AutoPropertyObject: support abstract and class properties (PR #8393)

Closes #8294
Fixes #8652
Closes #8658

Properties and methods within classes can now be marked as abstract in NVDA. These classes will raise an error if instantiated.
See PR #8393 for full description.

source/NVDAObjects/__init__.py

@@ -6,7 +6,8 @@
 #See the file COPYING for more details.
 
 """Module that contains the base NVDA object type"""
-from new import instancemethod
+
+from six import with_metaclass
 import time
 import re
 import weakref
@@ -145,7 +146,7 @@ def clearDynamicClassCache(cls):
 		"""
 		cls._dynamicClassCache.clear()
 
-class NVDAObject(documentBase.TextContainerObject,baseObject.ScriptableObject):
+class NVDAObject(with_metaclass(DynamicNVDAObjectType, documentBase.TextContainerObject,baseObject.ScriptableObject)):
 	"""NVDA's representation of a single control/widget.
 	Every widget, regardless of how it is exposed by an application or the operating system, is represented by a single NVDAObject instance.
 	This allows NVDA to work with all widgets in a uniform way.
@@ -169,7 +170,6 @@ class NVDAObject(documentBase.TextContainerObject,baseObject.ScriptableObject):
 	An L{AppModule} can also choose overlay classes for an instance using the L{AppModule.chooseNVDAObjectOverlayClasses} method.
 	"""
 
-	__metaclass__=DynamicNVDAObjectType
 	cachePropertiesByDefault = True
 
 	#: The TextInfo class this object should use to provide access to text.

source/baseObject.py

@@ -9,31 +9,44 @@
 
 import weakref
 from logHandler import log
+from abc import ABCMeta, abstractproperty
+from six import with_metaclass
 
 class Getter(object):
 
-	def __init__(self,fget):
+	def __init__(self,fget, abstract=False):
 		self.fget=fget
+		if abstract:
+			if isinstance(fget, classmethod):
+				log.warning("Abstract class properties are not supported.")
+				self._abstract = False
+			else:
+				self._abstract = self.__isabstractmethod__=abstract
 
 	def __get__(self,instance,owner):
-		if not instance:
+		if isinstance(self.fget, classmethod):
+			return self.fget.__get__(instance, owner)()
+		elif not instance:
 			return self
 		return self.fget(instance)
 
 	def setter(self,func):
-		return property(fget=self._func,fset=func)
+		return (abstractproperty if self._abstract else property)(fget=self.fget,fset=func)
 
 	def deleter(self,func):
-		return property(fget=self._func,fdel=func)
+		return (abstractproperty if self._abstract else property)(fget=self.fget,fdel=func)
 
 class CachingGetter(Getter):
 
 	def __get__(self, instance, owner):
-		if not instance:
+		if isinstance(self.fget, classmethod):
+			log.warning("Class properties do not support caching")
+			return self.fget.__get__(instance, owner)()
+		elif not instance:
 			return self
 		return instance._getPropertyViaCache(self.fget)
 
-class AutoPropertyType(type):
+class AutoPropertyType(ABCMeta):
 
 	def __init__(self,name,bases,dict):
 		super(AutoPropertyType,self).__init__(name,bases,dict)
@@ -44,6 +57,10 @@ def __init__(self,name,bases,dict):
 		except KeyError:
 			cacheByDefault=any(getattr(base, "cachePropertiesByDefault", False) for base in bases)
 
+		# Create a set containing properties that are marked as abstract.
+		newAbstractProps=set()
+		# Create a set containing properties that were, but are no longer abstract.
+		oldAbstractProps=set()
 		# given _get_myVal, _set_myVal, and _del_myVal: "myVal" would be output 3 times
 		# use a set comprehension to ensure unique values, "myVal" only needs to occur once.
 		props={x[5:] for x in dict.keys() if x[0:5] in ('_get_','_set_','_del_')}
@@ -70,24 +87,39 @@ def __init__(self,name,bases,dict):
 					if cache is not None:
 						break
 				else:
-					cache=cacheByDefault
+					cache=cacheByDefault if not isinstance(g, classmethod) else False
 
-			if g and not s and not d:
-				setattr(self,x,(CachingGetter if cache else Getter)(g))
+			abstract=dict.get('_abstract_%s'%x,False)
+			if g and not (s or d):
+				attr = (CachingGetter if cache else Getter)(g,abstract)
 			else:
-				setattr(self,x,property(fget=g,fset=s,fdel=d))
-
-class AutoPropertyObject(object):
-	"""A class that dynamicly supports properties, by looking up _get_* and _set_* methods at runtime.
+				attr = (abstractproperty if abstract else property)(fget=g,fset=s,fdel=d)
+			if abstract:
+				newAbstractProps.add(x)
+			elif x in self.__abstractmethods__:
+				oldAbstractProps.add(x)
+			setattr(self,x, attr)
+
+		if newAbstractProps or oldAbstractProps:
+			# The __abstractmethods__ set is frozen, therefore we ought to override it.
+			self.__abstractmethods__=(self.__abstractmethods__|newAbstractProps)-oldAbstractProps
+
+class AutoPropertyObject(with_metaclass(AutoPropertyType, object)):
+	"""A class that dynamically supports properties, by looking up _get_*, _set_*, and _del_* methods at runtime.
 	_get_x will make property x with a getter (you can get its value).
 	_set_x will make a property x with a setter (you can set its value).
+	_del_x will make a property x with a deleter that is executed when deleting its value.
 	If there is a _get_x but no _set_x then setting x will override the property completely.
 	Properties can also be cached for the duration of one core pump cycle.
-	This is useful if the same property is likely to be fetched multiple times in one cycle. For example, several NVDAObject properties are fetched by both braille and speech.
-	Setting _cache_x to C{True} specifies that x should be cached. Setting it to C{False} specifies that it should not be cached.
+	This is useful if the same property is likely to be fetched multiple times in one cycle.
+	For example, several NVDAObject properties are fetched by both braille and speech.
+	Setting _cache_x to C{True} specifies that x should be cached.
+	Setting it to C{False} specifies that it should not be cached.
 	If _cache_x is not set, L{cachePropertiesByDefault} is used.
+	Properties can also be made abstract.
+	Setting _abstract_x to C{True} specifies that x should be abstract.
+	Setting it to C{False} specifies that it should not be abstract.
 	"""
-	__metaclass__=AutoPropertyType
 
 	#: Tracks the instances of this class; used by L{invalidateCaches}.
 	#: @type: weakref.WeakKeyDictionary
@@ -153,7 +185,7 @@ def __new__(meta, name, bases, dict):
 			setattr(cls, gesturesDictName, gestures)
 		return cls
 
-class ScriptableObject(AutoPropertyObject):
+class ScriptableObject(with_metaclass(ScriptableType, AutoPropertyObject)):
 	"""A class that implements NVDA's scripting interface.
 	Input gestures are bound to scripts such that the script will be executed when the appropriate input gesture is received.
 	Scripts are methods named with a prefix of C{script_}; e.g. C{script_foo}.
@@ -168,8 +200,6 @@ class ScriptableObject(AutoPropertyObject):
 	@type scriptCategory: basestring
 	"""
 
-	__metaclass__ = ScriptableType
-
 	def __init__(self):
 		#: Maps input gestures to script functions.
 		#: @type: dict

source/browseMode.py

@@ -34,6 +34,8 @@
 import api
 import gui.guiHelper
 from NVDAObjects import NVDAObject
+from abc import ABCMeta, abstractmethod
+from six import with_metaclass
 
 REASON_QUICKNAV = "quickNav"
 
@@ -91,7 +93,7 @@ def mergeQuickNavItemIterators(iterators,direction="next"):
 			continue
 		curValues.append((it,newVal))
 
-class QuickNavItem(object):
+class QuickNavItem(with_metaclass(ABCMeta, object)):
 	""" Emitted by L{BrowseModeTreeInterceptor._iterNodesByType}, this represents one of many positions in a browse mode document, based on the type of item being searched for (e.g. link, heading, table etc)."""  
 
 	itemType=None #: The type of items searched for (e.g. link, heading, table etc) 
@@ -108,6 +110,7 @@ def __init__(self,itemType,document):
 		self.itemType=itemType
 		self.document=document
 
+	@abstractmethod
 	def isChild(self,parent):
 		"""
 		Is this item a child of the given parent?
@@ -119,6 +122,7 @@ def isChild(self,parent):
 		"""
 		raise NotImplementedError
 
+	@abstractmethod
 	def report(self,readUnit=None):
 		"""
 		Reports the contents of this item.
@@ -127,6 +131,7 @@ def report(self,readUnit=None):
 		"""
 		raise NotImplementedError
 
+	@abstractmethod
 	def moveTo(self):
 		"""
 		Moves the browse mode caret or focus to this item.

source/contentRecog/__init__.py

@@ -15,9 +15,11 @@
 
 from collections import namedtuple
 import textInfos.offsets
+from abc import ABCMeta, abstractmethod
+from six import with_metaclass
 from locationHelper import RectLTWH
 
-class ContentRecognizer(object):
+class ContentRecognizer(with_metaclass(ABCMeta, object)):
 	"""Implementation of a content recognizer.
 	"""
 
@@ -33,6 +35,7 @@ def getResizeFactor(self, width, height):
 		"""
 		return 1
 
+	@abstractmethod
 	def recognize(self, pixels, imageInfo, onResult):
 		"""Asynchronously recognize content from an image.
 		This method should not block.
@@ -51,6 +54,7 @@ def recognize(self, pixels, imageInfo, onResult):
 		"""
 		raise NotImplementedError
 
+	@abstractmethod
 	def cancel(self):
 		"""Cancel the recognition in progress (if any).
 		"""
@@ -125,7 +129,7 @@ def convertHeightToScreen(self, height):
 		"""
 		return int(height / self.resizeFactor)
 
-class RecognitionResult(object):
+class RecognitionResult(with_metaclass(ABCMeta, object)):
 	"""Provides access to the result of recognition by a recognizer.
 	The result is textual, but to facilitate navigation by word, line, etc.
 	and to allow for retrieval of screen coordinates within the text,
@@ -134,6 +138,7 @@ class RecognitionResult(object):
 	Most implementers should use one of the subclasses provided in this module.
 	"""
 
