Fix reference cycles due to lambda/partial slots in various dialogs

setup.cfg

@@ -1,6 +1,6 @@
 [flake8]
 max-line-length = 160
-builtins = _,dynamic_property,__,P,I,lopen,icu_lower,icu_upper,icu_title,ngettext
+builtins = _,dynamic_property,__,P,I,lopen,icu_lower,icu_upper,icu_title,ngettext,connect_lambda
 ignore = E12,E203,E22,E231,E241,E401,E402,E731,W391,E722,E741,W504
 
 [yapf]

src/calibre/gui2/dialogs/book_info.py

@@ -2,8 +2,6 @@
 # License: GPLv3 Copyright: 2008, Kovid Goyal <kovid at kovidgoyal.net>
 from __future__ import absolute_import, division, print_function, unicode_literals
 
-from functools import partial
-
 from PyQt5.Qt import (
     QBrush, QCheckBox, QCoreApplication, QDialog, QGridLayout, QHBoxLayout, QIcon,
     QKeySequence, QLabel, QListView, QModelIndex, QPalette, QPixmap, QPushButton,
@@ -40,14 +38,14 @@ class Configure(Dialog):
         h.addWidget(fdo)
         v = QVBoxLayout()
         self.mub = b = QToolButton(self)
-        b.clicked.connect(partial(move_field_up, fdo, self.model))
+        connect_lambda(b.clicked, self, lambda self: move_field_up(fdo, self.model))
         b.setIcon(QIcon(I('arrow-up.png')))
         b.setToolTip(_('Move the selected field up'))
         v.addWidget(b), v.addStretch(10)
         self.mud = b = QToolButton(self)
         b.setIcon(QIcon(I('arrow-down.png')))
         b.setToolTip(_('Move the selected field down'))
-        b.clicked.connect(partial(move_field_down, fdo, self.model))
+        connect_lambda(b.clicked, self, lambda self: move_field_down(fdo, self.model))
         v.addWidget(b)
         h.addLayout(v)
 

src/calibre/gui2/dialogs/confirm_delete_location.py

@@ -4,8 +4,6 @@ __copyright__ = '2008, Kovid Goyal kovid@kovidgoyal.net' \
                 '2010, John Schember <john@nachtimwald.com>'
 __docformat__ = 'restructuredtext en'
 
-from functools import partial
-
 from calibre.gui2.dialogs.confirm_delete_location_ui import Ui_Dialog
 from PyQt5.Qt import QDialog, Qt, QPixmap, QIcon
 
@@ -20,9 +18,9 @@ class Dialog(QDialog, Ui_Dialog):
         self.msg.setText(msg)
         self.name = name
         self.buttonBox.setFocus(Qt.OtherFocusReason)
-        self.button_lib.clicked.connect(partial(self.set_loc, 'lib'))
+        connect_lambda(self.button_lib.clicked, self, lambda self: self.set_loc('lib'))
-        self.button_device.clicked.connect(partial(self.set_loc, 'dev'))
+        connect_lambda(self.button_device.clicked, self, lambda self: self.set_loc('dev'))
-        self.button_both.clicked.connect(partial(self.set_loc, 'both'))
+        connect_lambda(self.button_both.clicked, self, lambda self: self.set_loc('both'))
 
     def set_loc(self, loc):
         self.loc = loc

src/calibre/gui2/dialogs/confirm_merge.py

@@ -6,7 +6,6 @@ from __future__ import (unicode_literals, division, absolute_import,
 __license__ = 'GPL v3'
 __copyright__ = '2015, Kovid Goyal <kovid at kovidgoyal.net>'
 
