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_signalhelper.py
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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 ._gi import _gobject # 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=_gobject.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, _gobject.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)