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# -*- Mode: Python; py-indent-offset: 4 -*-
# pygobject - Python bindings for the GObject library
# Copyright (C) 2012 Simon Feltman
#
# gi/_signalhelper.py: GObject signal binding decorator object
#
# This library is free software; you can redistribute it and/or
# modify it under the terms of the GNU Lesser General Public
# License as published by the Free Software Foundation; either
# version 2.1 of the License, or (at your option) any later version.
#
# This library is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
# Lesser General Public License for more details.
#
# You should have received a copy of the GNU Lesser General Public
# License along with this library; if not, see <http://www.gnu.org/licenses/>.
import sys
from . import _gi
# Callable went away in python 3.0 and came back in 3.2.
# Use versioning to figure out when to define it, otherwise we have to deal with
# the complexity of using __builtin__ or builtin between python versions to
# check if callable exists which PyFlakes will also complain about.
if (3, 0) <= sys.version_info < (3, 2):
def callable(fn):
return hasattr(fn, '__call__')
class Signal(str):
"""Object which gives a nice API for creating and binding signals.
:param name:
Name of signal or callable closure when used as a decorator.
:type name: str or callable
:param callable func:
Callable closure method.
:param GObject.SignalFlags flags:
Flags specifying when to run closure.
:param type return_type:
Return type of the Signal.
:param list arg_types:
List of argument types specifying the signals function signature
:param str doc:
Documentation of signal object.
:param callable accumulator:
Accumulator method with the signature:
func(ihint, return_accu, handler_return, accu_data) -> boolean
:param object accu_data:
User data passed to the accumulator.
:Example:
.. code-block:: python
class Spam(GObject.Object):
velocity = 0
@GObject.Signal
def pushed(self):
self.velocity += 1
@GObject.Signal(flags=GObject.SignalFlags.RUN_LAST)
def pulled(self):
self.velocity -= 1
stomped = GObject.Signal('stomped', arg_types=(int,))
@GObject.Signal
def annotated_signal(self, a:int, b:str):
"Python3 annotation support for parameter types.
def on_pushed(obj):
print(obj)
spam = Spam()
spam.pushed.connect(on_pushed)
spam.pushed.emit()
"""
class BoundSignal(str):
"""
Temporary binding object which can be used for connecting signals
without specifying the signal name string to connect.
"""
def __new__(cls, name, *args, **kargs):
return str.__new__(cls, name)
def __init__(self, signal, gobj):
str.__init__(self)
self.signal = signal
self.gobj = gobj
def __repr__(self):
return 'BoundSignal("%s")' % self
def __call__(self, *args, **kargs):
"""Call the signals closure."""
return self.signal.func(self.gobj, *args, **kargs)
def connect(self, callback, *args, **kargs):
"""Same as GObject.Object.connect except there is no need to specify
the signal name."""
return self.gobj.connect(self, callback, *args, **kargs)
def connect_detailed(self, callback, detail, *args, **kargs):
"""Same as GObject.Object.connect except there is no need to specify
the signal name. In addition concats "::<detail>" to the signal name
when connecting; for use with notifications like "notify" when a property
changes.
"""
return self.gobj.connect(self + '::' + detail, callback, *args, **kargs)
def disconnect(self, handler_id):
"""Same as GObject.Object.disconnect."""
self.instance.disconnect(handler_id)
def emit(self, *args, **kargs):
"""Same as GObject.Object.emit except there is no need to specify
the signal name."""
return self.gobj.emit(str(self), *args, **kargs)
def __new__(cls, name='', *args, **kargs):
if callable(name):
name = name.__name__
return str.__new__(cls, name)
def __init__(self, name='', func=None, flags=_gi.SIGNAL_RUN_FIRST,
return_type=None, arg_types=None, doc='', accumulator=None, accu_data=None):
if func and not name:
name = func.__name__
elif callable(name):
func = name
name = func.__name__
if func and not doc:
doc = func.__doc__
str.__init__(self)
if func and not (return_type or arg_types):
return_type, arg_types = get_signal_annotations(func)
if arg_types is None:
arg_types = tuple()
self.func = func
self.flags = flags
self.return_type = return_type
self.arg_types = arg_types
self.__doc__ = doc
self.accumulator = accumulator
self.accu_data = accu_data
def __get__(self, instance, owner=None):
"""Returns a BoundSignal when accessed on an object instance."""
