问题描述
当你在程序中需要一些符号时，你在Python中使用了什么？
例如，一个对象得到一个状态。如果
表示为符号，则此状态更具可读性，例如打开，关闭，错误。
通常，在C或C ++中，我会用枚举：
enum OBJECT_STATE
{
打开，关闭，错误
}
在CAML或Haskell中我会使用联合类型：
类型ObjectState = Opened |关闭|错误
在Ruby中我会使用符号：
object.state =：open
object.state =：关闭
object.state =：错误
....但我不知道在Python中使用什么！
谢谢，
Pierre
When you need some symbols in your program, what do you use in Python ?
For example, an object get a state. This state is more readable if
expressed as a symbols, for example "opened", "closed", "error".
Typically, in C or C++, I would use an enum for that:
enum OBJECT_STATE
{
opened, closed, error
}
In CAML or Haskell I would use the union types:
type ObjectState = Opened | Closed | Error
In Ruby I would use the symbols :
object.state = :opened
object.state = :closed
object.state = :error
.... but I don''t know what to use in Python !
Thanks,
Pierre
推荐答案
OPENED，CLOSED，ERROR = range（ 3）
object.state = OPENED
-
Erik Max Francis&& &&
美国加利福尼亚州圣何塞市&& 37 20 N 121 53 W&& AIM erikmaxfrancis
无论谁命名为颈缩都是一个很差的解剖判断。
- 格劳乔·马克思
OPENED, CLOSED, ERROR = range(3)
object.state = OPENED
--
Erik Max Francis && ma*@alcyone.com && http://www.alcyone.com/max/
San Jose, CA, USA && 37 20 N 121 53 W && AIM erikmaxfrancis
Whoever named it necking was a poor judge of anatomy.
-- Groucho Marx
OPENED，CLOSED，ERROR = range（3）
object.state = OPENED
OPENED, CLOSED, ERROR = range(3)
object.state = OPENED
或者如果你想要更接近实际枚举的东西，有几个
食谱食谱。
似乎
根据收视率相当不错。
George
Or if you want something closer to real enumerations, there are several
recipes in the cookbook.
http://aspn.activestate.com/ASPN/Coo.../Recipe/413486 seems to
be pretty good according to the ratings.
George
取决于工作...如果我需要做位掩码操作，我会使用
整数标志。如果我希望符号是人类可读的，我将使用
字符串。但是Python中的所有内容都是一个对象，你可以使用
看起来合适......
因为我们处于''状态''例如，这里是一种可能的状态模式
实现：
类MyObject（对象）：
def __init __（self，姓名）：
self.name = name
self .__ class__ = ClosedState
state = property（fget = lambda self： self .__ class__）
def open（self，arg）：
如果arg == 1：
self .__ class__ = OpenedState
else：
self .__ class__ = ErrorState
def close（self）：
self .__ class__ = ClosedState
class OpenedState（MyObject）：pass
class ClosedState（MyObject）：pass
class ErrorState（MyObject）：pass
m = MyObject（''toto''）
断言m.state是ClosedState
m.open（1）
断言m.state是OpenedState
m.close（）
断言m .state是ClosedState
m.open（2）
断言m.state是错误状态
我做了状态''假的''对象，但是你可以通过在基类中定义默认方法和/或
覆盖''state''子类中的适当方法来使这成为一个真正的状态
模式实现。
HTH
-
bruno desthuilliers
python -c" print'' @''。join（[''。''。join（[w [:: - 1] for p in p.split（''。''）]）for
p in'' o **** @ xiludom.gro''。split（'''''）]）"
Depends on the job... If I need to do bitmask operations, I''ll use
integer flags. If I want the symbol to be human-readable, I''ll use
strings. But everything in Python being an object, you can use whatever
seems appropriate....
Since we''re in a ''state'' exemple, here''s a possible state pattern
implementation:
class MyObject(object):
def __init__(self, name):
self.name = name
self.__class__ = ClosedState
state = property(fget=lambda self: self.__class__)
def open(self, arg):
if arg == 1:
self.__class__ = OpenedState
else:
self.__class__ = ErrorState
def close(self):
self.__class__ = ClosedState
class OpenedState(MyObject):pass
class ClosedState(MyObject):pass
class ErrorState(MyObject):pass
m = MyObject(''toto'')
assert m.state is ClosedState
m.open(1)
assert m.state is OpenedState
m.close()
assert m.state is ClosedState
m.open(2)
assert m.state is ErrorState
I made states ''dummy'' objects, but you could make this a real state
pattern implementation by defining default methods in the base class and
overriding appropriate methods in the ''state'' subclasses.
HTH
--
bruno desthuilliers
python -c "print ''@''.join([''.''.join([w[::-1] for w in p.split(''.'')]) for
p in ''o****@xiludom.gro''.split(''@'')])"
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