在 PyGTK/GObject 中使用枚举属性
本教程介绍如何在Python 仅涵盖使用 gobject.TYPE_FLOAT 类型的属性。
我已将其调整为使用枚举类型：
import pygtk
pygtk.require('2.0')
import gobject
FUEL_NONE = 0
FUEL_SOME = 1
FUEL_FULL = 2
class Car(gobject.GObject):
__gproperties__ = {
'fuel' : (gobject.TYPE_ENUM, # type
'fuel of the car', # nick name
'amount of fuel that remains in the tank', # description
FUEL_SOME, # default value
gobject.PARAM_READWRITE) # flags
}
# <<rest of demo code>>
...但是当我尝试运行它时，出现以下错误：
/usr/lib/pymodules/python2.5/gtk-2.0/gobject/__init__.py:114: Warning: g_param_spec_enum: assertion `g_enum_get_value (enum_class, default_value) != NULL' failed
type_register(cls, namespace.get('__gtype_name__'))
Traceback (most recent call last):
File "gcar.py", line 9, in <module>
class Car(gobject.GObject):
File "/usr/lib/pymodules/python2.5/gtk-2.0/gobject/__init__.py", line 60, in __init__
cls._type_register(cls.__dict__)
File "/usr/lib/pymodules/python2.5/gtk-2.0/gobject/__init__.py", line 114, in _type_register
type_register(cls, namespace.get('__gtype_name__'))
TypeError: Error when calling the metaclass bases
could not create param spec for type GEnum (while registering property 'fuel' for GType '__main__+Car')
我缺少什么？
This tutorial on using GObject in Python only covers using a property of type gobject.TYPE_FLOAT.
I've adapted it to use an enumerated type:
import pygtk
pygtk.require('2.0')
import gobject
FUEL_NONE = 0
FUEL_SOME = 1
FUEL_FULL = 2
class Car(gobject.GObject):
__gproperties__ = {
'fuel' : (gobject.TYPE_ENUM, # type
'fuel of the car', # nick name
'amount of fuel that remains in the tank', # description
FUEL_SOME, # default value
gobject.PARAM_READWRITE) # flags
}
# <<rest of demo code>>
...but when I attempt to run it I get the following error:
/usr/lib/pymodules/python2.5/gtk-2.0/gobject/__init__.py:114: Warning: g_param_spec_enum: assertion `g_enum_get_value (enum_class, default_value) != NULL' failed
type_register(cls, namespace.get('__gtype_name__'))
Traceback (most recent call last):
File "gcar.py", line 9, in <module>
class Car(gobject.GObject):
File "/usr/lib/pymodules/python2.5/gtk-2.0/gobject/__init__.py", line 60, in __init__
cls._type_register(cls.__dict__)
File "/usr/lib/pymodules/python2.5/gtk-2.0/gobject/__init__.py", line 114, in _type_register
type_register(cls, namespace.get('__gtype_name__'))
TypeError: Error when calling the metaclass bases
could not create param spec for type GEnum (while registering property 'fuel' for GType '__main__+Car')
What am I missing?
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仅仅告诉
__gproperties__它是一个枚举类型还不够；您需要向 GObject 类型系统注册枚举，然后使用从中获取的 GType 值而不是gobject.TYPE_ENUM。至少， C 语言就是这样实现的。我不确定 PyGTK 执行此操作的正确方法是什么，但它可能涉及编写 .defs 文件并在其上运行 pygobject-codegen-2.0 。当然，将
gobject.TYPE_INT类型的属性设置为与枚举范围匹配的最小值和最大值可能更容易，除非您确实需要 GObject系统了解您的枚举的详细信息。It's not enough enough to tell
__gproperties__that it's an enumerated type; you need to register the enumeration with the GObject type system, and then use the GType value you get from that instead ofgobject.TYPE_ENUM. At least, that's how it's done in C. I'm not sure what the proper way to do this is PyGTK is, but it might involve writing a .defs file and runningpygobject-codegen-2.0on it.Of course, it's probably easier to just make the property of type
gobject.TYPE_INTwith a minimum and maximum value that matches the bounds of your enum, unless you really need the GObject system to understand the details of your enumeration.