功能類或模組。名稱

函式，類或模組的特殊屬性 __name__ 是包含其名稱的字串。

import os

class C:
    pass

def f(x):
    x += 2
    return x

print(f)
# <function f at 0x029976B0>
print(f.__name__)
# f

print(C)
# <class '__main__.C'>
print(C.__name__)
# C

print(os)
# <module 'os' from '/spam/eggs/'>
print(os.__name__)
# os

但是，__name__ 屬性不是引用類，方法或函式的變數的名稱，而是定義時賦予它的名稱。

def f():
    pass

print(f.__name__)
# f - as expected

g = f
print(g.__name__)
# f - even though the variable is named g, the function is still named f

除其他外，這可以用於除錯：

def enter_exit_info(func):
    def wrapper(*arg, **kw):
        print '-- entering', func.__name__
        res = func(*arg, **kw)
        print '-- exiting', func.__name__
        return res
    return wrapper

@enter_exit_info
def f(x):
    print 'In:', x
    res = x + 2
    print 'Out:', res
    return res

a = f(2)

# Outputs:
#     -- entering f
#     In: 2
#     Out: 4
#     -- exiting f