedAlgorithm"):
+                    o = obj()
+                    scriptsRegistry[o.name()] = filePath
+                    return o
     except ImportError as e:
         QgsMessageLog.logMessage(QCoreApplication.translate("ScriptUtils", "Could not import script algorithm '{}' from '{}'\n{}").format(moduleName, filePath, str(e)),
                                  QCoreApplication.translate("ScriptUtils", "Processing"),
                                  Qgis.Critical)
 
 
-def findAlgorithmSource(className):
+def findAlgorithmSource(name):
     global scriptsRegistry
     try:
-        return scriptsRegistry[className]
+        return scriptsRegistry[name]
     except:
         return None

python/processing/CMakeLists.txt

@@ -0,0 +1,25 @@
+# See ../CMakeLists.txt for info on staged-plugins* and clean-staged-plugins targets
+
+SET(QGIS_PYTHON_DIR ${PYTHON_SITE_PACKAGES_DIR}/qgis)
+SET (PYTHON_OUTPUT_DIRECTORY ${QGIS_OUTPUT_DIRECTORY}/python)
+SET (NAME processing)
+
+SET(PY_FILES
+  __init__.py
+  algfactory.py
+)
+
+FILE (MAKE_DIRECTORY ${QGIS_PYTHON_OUTPUT_DIRECTORY}/${NAME})
+INSTALL(FILES ${PY_FILES} DESTINATION "${QGIS_PYTHON_DIR}/${NAME}")
+
+ADD_CUSTOM_TARGET(py${NAME} ALL)
+# stage to output to make available when QGIS is run from build directory
+FOREACH(pyfile ${PY_FILES})
+  ADD_CUSTOM_COMMAND(TARGET py${NAME}
+    POST_BUILD
+    COMMAND ${CMAKE_COMMAND} -E copy ${pyfile} "${QGIS_PYTHON_OUTPUT_DIRECTORY}/${NAME}"
+    WORKING_DIRECTORY ${CMAKE_CURRENT_SOURCE_DIR}
+    DEPENDS ${pyfile}
+  )
+  PY_COMPILE(pyutils "${QGIS_PYTHON_OUTPUT_DIRECTORY}/${NAME}/${pyfile}")
+ENDFOREACH(pyfile)

python/processing/__init__.py

@@ -0,0 +1,28 @@
+# -*- coding: utf-8 -*-
+
+"""
+***************************************************************************
+    __init__.py
+    ---------------------
+    Date                 : November 2018
+    Copyright            : (C) 2018 by Nathan Woodrow
+    Email                : woodrow dot nathan at gmail dot com
+***************************************************************************
+*                                                                         *
+*   This program is free software; you can redistribute it and/or modify  *
+*   it under the terms of the GNU General Public License as published by  *
+*   the Free Software Foundation; either version 2 of the License, or     *
+*   (at your option) any later version.                                   *
+*                                                                         *
+***************************************************************************
+"""
+
+__author__ = 'Nathan Woodrow'
+__date__ = 'November 2018'
+__copyright__ = '(C) 2018, Nathan Woodrow'
+# This will get replaced with a git SHA1 when you do a git archive
+__revision__ = '$Format:%H$'
+
+from .algfactory import ProcessingAlgFactory
+
+alg = ProcessingAlgFactory()