如何使用带有函数名称的字符串调用函数?例如:

import foo
func_name = "bar"
call(foo, func_name)  # calls foo.bar()

当前回答

这是一个简单的答案,例如,这将允许您清除屏幕。下面有两个示例,分别是eval和exec,它们将在清理后在顶部打印0(如果您使用的是Windows,请将clear更改为cls,例如,Linux和Mac用户保持原样)或仅执行它。

eval("os.system(\"clear\")")
exec("os.system(\"clear\")")

其他回答

值得一提的是,如果您需要将函数(或类)名称和应用程序名称作为字符串传递,那么可以这样做:

myFnName  = "MyFn"
myAppName = "MyApp"
app = sys.modules[myAppName]
fn  = getattr(app,myFnName)

还没有人提到operator.attrgetter:

>>> from operator import attrgetter
>>> l = [1, 2, 3]
>>> attrgetter('reverse')(l)()
>>> l
[3, 2, 1]
>>> 

在python3中,可以使用__getattribute__方法。请参见以下列表方法名称字符串示例:

func_name = 'reverse'

l = [1, 2, 3, 4]
print(l)
>> [1, 2, 3, 4]

l.__getattribute__(func_name)()
print(l)
>> [4, 3, 2, 1]

虽然getattr()是一种优雅的(大约快7倍)方法,但您可以使用eval从函数(local、class方法、模块)获得返回值,其优雅程度与x=eval('fo.bar')()相同。当您实现一些错误处理时,就会非常安全(getattr也可以使用相同的原理)。模块导入和类示例:

# import module, call module function, pass parameters and print retured value with eval():
import random
bar = 'random.randint'
randint = eval(bar)(0,100)
print(randint) # will print random int from <0;100)

# also class method returning (or not) value(s) can be used with eval: 
class Say:
    def say(something='nothing'):
        return something

bar = 'Say.say'
print(eval(bar)('nice to meet you too')) # will print 'nice to meet you' 

当模块或类不存在(键入错误或其他更好的错误)时,就会引发NameError。如果函数不存在,则引发AttributeError。这可用于处理错误:

# try/except block can be used to catch both errors
try:
    eval('Say.talk')() # raises AttributeError because function does not exist
    eval('Says.say')() # raises NameError because the class does not exist
    # or the same with getattr:
    getattr(Say, 'talk')() # raises AttributeError
    getattr(Says, 'say')() # raises NameError
except AttributeError:
    # do domething or just...
    print('Function does not exist')
except NameError:
    # do domething or just...
    print('Module does not exist')

getattr根据对象的名称调用方法。但此对象应该是调用类的父对象。父类可以由super(self.__class__,self)获取

class Base:
    def call_base(func):
        """This does not work"""
        def new_func(self, *args, **kwargs):
            name = func.__name__
            getattr(super(self.__class__, self), name)(*args, **kwargs)
        return new_func

    def f(self, *args):
        print(f"BASE method invoked.")

    def g(self, *args):
        print(f"BASE method invoked.")

class Inherit(Base):
    @Base.call_base
    def f(self, *args):
        """function body will be ignored by the decorator."""
        pass

    @Base.call_base
    def g(self, *args):
        """function body will be ignored by the decorator."""
        pass

Inherit().f() # The goal is to print "BASE method invoked."