-from functools import partial
 from PyQt5.Qt import (
     QVBoxLayout, QSplitter, QWidget, QLabel, QCheckBox, QTextBrowser, Qt,
 )
@@ -116,7 +115,7 @@ class ChooseMerge(Dialog):
             l.addWidget(ans)
             prefs_key = ans.prefs_key = 'choose-merge-cb-' + name
             ans.setChecked(gprefs.get(prefs_key, True))
-            ans.stateChanged.connect(partial(self.state_changed, ans), type=Qt.QueuedConnection)
+            connect_lambda(ans.stateChanged, self, lambda self, state: self.state_changed(ans, state), type=Qt.QueuedConnection)
             if tt:
                 ans.setToolTip(tt)
             setattr(self, name, ans)

src/calibre/gui2/dialogs/custom_recipes.py

@@ -561,7 +561,7 @@ class CustomRecipes(Dialog):
         d.l = QVBoxLayout()
         d.setLayout(d.l)
         d.list = QListWidget(d)
-        d.list.doubleClicked.connect(lambda x: d.accept())
+        connect_lambda(d.list.doubleClicked, d, lambda d: d.accept())
         d.l.addWidget(d.list)
         d.bb = QDialogButtonBox(QDialogButtonBox.Ok|QDialogButtonBox.Cancel,
                 Qt.Horizontal, d)

src/calibre/gui2/dialogs/exim.py

@@ -177,10 +177,10 @@ class EximDialog(Dialog):
         l.addWidget(la)
         l.addSpacing(20)
         self.exp_button = b = QPushButton(_('&Export all your calibre data'))
-        b.clicked.connect(partial(self.show_panel, 'export'))
+        connect_lambda(b.clicked, self, lambda self: self.show_panel('export'))
         l.addWidget(b), l.addSpacing(20)
         self.imp_button = b = QPushButton(_('&Import previously exported data'))
-        b.clicked.connect(partial(self.show_panel, 'import'))
+        connect_lambda(b.clicked, self, lambda self: self.show_panel('import'))
         l.addWidget(b), l.addStretch(20)
 
         self.setup_export_panel()

src/calibre/gui2/dialogs/metadata_bulk.py

@@ -494,7 +494,7 @@ class MetadataBulkDialog(QDialog, Ui_MetadataBulkDialog):
         self.initialize_combos()
 
         self.series.currentIndexChanged[int].connect(self.series_changed)
-        self.rating.currentIndexChanged.connect(lambda:self.apply_rating.setChecked(True))
+        connect_lambda(self.rating.currentIndexChanged, self, lambda self:self.apply_rating.setChecked(True))
         self.series.editTextChanged.connect(self.series_changed)
         self.tag_editor_button.clicked.connect(self.tag_editor)
         self.autonumber_series.stateChanged[int].connect(self.auto_number_changed)
@@ -525,7 +525,9 @@ class MetadataBulkDialog(QDialog, Ui_MetadataBulkDialog):
         idx = max(0, self.casing_map.index(prevca))
         self.casing_algorithm.setCurrentIndex(idx)
         self.casing_algorithm.setEnabled(False)
-        self.change_title_to_title_case.toggled.connect(lambda : self.casing_algorithm.setEnabled(self.change_title_to_title_case.isChecked()))
+        connect_lambda(
+            self.change_title_to_title_case.toggled, self,
+            lambda self: self.casing_algorithm.setEnabled(self.change_title_to_title_case.isChecked()))
 
         if len(self.db.custom_field_keys(include_composites=False)) == 0:
             self.central_widget.removeTab(1)

src/calibre/gui2/dialogs/search.py

@@ -212,11 +212,11 @@ def create_date_tab(self, db):
     self.date_human = dh = a(QComboBox(w))
     for val, text in [('today', _('Today')), ('yesterday', _('Yesterday')), ('thismonth', _('This month'))]:
         dh.addItem(text, val)
-    self.date_year.valueChanged.connect(lambda : self.sel_date.setChecked(True))
+    connect_lambda(self.date_year.valueChanged, self, lambda self: self.sel_date.setChecked(True))
-    self.date_month.currentIndexChanged.connect(lambda : self.sel_date.setChecked(True))
+    connect_lambda(self.date_month.currentIndexChanged, self, lambda self: self.sel_date.setChecked(True))
-    self.date_day.valueChanged.connect(lambda : self.sel_date.setChecked(True))
+    connect_lambda(self.date_day.valueChanged, self, lambda self: self.sel_date.setChecked(True))
-    self.date_daysago.valueChanged.connect(lambda : self.sel_daysago.setChecked(True))
+    connect_lambda(self.date_daysago.valueChanged, self, lambda self: self.sel_daysago.setChecked(True))
-    self.date_human.currentIndexChanged.connect(lambda : self.sel_human.setChecked(True))
+    connect_lambda(self.date_human.currentIndexChanged, self, lambda self: self.sel_human.setChecked(True))
     self.sel_date.setChecked(True)
     h.addStretch(10)
 

