1 # -*- Mode: Python; py-indent-offset: 4 -*-
2 # pygobject - Python bindings for the GObject library
3 # Copyright (C) 2007 Johan Dahlin
5 # gobject/propertyhelper.py: GObject property wrapper/helper
7 # This library is free software; you can redistribute it and/or
8 # modify it under the terms of the GNU Lesser General Public
9 # License as published by the Free Software Foundation; either
10 # version 2.1 of the License, or (at your option) any later version.
12 # This library is distributed in the hope that it will be useful,
13 # but WITHOUT ANY WARRANTY; without even the implied warranty of
14 # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15 # Lesser General Public License for more details.
17 # You should have received a copy of the GNU Lesser General Public
18 # License along with this library; if not, write to the Free Software
19 # Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301
24 from . import _gobject
26 from .constants import \
27 TYPE_NONE, TYPE_INTERFACE, TYPE_CHAR, TYPE_UCHAR, \
28 TYPE_BOOLEAN, TYPE_INT, TYPE_UINT, TYPE_LONG, \
29 TYPE_ULONG, TYPE_INT64, TYPE_UINT64, TYPE_ENUM, TYPE_FLAGS, \
30 TYPE_FLOAT, TYPE_DOUBLE, TYPE_STRING, \
31 TYPE_POINTER, TYPE_BOXED, TYPE_PARAM, TYPE_OBJECT, \
32 TYPE_PYOBJECT, TYPE_GTYPE, TYPE_STRV, TYPE_VARIANT
33 from ._gobject import \
34 G_MAXFLOAT, G_MAXDOUBLE, \
35 G_MININT, G_MAXINT, G_MAXUINT, G_MINLONG, G_MAXLONG, \
38 if sys.version_info >= (3, 0):
42 _basestring = basestring
46 class Property(object):
48 Creates a new property which in conjunction with GObject subclass will
49 create a property proxy:
51 >>> class MyObject(GObject.GObject):
52 >>> ... prop = GObject.Property(type=str)
55 >>> obj.prop = 'value'
60 The API is similar to the builtin property:
62 class AnotherObject(GObject.GObject):
65 '''Read only property.'''
68 @GObject.Property(type=int)
70 '''Read-write integer property.'''
74 def propInt(self, value):
77 _type_from_pytype_lookup = {
78 # Put long_ first in case long_ and int are the same so int clobbers long_
84 object: TYPE_PYOBJECT,
91 # Remember that G_MINFLOAT and G_MINDOUBLE are something different.
92 TYPE_FLOAT: -G_MAXFLOAT,
93 TYPE_DOUBLE: -G_MAXDOUBLE,
100 TYPE_UINT: G_MAXUINT,
101 TYPE_ULONG: G_MAXULONG,
102 TYPE_INT64: 2 ** 63 - 1,
103 TYPE_UINT64: 2 ** 64 - 1,
104 TYPE_FLOAT: G_MAXFLOAT,
105 TYPE_DOUBLE: G_MAXDOUBLE,
107 TYPE_LONG: G_MAXLONG,
122 class __metaclass__(type):
124 return "<class 'GObject.Property'>"
126 def __init__(self, getter=None, setter=None, type=None, default=None,
127 nick='', blurb='', flags=_gobject.PARAM_READWRITE,
128 minimum=None, maximum=None):
130 @param getter: getter to get the value of the property
131 @type getter: callable
132 @param setter: setter to set the value of the property
133 @type setter: callable
134 @param type: type of property
136 @param default: default value
137 @param nick: short description
139 @param blurb: long description
141 @param flags: parameter flags, one of:
142 - gobject.PARAM_READABLE
143 - gobject.PARAM_READWRITE
144 - gobject.PARAM_WRITABLE
145 - gobject.PARAM_CONSTRUCT
146 - gobject.PARAM_CONSTRUCT_ONLY
147 - gobject.PARAM_LAX_VALIDATION
148 @keyword minimum: minimum allowed value (int, float, long only)
149 @keyword maximum: maximum allowed value (int, float, long only)
154 self.type = self._type_from_python(type)
155 self.default = self._get_default(default)
156 self._check_default()
158 if not isinstance(nick, _basestring):
159 raise TypeError("nick must be a string")
162 if not isinstance(blurb, _basestring):
163 raise TypeError("blurb must be a string")
165 # Always clobber __doc__ with blurb even if blurb is empty because
166 # we don't want the lengthy Property class documentation showing up
170 if flags < 0 or flags > 32:
171 raise TypeError("invalid flag value: %r" % (flags,))
174 # Call after setting blurb for potential __doc__ usage.
175 if getter and not setter:
176 setter = self._readonly_setter
177 elif setter and not getter:
178 getter = self._writeonly_getter
179 elif not setter and not getter:
180 getter = self._default_getter
181 setter = self._default_setter
185 if minimum is not None:
186 if minimum < self._get_minimum():
188 "Minimum for type %s cannot be lower than %d" % (
189 self.type, self._get_minimum()))
191 minimum = self._get_minimum()
192 self.minimum = minimum
193 if maximum is not None:
194 if maximum > self._get_maximum():
196 "Maximum for type %s cannot be higher than %d" % (
197 self.type, self._get_maximum()))
199 maximum = self._get_maximum()
200 self.maximum = maximum
207 return '<GObject Property %s (%s)>' % (
208 self.name or '(uninitialized)',
209 _gobject.type_name(self.type))
211 def __get__(self, instance, klass):
216 value = instance.get_property(self.name)
224 def __set__(self, instance, value):
229 instance.set_property(self.name, value)
235 def __call__(self, fget):
236 """Allows application of the getter along with init arguments."""
