Question

在Python中如何编写这样一个函数，它将使用给定的前缀调用当前文件中的所有函数？

例如：

def prepare(self):
  # ??? to call prepare_1, prepare_2

def prepare_1(self):

def prepare_2(self):

如何编写prepare以便它会调用以prepare_开头的所有函数？

Answer 1

使用globals访问全局命名空间，dict.items迭代它，callable和str.startswith以确定该函数具有您希望的名称并且可以调用：

def prepare(self):
  for key, value in globals().items():
      if callable(value) and key.startswith('prepare_'):
          value()

def prepare_1(self):print 1

def prepare_2(self):print 2

Answer 2

如果这些函数是类的方法，请使用dir(self)列出self的所有属性。

class C:

    def prepare(self):
        print(dir(self))
        for name in dir(self):
            if name.startswith('prepare_'):
                method = getattr(self, name)
                method()

    def prepare_1(self):
        print('In prepare_1')

    def prepare_2(self):
        print('In prepare_2')

C().prepare()

输出：

['__class__', '__delattr__', '__dict__', '__dir__', '__doc__', '__eq__', '__format__', '__ge__', '__getattribute__', '__gt__', '__hash__', '__init__', '__le__', '__lt__', '__module__', '__ne__', '__new__', '__reduce__', '__reduce_ex__', '__repr__', '__setattr__', '__sizeof__', '__str__', '__subclasshook__', '__weakref__', 'prepare', 'prepare_1', 'prepare_2']
In prepare_1
In prepare_2

更新：如果你想调用C类以外的方法：

obj = C()
for name in dir(obj):
    if name.startswith('prepare_'):
        m = getattr(obj, name)
        print(m)
        m()

输出：

<bound method C.prepare_1 of <__main__.C object at 0x7f347c9dff28>>
In prepare_1
<bound method C.prepare_2 of <__main__.C object at 0x7f347c9dff28>>
In prepare_2

Answer 3

有人要求，所以这是一个快速的黑客攻击：

import functools

class FunctionGroup(object):
   """
       Defines a function group as a list of functions that can be
       executed sequentially from a single call to the function group.

       Use
       @func_group.add
       def my_func(...):
           ...

       to add functions to the function group.

       `func_group(...)` calls the added functions one by one.

       It returns a list of the return values from all evaluated functions.

       Processing terminates when one of the function raises an
       exception and the exception is propagated to the caller.
    """
    def __init__(self):
        self.funcs = []

    def add(self, func):
        self.funcs.append(func)
        return func

    def __call__(self, *args, **kwargs):
        return [
            func(*args, **kwargs) for func in self.funcs
        ]


prepare_group = FunctionGroup()

请注意，__call__()实现相当原始，无法处理异常。

用法示例：

@prepare_group.add
def prepare_1():
    print "prep 1"

@prepare_group.add
def prepare_2():
    print "prep 2"

prepare_group()

当然可能滥用来调用方法：

class C(object):
    def m(self):
       pass
c = C()
func_group.add(c.m)

如何调用名称以给定前缀开头的所有函数？

3 个答案: