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# -*- Mode: Python; py-indent-offset: 4 -*-
# pygobject - Python bindings for the GObject library
# Copyright (C) 2007 Johan Dahlin
#
# gi/_propertyhelper.py: GObject property wrapper/helper
#
# 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
import traceback
from . import _gi
from ._constants import \
TYPE_NONE, TYPE_INTERFACE, TYPE_CHAR, TYPE_UCHAR, \
TYPE_BOOLEAN, TYPE_INT, TYPE_UINT, TYPE_LONG, \
TYPE_ULONG, TYPE_INT64, TYPE_UINT64, TYPE_ENUM, TYPE_FLAGS, \
TYPE_FLOAT, TYPE_DOUBLE, TYPE_STRING, \
TYPE_POINTER, TYPE_BOXED, TYPE_PARAM, TYPE_OBJECT, \
TYPE_PYOBJECT, TYPE_GTYPE, TYPE_STRV, TYPE_VARIANT
G_MAXFLOAT = _gi.G_MAXFLOAT
G_MAXDOUBLE = _gi.G_MAXDOUBLE
G_MININT = _gi.G_MININT
G_MAXINT = _gi.G_MAXINT
G_MAXUINT = _gi.G_MAXUINT
G_MINLONG = _gi.G_MINLONG
G_MAXLONG = _gi.G_MAXLONG
G_MAXULONG = _gi.G_MAXULONG
if sys.version_info >= (3, 0):
_basestring = str
_long = int
else:
_basestring = basestring
_long = long
class Property(object):
"""Creates a new Property which when used in conjunction with
GObject subclass will create a Python property accessor for the
GObject ParamSpec.
:param callable getter:
getter to get the value of the property
:param callable setter:
setter to set the value of the property
:param type type:
type of property
:param default:
default value, must match the property type.
:param str nick:
short description
:param str blurb:
long description
:param GObject.ParamFlags flags:
parameter flags
:keyword minimum:
minimum allowed value (int, float, long only)
:keyword maximum:
maximum allowed value (int, float, long only)
.. code-block:: python
class MyObject(GObject.Object):
prop = GObject.Property(type=str)
obj = MyObject()
obj.prop = 'value'
obj.prop # now is 'value'
The API is similar to the builtin :py:func:`property`:
.. code-block:: python
class AnotherObject(GObject.Object):
value = 0
@GObject.Property
def prop(self):
'Read only property.'
return 1
@GObject.Property(type=int)
def propInt(self):
'Read-write integer property.'
return self.value
@propInt.setter
def propInt(self, value):
self.value = value
"""
_type_from_pytype_lookup = {
# Put long_ first in case long_ and int are the same so int clobbers long_
_long: TYPE_LONG,
int: TYPE_INT,
bool: TYPE_BOOLEAN,
float: TYPE_DOUBLE,
str: TYPE_STRING,
object: TYPE_PYOBJECT,
}
_min_value_lookup = {
TYPE_UINT: 0,
TYPE_ULONG: 0,
TYPE_UINT64: 0,
# Remember that G_MINFLOAT and G_MINDOUBLE are something different.
TYPE_FLOAT: -G_MAXFLOAT,
TYPE_DOUBLE: -G_MAXDOUBLE,
TYPE_INT: G_MININT,
TYPE_LONG: G_MINLONG,
TYPE_INT64: -2 ** 63,
}
_max_value_lookup = {
TYPE_UINT: G_MAXUINT,
TYPE_ULONG: G_MAXULONG,
TYPE_INT64: 2 ** 63 - 1,
TYPE_UINT64: 2 ** 64 - 1,
TYPE_FLOAT: G_MAXFLOAT,
TYPE_DOUBLE: G_MAXDOUBLE,
TYPE_INT: G_MAXINT,
TYPE_LONG: G_MAXLONG,
}
_default_lookup = {
TYPE_INT: 0,
TYPE_UINT: 0,
TYPE_LONG: 0,
TYPE_ULONG: 0,
TYPE_INT64: 0,
TYPE_UINT64: 0,
TYPE_STRING: '',
TYPE_FLOAT: 0.0,
TYPE_DOUBLE: 0.0,
}
class __metaclass__(type):
def __repr__(self):
return "<class 'GObject.Property'>"
def __init__(self, getter=None, setter=None, type=None, default=None,
nick='', blurb='', flags=_gi.PARAM_READWRITE,
minimum=None, maximum=None):
self.name = None
if type is None:
type = object
self.type = self._type_from_python(type)
self.default = self._get_default(default)
self._check_default()
if not isinstance(nick, _basestring):
raise TypeError("nick must be a string")
self.nick = nick
if not isinstance(blurb, _basestring):
raise TypeError("blurb must be a string")
self.blurb = blurb
# Always clobber __doc__ with blurb even if blurb is empty because
# we don't want the lengthy Property class documentation showing up
# on instances.
self.__doc__ = blurb
self.flags = flags
# Call after setting blurb for potential __doc__ usage.
if getter and not setter:
setter = self._readonly_setter
elif setter and not getter:
getter = self._writeonly_getter
elif not setter and not getter:
getter = self._default_getter
setter = self._default_setter
self.getter(getter)
# do not call self.setter() here, as this defines the property name
# already
self.fset = setter
if minimum is not None:
if minimum < self._get_minimum():
raise TypeError(
"Minimum for type %s cannot be lower than %d" %
(self.type, self._get_minimum()))
else:
minimum = self._get_minimum()
self.minimum = minimum
if maximum is not None:
if maximum > self._get_maximum():
raise TypeError(
"Maximum for type %s cannot be higher than %d" %
(self.type, self._get_maximum()))
else:
maximum = self._get_maximum()
self.maximum = maximum
self._exc = None
def __repr__(self):
return '<GObject Property %s (%s)>' % (
self.name or '(uninitialized)',
_gi.type_name(self.type))
def __get__(self, instance, klass):
if instance is None:
return self
self._exc = None
# Simply return the result of fget directly, no need to go through GObject.
# See: https://bugzilla.gnome.org/show_bug.cgi?id=723872
# We catch and print any exception occurring within the fget for compatibility
# prior to the fast path addition from bug 723872, this should eventually
# be removed and exceptions raised directly to the caller as in:
# https://bugzilla.gnome.org/show_bug.cgi?id=575652
try:
value = self.fget(instance)
except Exception:
traceback.print_exc()
value = None
if self._exc:
exc = self._exc
self._exc = None
raise exc
return value
def __set__(self, instance, value):
if instance is None:
raise TypeError
self._exc = None
instance.set_property(self.name, value)
if self._exc:
exc = self._exc
self._exc = None
raise exc
def __call__(self, fget):
"""Allows application of the getter along with init arguments."""
return self.getter(fget)
def getter(self, fget):
"""Set the getter function to fget. For use as a decorator."""
if fget.__doc__:
# Always clobber docstring and blurb with the getter docstring.
self.blurb = fget.__doc__
self.__doc__ = fget.__doc__
self.fget = fget
return self
def setter(self, fset):
"""Set the setter function to fset. For use as a decorator."""
self.fset = fset
# with a setter decorator, we must ignore the name of the method in
# install_properties, as this does not need to be a valid property name
# and does not define the property name. So set the name here.
if not self.name:
self.name = self.fget.__name__
return self
def _type_from_python(self, type_):
if type_ in self._type_from_pytype_lookup:
return self._type_from_pytype_lookup[type_]
elif (isinstance(type_, type) and
issubclass(type_, (_gi.GObject,
_gi.GEnum,
_gi.GFlags,
_gi.GBoxed,
_gi.GInterface))):
return type_.__gtype__
elif type_ in (TYPE_NONE, TYPE_INTERFACE, TYPE_CHAR, TYPE_UCHAR,
TYPE_INT, TYPE_UINT, TYPE_BOOLEAN, TYPE_LONG,
TYPE_ULONG, TYPE_INT64, TYPE_UINT64,
TYPE_FLOAT, TYPE_DOUBLE, TYPE_POINTER,
TYPE_BOXED, TYPE_PARAM, TYPE_OBJECT, TYPE_STRING,
TYPE_PYOBJECT, TYPE_GTYPE, TYPE_STRV, TYPE_VARIANT):
return type_
else:
raise TypeError("Unsupported type: %r" % (type_,))
def _get_default(self, default):
if default is not None:
return default
return self._default_lookup.get(self.type, None)
def _check_default(self):
ptype = self.type
default = self.default
if (ptype == TYPE_BOOLEAN and (default not in (True, False))):
raise TypeError(
"default must be True or False, not %r" % (default,))
elif ptype == TYPE_PYOBJECT:
if default is not None:
raise TypeError("object types does not have default values")
elif ptype == TYPE_GTYPE:
if default is not None:
