Analysis of Classes without Constructors (bug 675581)

There are a number of classes in the GNOME APIs that are not intended for direct creation. The issue is there is not an accurate way to generically determine this. GI bindings are general and expose everything they can, this makes a number of classes available which crash when an attempt is made to instantiate them. However, we can look at classes which do not explicitly implement constructors as a hint. The following script and table attempts some analysis as to what classes do not have constructors and why.

Script Used to Generate Initial Table

This script iterates a number of Python GI imported namespaces and looks for GObject.Object based classes which do not provide a public constructor.

   1 import inspect
   2 import gi
   3 from gi.repository import GObject, Gtk, Gdk, GdkPixbuf, Gio
   4 
   5 repo = gi.gi.Repository.get_default()
   6 modules = dict(GObject=GObject,
   7                Gtk=Gtk, Gdk=Gdk,
   8                GdkPixbuf=GdkPixbuf,
   9                Gio=Gio)
  10 
  11 print("||'''Name'''||'''Bug'''||'''Alternative'''||'''Reason'''||")
  12 for modname, mod in sorted(modules.items()):
  13     for name in dir(mod):
  14         obj = getattr(mod, name)
  15         if not inspect.isclass(obj) or not issubclass(obj, GObject.Object):
  16             continue
  17         info = repo.find_by_name(modname, name)
  18         if isinstance(info, (gi.types.ObjectInfo, )) and not info.get_abstract():
  19             if not any(meth.is_constructor() for meth in info.get_methods()):
  20                 print('||`%s.%s` ||  ||  ||  ||' % (modname, name))

Classes without Constructors

Name

Bug

Alternative

Reason

GObject.Binding

675581

GObject.Object.bind_property(...)

Non-generic semantics, requires construct only arguments.

GObject.InitiallyUnowned

[1]

Gdk.Display

Gdk.Display.get_default()

Singleton

Gdk.DisplayManager

Gdk.Display.get_default() or Gdk.Display.get()

Singleton

Gdk.DragContext

Gdk.drag_begin()

[1]

Gdk.Keymap

Gdk.Keymap.get_default()

Singleton

Gdk.Screen

687792

Screen.get_default()

Singleton

Gdk.Visual

[1]

GdkPixbuf.PixbufAnimationIter

[1]

GdkPixbuf.PixbufSimpleAnimIter

[1]

Gio.ApplicationCommandLine

[1] (Usually created by GApplication)

Gio.DBusActionGroup

Gio.DBusActionGroup.get()

[1]

Gio.DBusMenuModel

Gio.DBusMenuModel.get()

[1]

Gio.DBusMethodInvocation

[1] Received as argument to the handle_method_call() function

Gio.FileEnumerator

Gio.File.enumerate_children()

[1]

Gio.FileIOStream

unknown

Gio.FileInputStream

unknown

Gio.FileOutputStream

unknown

Gio.MemoryOutputStream

unknown

Gio.ProxyAddressEnumerator

Gio.SocketConnectable.enumerate()

[1]

Gio.Resolver

Gio.Resolver

[1]

Gio.SocketConnection

unknown

Gio.TcpConnection

unknown

Gio.TlsInteraction

unknown

Gio.UnixConnection

unknown

Gio.Vfs

Gio.Vfs.get_default() or Gio.Vfs.get_local()

Singleton

Gio.VolumeMonitor

647731

Gio.VolumeMonitor.get()

Singleton

Gtk.AccelMap

Gtk.AccelMap.get()

[1]

Gtk.Accessible

unknown

Gtk.CellAreaContext

Gtk.CellAreaClass.create_context()

[1]

Gtk.Clipboard

Gtk.Clipboard.get()

[1]

Gtk.FileChooserDialog

Generic creation works and is necessary. Constructor skipped do to variadic arguments.

Gtk.MessageDialog

Generic creation works and is necessary. Constructor skipped do to variadic arguments.

Gtk.NumerableIcon

Works. gtk_numerable_icon_new marked as function not constructor do to annotation problem?

Gtk.PrintContext

[1] Gtk.PrintContext objects gets passed to the ::begin-print, ::end-print, ::request-page-setup and ::draw-page signals on the Gtk.PrintOperation.

Gtk.RecentChooserDialog

Generic creation works and is necessary. Constructor skipped do to variadic arguments.

Gtk.Settings

Gtk.Settings.get_default()

[1]

Gtk.ThemingEngine

[1]

Gtk.Tooltip

[1] Instance passed to "query-tooltip" signal handler

Gtk.TreeModelFilter

Gtk.TreeModel.filter_new()

[1]

Xkl.Engine

680202

Xkl.Engine.get_instance(display)

[1] - Generic creation works but the class might not be necessary in Python.

Projects/PyGObject/Analysis/Bug675581 (last edited 2013-11-23 00:13:40 by WilliamJonMcCann)