如何检查函数是否用特定的装饰器装饰?

我想检查Python函数是否经过修饰,并将decorator参数存储在函数dict中。这是我的代码:

from functools import wraps

def applies_to(segment="all"):
    def applies(func):
        @wraps(func)
        def wrapper(*args, **kwargs):
            func.func_dict["segment"] = segment
            print func.__name__
            print func.func_dict
            return func(*args, **kwargs)
        return wrapper
    return applies

@applies_to(segment="mysegment")
def foo():
    print "Some function"


> foo() # --> Ok, I get the expected result
foo
{'segment': 'mysegment'}

> foo.__dict__ # --> Here I get empty result. Why is the dict empty?
{}