raise TypeError("GType types does not have default values")
elif _gi.type_is_a(ptype, TYPE_ENUM):
if default is None:
raise TypeError("enum properties needs a default value")
elif not _gi.type_is_a(default, ptype):
raise TypeError("enum value %s must be an instance of %r" %
(default, ptype))
elif _gi.type_is_a(ptype, TYPE_FLAGS):
if not _gi.type_is_a(default, ptype):
raise TypeError("flags value %s must be an instance of %r" %
(default, ptype))
elif _gi.type_is_a(ptype, TYPE_STRV) and default is not None:
if not isinstance(default, list):
raise TypeError("Strv value %s must be a list" % repr(default))
for val in default:
if type(val) not in (str, bytes):
raise TypeError("Strv value %s must contain only strings" % str(default))
elif _gi.type_is_a(ptype, TYPE_VARIANT) and default is not None:
if not hasattr(default, '__gtype__') or not _gi.type_is_a(default, TYPE_VARIANT):
raise TypeError("variant value %s must be an instance of %r" %
(default, ptype))
def _get_minimum(self):
return self._min_value_lookup.get(self.type, None)
def _get_maximum(self):
return self._max_value_lookup.get(self.type, None)
#
# Getter and Setter
#
def _default_setter(self, instance, value):
setattr(instance, '_property_helper_' + self.name, value)
def _default_getter(self, instance):
return getattr(instance, '_property_helper_' + self.name, self.default)
def _readonly_setter(self, instance, value):
self._exc = TypeError("%s property of %s is read-only" % (
self.name, type(instance).__name__))
def _writeonly_getter(self, instance):
self._exc = TypeError("%s property of %s is write-only" % (
self.name, type(instance).__name__))
#
# Public API
#
def get_pspec_args(self):
ptype = self.type
if ptype in (TYPE_INT, TYPE_UINT, TYPE_LONG, TYPE_ULONG,
TYPE_INT64, TYPE_UINT64, TYPE_FLOAT, TYPE_DOUBLE):
args = self.minimum, self.maximum, self.default
elif (ptype == TYPE_STRING or ptype == TYPE_BOOLEAN or
ptype.is_a(TYPE_ENUM) or ptype.is_a(TYPE_FLAGS) or
ptype.is_a(TYPE_VARIANT)):
args = (self.default,)
elif ptype in (TYPE_PYOBJECT, TYPE_GTYPE):
args = ()
elif ptype.is_a(TYPE_OBJECT) or ptype.is_a(TYPE_BOXED):
args = ()
else:
raise NotImplementedError(ptype)
return (self.type, self.nick, self.blurb) + args + (self.flags,)
def install_properties(cls):
"""
Scans the given class for instances of Property and merges them
into the classes __gproperties__ dict if it exists or adds it if not.
"""
gproperties = cls.__dict__.get('__gproperties__', {})
props = []
for name, prop in cls.__dict__.items():
if isinstance(prop, Property): # not same as the built-in
# if a property was defined with a decorator, it may already have
# a name; if it was defined with an assignment (prop = Property(...))
# we set the property's name to the member name
if not prop.name:
prop.name = name
# we will encounter the same property multiple times in case of
# custom setter methods
if prop.name in gproperties:
if gproperties[prop.name] == prop.get_pspec_args():
continue
raise ValueError('Property %s was already found in __gproperties__' % prop.name)
gproperties[prop.name] = prop.get_pspec_args()
props.append(prop)
if not props:
return
cls.__gproperties__ = gproperties
if 'do_get_property' in cls.__dict__ or 'do_set_property' in cls.__dict__:
for prop in props:
if prop.fget != prop._default_getter or prop.fset != prop._default_setter:
raise TypeError(
"GObject subclass %r defines do_get/set_property"
" and it also uses a property with a custom setter"
" or getter. This is not allowed" %
(cls.__name__,))
def obj_get_property(self, pspec):
name = pspec.name.replace('-', '_')
return getattr(self, name, None)
cls.do_get_property = obj_get_property
def obj_set_property(self, pspec, value):
name = pspec.name.replace('-', '_')
prop = getattr(cls, name, None)
if prop:
prop.fset(self, value)
cls.do_set_property = obj_set_property
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