+	@abstractmethod
 	def makeTextInfo(self, obj, position):
 		"""Make a TextInfo within the recognition result text at the requested position.
 		@param obj: The object to return for the C{obj} property of the TextInfo.

source/gui/accPropServer.py

@@ -10,14 +10,16 @@
 from  comtypes.automation import VT_EMPTY
 from  comtypes import COMObject
 from comInterfaces.Accessibility import IAccPropServer
+from abc import ABCMeta, abstractmethod
+from six import with_metaclass
 import weakref
 
-class IAccPropServer_Impl(COMObject):
+class IAccPropServer_Impl(with_metaclass(ABCMeta, COMObject)):
 	"""Base class for implementing a COM interface for AccPropServer.
 	Please override the _GetPropValue method, not GetPropValue.
 	GetPropValue wraps _getPropValue to catch and log exceptions (Which for some reason NVDA's logger misses when they occur in GetPropValue).
 	"""
-	
+
 	_com_interfaces_ = [
 		IAccPropServer
 	]
@@ -31,6 +33,7 @@ def __init__(self, control, *args, **kwargs):
 		self.control = weakref.ref(control)
 		super(IAccPropServer_Impl, self).__init__(*args, **kwargs)
 
+	@abstractmethod
 	def _getPropValue(self, pIDString, dwIDStringLen, idProp):
 		"""use this method to implement GetPropValue. It  is wrapped by the callback GetPropValue to handle exceptions.
 		For instructions on implementing accPropServers, see https://msdn.microsoft.com/en-us/library/windows/desktop/dd373681(v=vs.85).aspx .

source/gui/guiHelper.py

@@ -44,6 +44,7 @@ def __init__(self,parent):
 """
 import wx
 from wx.lib import scrolledpanel
+from abc import ABCMeta
 
 #: border space to be used around all controls in dialogs
 BORDER_FOR_DIALOGS=10
@@ -301,3 +302,7 @@ def addDialogDismissButtons(self, buttons):
 		self.dialogDismissButtonsAdded = True
 		return buttons
 
+class SIPABCMeta(wx.siplib.wrappertype, ABCMeta):
+	"""Meta class to be used for wx subclasses with abstract methods."""
+	pass
+

source/gui/settingsDialogs.py

@@ -5,6 +5,8 @@
 #This file is covered by the GNU General Public License.
 #See the file COPYING for more details.
 
+from abc import abstractmethod
+from six import with_metaclass
 import glob
 import os
 import copy
@@ -49,7 +51,7 @@
 import keyLabels
 from dpiScalingHelper import DpiScalingHelperMixin
 
-class SettingsDialog(wx.Dialog, DpiScalingHelperMixin):
+class SettingsDialog(with_metaclass(guiHelper.SIPABCMeta, wx.Dialog, DpiScalingHelperMixin)):
 	"""A settings dialog.
 	A settings dialog consists of one or more settings controls and OK and Cancel buttons and an optional Apply button.
 	Action may be taken in response to the OK, Cancel or Apply buttons.
@@ -161,6 +163,7 @@ def _enterActivatesOk_ctrlSActivatesApply(self, evt):
 		else:
 			evt.Skip()
 
+	@abstractmethod
 	def makeSettings(self, sizer):
 		"""Populate the dialog with settings controls.
 		Subclasses must override this method.
@@ -205,7 +208,7 @@ def onApply(self, evt):
 # redo the layout in whatever way makes sense for their particular content.
 _RWLayoutNeededEvent, EVT_RW_LAYOUT_NEEDED = wx.lib.newevent.NewCommandEvent()
 
-class SettingsPanel(wx.Panel, DpiScalingHelperMixin):
+class SettingsPanel(with_metaclass(guiHelper.SIPABCMeta, wx.Panel, DpiScalingHelperMixin)):
 	"""A settings panel, to be used in a multi category settings dialog.
 	A settings panel consists of one or more settings controls.
 	Action may be taken in response to the parent dialog's OK or Cancel buttons.
@@ -243,6 +246,7 @@ def __init__(self, parent):
 		if gui._isDebug():
 			log.debug("Loading %s took %.2f seconds"%(self.__class__.__name__, time.time() - startTime))
 
+	@abstractmethod
 	def makeSettings(self, sizer):
 		"""Populate the panel with settings controls.
 		Subclasses must override this method.
@@ -264,6 +268,7 @@ def onPanelDeactivated(self):
 		"""
 		self.Hide()
 
+	@abstractmethod
 	def onSave(self):
 		"""Take action in response to the parent's dialog OK or apply button being pressed.
 		Sub-classes should override this method.

source/inputCore.py

@@ -64,6 +64,7 @@ class InputGesture(baseObject.AutoPropertyObject):
 	#: @type: bool
 	reportInInputHelp=True
 
+	_abstract_identifiers = True
 	def _get_identifiers(self):
 		"""The identifier(s) which will be used in input gesture maps to represent this gesture.
 		These identifiers will be normalized and looked up in order until a match is found.