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# -*- Mode: Python; py-indent-offset: 4 -*-
# pygobject - Python bindings for the GObject library
# Copyright (C) 2007 Johan Dahlin
#
# gobject/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, write to the Free Software
# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301
# USA
import sys
import gobject._gobject
_gobject = sys.modules['gobject._gobject']
from gobject.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
from gobject.constants import \
G_MINFLOAT, G_MAXFLOAT, G_MINDOUBLE, G_MAXDOUBLE, \
G_MININT, G_MAXINT, G_MAXUINT, G_MINLONG, G_MAXLONG, \
G_MAXULONG
class property(object):
"""
Creates a new property which in conjunction with GObject subclass will
create a property proxy:
>>> class MyObject(gobject.GObject):
>>> ... prop = gobject.property(type=str)
>>> obj = MyObject()
>>> obj.prop = 'value'
>>> obj.prop
'value'
The API is similar to the builtin property:
class AnotherObject(gobject.GObject):
@gobject.property
def prop(self):
return ...
Which will create a read-only property called prop.
"""
class __metaclass__(type):
def __repr__(self):
return "<class 'gobject.property'>"
def __init__(self, getter=None, setter=None, type=None, default=None,
nick='', blurb='', flags=_gobject.PARAM_READWRITE,
minimum=None, maximum=None):
"""
@param getter: getter to get the value of the property
@type getter: callable
@param setter: setter to set the value of the property
@type setter: callable
@param type: type of property
@type type: type
@param default: default value
@param nick: short description
@type bick: string
@param blurb: long description
@type blurb: string
@param flags: parameter flags, one of:
- gobject.PARAM_READABLE
- gobject.PARAM_READWRITE
- gobject.PARAM_WRITABLE
- gobject.PARAM_CONSTRUCT
- gobject.PARAM_CONSTRUCT_ONLY
- gobject.PARAM_LAX_VALIDATION
@keyword minimum: minimum allowed value (int, float, long only)
@keyword maximum: maximum allowed value (int, float, long only)
"""
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
self.setter = setter
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
if flags < 0 or flags > 32:
raise TypeError("invalid flag value: %r" % (flags,))
self.flags = flags
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.name = None
self._values = {}
self._exc = None
def __repr__(self):
return '<gobject property %s (%s)>' % (
self.name or '(uninitialized)',
_gobject.type_name(self.type))
def __get__(self, instance, klass):
if instance is None:
return self
self._exc = None
value = instance.get_property(self.name)
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 _type_from_python(self, type):
if type == int:
return TYPE_INT
elif type == bool:
return TYPE_BOOLEAN
elif type == long:
return TYPE_LONG
elif type == float:
return TYPE_DOUBLE
elif type == str:
return TYPE_STRING
elif type == object:
return TYPE_PYOBJECT
elif type == _gobject.GObject:
return TYPE_OBJECT
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_ENUM,
TYPE_FLAGS, TYPE_FLOAT, TYPE_DOUBLE, TYPE_POINTER,
TYPE_BOXED, TYPE_PARAM, TYPE_OBJECT, TYPE_STRING,
TYPE_PYOBJECT]:
return type
else:
raise TypeError("Unsupported type: %r" % (type,))
def _get_default(self, default):
ptype = self.type
if default is not None:
return default
if ptype in [TYPE_INT, TYPE_UINT, TYPE_LONG, TYPE_ULONG,
TYPE_INT64, TYPE_UINT64]:
return 0
elif ptype == TYPE_STRING:
return ''
elif ptype == TYPE_FLOAT or ptype == TYPE_DOUBLE:
return 0.0
else:
return 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")
def _get_minimum(self):
ptype = self.type
if ptype in [TYPE_UINT, TYPE_ULONG, TYPE_UINT64]:
return 0
# Remember that G_MINFLOAT and G_MINDOUBLE are something different.
elif ptype == TYPE_FLOAT:
return -G_MAXFLOAT
elif ptype == TYPE_DOUBLE:
return -G_MAXDOUBLE
elif ptype == TYPE_INT:
return G_MININT
elif ptype == TYPE_LONG:
return G_MINLONG
elif ptype == TYPE_INT64:
return -2 ** 62 - 1
return None
def _get_maximum(self):
ptype = self.type
if ptype == TYPE_UINT:
return G_MAXUINT
elif ptype == TYPE_ULONG:
return G_MAXULONG
elif ptype == TYPE_INT64:
return 2 ** 62 - 1
elif ptype == TYPE_UINT64:
return 2 ** 63 - 1
elif ptype == TYPE_FLOAT:
return G_MAXFLOAT
elif ptype == TYPE_DOUBLE:
return G_MAXDOUBLE
elif ptype == TYPE_INT:
return G_MAXINT
elif ptype == TYPE_LONG:
return G_MAXLONG
return None
#
# Getter and Setter
#
def _default_setter(self, instance, value):
self._values[instance] = value
def _default_getter(self, instance):
return self._values.get(instance, 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._get_minimum(), self._get_maximum(), self.default
elif ptype == TYPE_STRING or ptype == TYPE_BOOLEAN:
args = (self.default,)
elif ptype == TYPE_PYOBJECT:
args = ()
elif ptype == TYPE_OBJECT:
args = ()
else:
raise NotImplementedError(ptype)
return (self.type, self.nick, self.blurb) + args + (self.flags,)
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