Python 向以前定义的函数添加功能的优雅方式 如何将两个功能结合在一起
我有一个类控制一些硬件：Python 向以前定义的函数添加功能的优雅方式 如何将两个功能结合在一起,python,decorator,Python,Decorator,我有一个类控制一些硬件： class Heater() def set_power(self,dutycycle, period) ... def turn_on(self) ... def turn_off(self) 以及一个连接到数据库并处理实验的所有数据记录功能的类： class DataLogger() def __init__(self) # Record measurements and controls
class Heater()
def set_power(self,dutycycle, period)
...
def turn_on(self)
...
def turn_off(self)
class DataLogger()
def __init__(self)
# Record measurements and controls in a database
def start(self,t)
# Starts a new thread to acquire and record measuements every t seconds
log = DataLogger()
@DataLogger_decorator
H1 = Heater()
log.start(60)
H1.set_power(10,100)
H1.turn_on()
sleep(10)
H1.turn_off()
etc
其中H1上的所有操作都由数据记录器记录。我可以改变任何涉及的类，只是寻找一种优雅的方式来做到这一点。理想情况下，硬件功能与数据库和数据记录器功能保持分离。理想情况下，数据记录器可用于其他控件和测量。对于这种情况，我更喜欢将数据记录器用作基类或混入其他类，而不是尝试执行某种装饰器魔术（这对我来说并不是一种使用装饰器的pythonic方式） e、 g: 这样你就可以做到：
h1 = Heater()
h1.startlog(5)
h1.do_other_stuff()
class DataLoggerMixin(object):
def __init__(self):
# do your init things
super(DataLogger, this).__init__() # this will trigger the next __init__ call in the inheritance chain (i.e. whatever you mix it with)
class Heater(object):
""" Here's a heater you have lying around that doesn't do data logging. No need to change it."""
# add a new child class with 2 lines, that includes the DataLoggerMixin as the first parent class, and you will have a new class with all the DataLogging functionality and the Heater functionality.
class LoggingHeater(DataLoggerMixin, Heater):
""" Now its a data logging heater """
pass # no further code should be necessary if you list DataLoggerMixin first in the base classes.
>>> logging_heater = LoggingHeater()
>>> logging_heater.start_log(5)
>>> logging_heater.do_heater_stuff()
____________________________________________________________________
class DataLogger(object)
def __init__(self, object_to_log)
self.object = object_to_log # now you have access to self.object in all your methods.
# Record measurements and controls in a database
def start(self,t)
# Starts a new thread to aqcuire and reccord measuements every t secconds
h1 = Heater()
log = DataLogger(h1)
log.start(60)
h1.set_power(10,100)
h1.turn_on()
sleep(10)
h1.turn_off()
希望这有帮助 对于这个场景，我更喜欢使用数据记录器作为基类或其他类的Mixin，而不是尝试使用某种装饰器魔术（这对我来说并不是一种使用装饰器的python方式） e、 g: 这样你就可以做到：
h1 = Heater()
h1.startlog(5)
h1.do_other_stuff()
class DataLoggerMixin(object):
def __init__(self):
# do your init things
super(DataLogger, this).__init__() # this will trigger the next __init__ call in the inheritance chain (i.e. whatever you mix it with)
class Heater(object):
""" Here's a heater you have lying around that doesn't do data logging. No need to change it."""
# add a new child class with 2 lines, that includes the DataLoggerMixin as the first parent class, and you will have a new class with all the DataLogging functionality and the Heater functionality.
class LoggingHeater(DataLoggerMixin, Heater):
""" Now its a data logging heater """
pass # no further code should be necessary if you list DataLoggerMixin first in the base classes.
>>> logging_heater = LoggingHeater()
>>> logging_heater.start_log(5)
>>> logging_heater.do_heater_stuff()
____________________________________________________________________
class DataLogger(object)
def __init__(self, object_to_log)
self.object = object_to_log # now you have access to self.object in all your methods.
# Record measurements and controls in a database
def start(self,t)
# Starts a new thread to aqcuire and reccord measuements every t secconds
h1 = Heater()
log = DataLogger(h1)
log.start(60)
h1.set_power(10,100)
h1.turn_on()
sleep(10)
h1.turn_off()
希望这有帮助 您可以装饰加热器，并向装饰者提供记录器作为参数：
# define the primitive logger
class Logger(object):
def log(self, func, args, kwargs):
print "Logging %s %r %r" % (func, args, kwargs)
# define the decorator
# since it accepts an argument, it's essentially a decorator generator
# which is supposed to return the actual decorator
# which in turn adds a logger call to each method of the class
def with_logger(logger):
def method_wrapper(cls):
def wrap(name, fun):
def _(self, *a, **kw):
logger.log(name, a, kw)
return fun(self, *a, **kw)
return _
for k in dir(cls):
v = getattr(cls, k)
if not k.startswith('__') and callable(v):
setattr(cls, k, wrap(k, v))
return cls
return method_wrapper
# create a logger...
my_logger = Logger()
# ...and pass it to the decorator
@with_logger(my_logger)
class Heater(object):
def set_power(self,dutycycle, period):
pass
def turn_on(self):
pass
def turn_off(self):
pass
# let's test!
h = Heater()
h.set_power(100, 200)
h.turn_on()
h.turn_off()
您可以装饰加热器，并将记录器作为参数提供给装饰者：
# define the primitive logger
class Logger(object):
def log(self, func, args, kwargs):
print "Logging %s %r %r" % (func, args, kwargs)
# define the decorator
# since it accepts an argument, it's essentially a decorator generator
# which is supposed to return the actual decorator
# which in turn adds a logger call to each method of the class
def with_logger(logger):
def method_wrapper(cls):
def wrap(name, fun):
def _(self, *a, **kw):
logger.log(name, a, kw)
return fun(self, *a, **kw)
return _
for k in dir(cls):
v = getattr(cls, k)
if not k.startswith('__') and callable(v):
setattr(cls, k, wrap(k, v))
return cls
return method_wrapper
# create a logger...
my_logger = Logger()
# ...and pass it to the decorator
@with_logger(my_logger)
class Heater(object):
def set_power(self,dutycycle, period):
pass
def turn_on(self):
pass
def turn_off(self):
pass
# let's test!
h = Heater()
h.set_power(100, 200)
h.turn_on()
h.turn_off()
你知道吗，
@decorator@decorator