src/calibre/gui2/dialogs/tag_editor.py

@@ -1,8 +1,6 @@
 __license__   = 'GPL v3'
 __copyright__ = '2008, Kovid Goyal <kovid at kovidgoyal.net>'
 
-from functools import partial
-
 from PyQt5.Qt import Qt, QDialog, QAbstractItemView
 
 from calibre.gui2.dialogs.tag_editor_ui import Ui_TagEditor
@@ -67,19 +65,18 @@ class TagEditor(QDialog, Ui_TagEditor):
             if tag not in q:
                 self.available_tags.addItem(tag)
 
-        self.apply_button.clicked.connect(lambda: self.apply_tags())
+        connect_lambda(self.apply_button.clicked, self, lambda self: self.apply_tags())
-        self.unapply_button.clicked.connect(lambda: self.unapply_tags())
+        connect_lambda(self.unapply_button.clicked, self, lambda self: self.unapply_tags())
         self.add_tag_button.clicked.connect(self.add_tag)
-        self.delete_button.clicked.connect(lambda: self.delete_tags())
+        connect_lambda(self.delete_button.clicked, self, lambda self: self.delete_tags())
         self.add_tag_input.returnPressed[()].connect(self.add_tag)
         # add the handlers for the filter input fields
-        self.available_filter_input.textChanged.connect(self.filter_tags)
+        connect_lambda(self.available_filter_input.textChanged, self, lambda self, text: self.filter_tags(text))
-        self.applied_filter_input.textChanged.connect(partial(self.filter_tags, which='applied_tags'))
+        connect_lambda(self.applied_filter_input.textChanged, self, lambda self, text: self.filter_tags(text, which='applied_tags'))
 
         # Restore the focus to the last input box used (typed into)
-        self.add_tag_input.textChanged.connect(partial(self.edit_box_changed, which="add_tag_input"))
+        for x in ('add_tag_input', 'available_filter_input', 'applied_filter_input'):
-        self.available_filter_input.textChanged.connect(partial(self.edit_box_changed, which="available_filter_input"))
+            connect_lambda(getattr(self, x).textChanged, self, lambda self: self.edit_box_changed(x))
-        self.applied_filter_input.textChanged.connect(partial(self.edit_box_changed, which="applied_filter_input"))
         getattr(self, gprefs.get('tag_editor_last_filter', 'add_tag_input')).setFocus()
 
         if islinux:

src/calibre/startup.py

@@ -153,6 +153,24 @@ if not _run_once:
     __builtin__.__dict__['icu_upper'] = icu_upper
     __builtin__.__dict__['icu_title'] = title_case
 
+    def connect_lambda(bound_signal, self, func, **kw):
+        import weakref
+        r = weakref.ref(self)
+        del self
+        num_args = func.__code__.co_argcount - 1
+        if num_args < 0:
+            raise TypeError('lambda must take at least one argument')
+
+        def slot(*args):
+            ctx = r()
+            if ctx is not None:
+                if len(args) != num_args:
+                    args = args[:num_args]
+                func(ctx, *args)
+
+        bound_signal.connect(slot, **kw)
+    __builtin__.__dict__['connect_lambda'] = connect_lambda
+
     if islinux:
         # Name all threads at the OS level created using the threading module, see
         # http://bugs.python.org/issue15500