if instance is None:
return self
return self.BoundSignal(self, instance)
def __call__(self, obj, *args, **kargs):
"""Allows for instantiated Signals to be used as a decorator or calling
of the underlying signal method."""
# If obj is a GObject, than we call this signal as a closure otherwise
# it is used as a re-application of a decorator.
if isinstance(obj, _gi.GObject):
self.func(obj, *args, **kargs)
else:
# If self is already an allocated name, use it otherwise create a new named
# signal using the closure name as the name.
if str(self):
name = str(self)
else:
name = obj.__name__
# Return a new value of this type since it is based on an immutable string.
return type(self)(name=name, func=obj, flags=self.flags,
return_type=self.return_type, arg_types=self.arg_types,
doc=self.__doc__, accumulator=self.accumulator, accu_data=self.accu_data)
def copy(self, newName=None):
"""Returns a renamed copy of the Signal."""
if newName is None:
newName = self.name
return type(self)(name=newName, func=self.func, flags=self.flags,
return_type=self.return_type, arg_types=self.arg_types,
doc=self.__doc__, accumulator=self.accumulator, accu_data=self.accu_data)
def get_signal_args(self):
"""Returns a tuple of: (flags, return_type, arg_types, accumulator, accu_data)"""
return (self.flags, self.return_type, self.arg_types, self.accumulator, self.accu_data)
class SignalOverride(Signal):
"""Specialized sub-class of Signal which can be used as a decorator for overriding
existing signals on GObjects.
:Example:
.. code-block:: python
class MyWidget(Gtk.Widget):
@GObject.SignalOverride
def configure_event(self):
pass
"""
def get_signal_args(self):
"""Returns the string 'override'."""
return 'override'
def get_signal_annotations(func):
"""Attempt pulling python 3 function annotations off of 'func' for
use as a signals type information. Returns an ordered nested tuple
of (return_type, (arg_type1, arg_type2, ...)). If the given function
does not have annotations then (None, tuple()) is returned.
"""
arg_types = tuple()
return_type = None
if hasattr(func, '__annotations__'):
# import inspect only when needed because it takes ~10 msec to load
import inspect
spec = inspect.getfullargspec(func)
arg_types = tuple(spec.annotations[arg] for arg in spec.args
if arg in spec.annotations)
if 'return' in spec.annotations:
return_type = spec.annotations['return']
return return_type, arg_types
def install_signals(cls):
"""Adds Signal instances on a GObject derived class into the '__gsignals__'
dictionary to be picked up and registered as real GObject signals.
"""
gsignals = cls.__dict__.get('__gsignals__', {})
newsignals = {}
for name, signal in cls.__dict__.items():
if isinstance(signal, Signal):
signalName = str(signal)
# Fixup a signal which is unnamed by using the class variable name.
# Since Signal is based on string which immutable,
# we must copy and replace the class variable.
if not signalName:
signalName = name
signal = signal.copy(name)
setattr(cls, name, signal)
if signalName in gsignals:
raise ValueError('Signal "%s" has already been registered.' % name)
newsignals[signalName] = signal
gsignals[signalName] = signal.get_signal_args()
cls.__gsignals__ = gsignals
# Setup signal closures by adding the specially named
# method to the class in the form of "do_<signal_name>".
for name, signal in newsignals.items():
if signal.func is not None:
funcName = 'do_' + name.replace('-', '_')
if not hasattr(cls, funcName):
setattr(cls, funcName, signal.func)
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