237 return self.getter(fget)
239 def getter(self, fget):
240 """Set the getter function to fget. For use as a decorator."""
242 # Always clobber docstring and blurb with the getter docstring.
243 self.blurb = fget.__doc__
244 self.__doc__ = fget.__doc__
248 def setter(self, fset):
249 """Set the setter function to fset. For use as a decorator."""
253 def _type_from_python(self, type_):
254 if type_ in self._type_from_pytype_lookup:
255 return self._type_from_pytype_lookup[type_]
256 elif (isinstance(type_, type) and
257 issubclass(type_, (_gobject.GObject,
261 return type_.__gtype__
262 elif type_ in (TYPE_NONE, TYPE_INTERFACE, TYPE_CHAR, TYPE_UCHAR,
263 TYPE_INT, TYPE_UINT, TYPE_BOOLEAN, TYPE_LONG,
264 TYPE_ULONG, TYPE_INT64, TYPE_UINT64,
265 TYPE_FLOAT, TYPE_DOUBLE, TYPE_POINTER,
266 TYPE_BOXED, TYPE_PARAM, TYPE_OBJECT, TYPE_STRING,
267 TYPE_PYOBJECT, TYPE_GTYPE, TYPE_STRV, TYPE_VARIANT):
270 raise TypeError("Unsupported type: %r" % (type_,))
272 def _get_default(self, default):
273 if default is not None:
275 return self._default_lookup.get(self.type, None)
277 def _check_default(self):
279 default = self.default
280 if (ptype == TYPE_BOOLEAN and (default not in (True, False))):
282 "default must be True or False, not %r" % (default,))
283 elif ptype == TYPE_PYOBJECT:
284 if default is not None:
285 raise TypeError("object types does not have default values")
286 elif ptype == TYPE_GTYPE:
287 if default is not None:
288 raise TypeError("GType types does not have default values")
289 elif _gobject.type_is_a(ptype, TYPE_ENUM):
291 raise TypeError("enum properties needs a default value")
292 elif not _gobject.type_is_a(default, ptype):
293 raise TypeError("enum value %s must be an instance of %r" %
295 elif _gobject.type_is_a(ptype, TYPE_FLAGS):
296 if not _gobject.type_is_a(default, ptype):
297 raise TypeError("flags value %s must be an instance of %r" %
299 elif _gobject.type_is_a(ptype, TYPE_STRV) and default is not None:
300 if not isinstance(default, list):
301 raise TypeError("Strv value %s must be a list" % repr(default))
303 if type(val) not in (str, bytes):
304 raise TypeError("Strv value %s must contain only strings" % str(default))
305 elif _gobject.type_is_a(ptype, TYPE_VARIANT) and default is not None:
306 if not hasattr(default, '__gtype__') or not _gobject.type_is_a(default, TYPE_VARIANT):
307 raise TypeError("variant value %s must be an instance of %r" %
310 def _get_minimum(self):
311 return self._min_value_lookup.get(self.type, None)
313 def _get_maximum(self):
314 return self._max_value_lookup.get(self.type, None)
320 def _default_setter(self, instance, value):
321 setattr(instance, '_property_helper_' + self.name, value)
323 def _default_getter(self, instance):
324 return getattr(instance, '_property_helper_' + self.name, self.default)
326 def _readonly_setter(self, instance, value):
327 self._exc = TypeError("%s property of %s is read-only" % (
328 self.name, type(instance).__name__))
330 def _writeonly_getter(self, instance):
331 self._exc = TypeError("%s property of %s is write-only" % (
332 self.name, type(instance).__name__))
338 def get_pspec_args(self):
340 if ptype in (TYPE_INT, TYPE_UINT, TYPE_LONG, TYPE_ULONG,
341 TYPE_INT64, TYPE_UINT64, TYPE_FLOAT, TYPE_DOUBLE):
342 args = self.minimum, self.maximum, self.default
343 elif (ptype == TYPE_STRING or ptype == TYPE_BOOLEAN or
344 ptype.is_a(TYPE_ENUM) or ptype.is_a(TYPE_FLAGS) or
345 ptype.is_a(TYPE_VARIANT)):
346 args = (self.default,)
347 elif ptype in (TYPE_PYOBJECT, TYPE_GTYPE):
349 elif ptype.is_a(TYPE_OBJECT) or ptype.is_a(TYPE_BOXED):
352 raise NotImplementedError(ptype)
354 return (self.type, self.nick, self.blurb) + args + (self.flags,)
357 def install_properties(cls):
359 Scans the given class for instances of Property and merges them
360 into the classes __gproperties__ dict if it exists or adds it if not.
362 gproperties = cls.__dict__.get('__gproperties__', {})
365 for name, prop in cls.__dict__.items():
366 if isinstance(prop, Property): # not same as the built-in
367 if name in gproperties:
368 raise ValueError('Property %s was already found in __gproperties__' % name)
370 gproperties[name] = prop.get_pspec_args()
376 cls.__gproperties__ = gproperties
378 if 'do_get_property' in cls.__dict__ or 'do_set_property' in cls.__dict__:
380 if prop.fget != prop._default_getter or prop.fset != prop._default_setter:
382 "GObject subclass %r defines do_get/set_property"
383 " and it also uses a property with a custom setter"
384 " or getter. This is not allowed" % (
387 def obj_get_property(self, pspec):
388 name = pspec.name.replace('-', '_')
389 prop = getattr(cls, name, None)
391 return prop.fget(self)
392 cls.do_get_property = obj_get_property
394 def obj_set_property(self, pspec, value):
395 name = pspec.name.replace('-', '_')
396 prop = getattr(cls, name, None)
398 prop.fset(self, value)
399 cls.do_set_property = obj_set_property