Question

我有一个很奇怪的问题。

我需要返回一个类对象以调用应该返回调用它的类对象的函数。我知道我知道。只是将其视为人为设计的练习，尽管对我而言这是非常实际的需求。

def baz():
    # return the object instance that calls me. 

class Foo():
    def bar(self, func):
        return func()  # should return the Foo object but how???

new_foo = Foo()
new_foo_instance = new_foo.bar(baz)

是否可以在baz()中写任何东西来返回调用它的对象？

编辑：

回答评论：

我尝试使用inspect，但没有成功，甚至查看了整个堆栈，但找不到与new_foo对象匹配的条目：

new_foo如下所示：<__main__.Foo object at 0x0000029AAFC4C780>

当我打印出整个堆栈时，在其中找不到该条目：

def baz():
    print(inspect.stack())
    return inspect.stack() #[1][3]

>>> [FrameInfo(frame=<frame object at 0x0000029AADB49648>, filename='return_caller.py', lineno=5, function='baz', code_context=['    print(inspect.stack())\n'], index=0), FrameInfo(frame=<frame object at 0x0000029AAD8F0DE8>, filename='return_caller.py', lineno=11, function='bar', code_context=['        return func()  # should return the Foo object but how???\n'], index=0), FrameInfo(frame=<frame object at 0x0000029AAD8AC588>, filename='return_caller.py', lineno=19, function='<module>', code_context=['new_foo_instance = new_foo.bar(baz)\n'], index=0)]

所以我不是想让它返回新的Foo实例，而是实际上与new_foo完全相同的实例。

Answer 1

使用检查：

import inspect

def baz():
    frame_infos = inspect.stack()  # A list of FrameInfo.
    frame = frame_infos[1].frame   # The frame of the caller.
    locs = frame.f_locals          # The caller's locals dict.
    return locs['self']

class Foo():
    def bar(self, func):
        return func()

f1 = Foo()
f2 = f1.bar(baz)
print(f1)
print(f2)
print(f2 is f1)  # True

或作弊：

def baz():
    return getattr(baz, 'self', None)

class Foo():
    def bar(self, func):
        func.self = self  # Functions can be a place to store global information.
        return func()

Answer 2

以上答案很完美，这是满足您需求的另一种方法。

import sys 
import inspect

def baz():
    """
    Return the object instance whose method calls me
    """
    for item in dir(sys.modules[__name__]):
        elem = eval(item)

        if inspect.isclass(elem):
            foo_instance = elem()
            break

    return foo_instance

class Foo():
    """
    Foo class
    """
    def bar(self, func):
        return func()  # should return the Foo object but how???

# Instantiation and calling
new_foo = Foo()
new_foo_instance = new_foo.bar(baz)

print(new_foo_instance)       # <__main__.Foo object at 0x0000015C5A2F59E8>
print(type(new_foo_instance)) # <class '__main__.Fo


# E:\Users\Rishikesh\Projects\Python3\try>python Get_caller_object_final.py
# <__main__.Foo object at 0x0000015C5A2F59E8>
# <class '__main__.Foo'>

参考书目»

调用它的python独立函数返回对象实例

2 个答案: