python - 如何在给定指针的情况下获取函数的名称和/或描述

Question

我正在使用 Python 2.7。有没有办法将名称、描述和可能的其他元数据与函数相关联，这样我就不必使用外部字典来保存此类信息，如下面的代码所示:

def predicateA(v):
    # some logic that eventually returns a True/False value
    return True

def predicateB(v):
    # some logic that eventually returns a True/False value
    return False

predicateNames={}
predicateNames[predicateA]='name and description for predicateA'
predicateNames[predicateB]='name and description for predicateB'

predicates = [predicateA, predicateB]

def evalForAllPredicates(v):
    for f in predicates:
       result = f(v)
       print "function %s returned: %s" % (predicateNames[f], result)

evalForAllPredicates(3)

Answer 1

您可以通过 __name__ 和 __doc__ 属性访问函数的名称及其文档字符串。函数的文档字符串只是作为函数中第一条语句放置的字符串文字。约定是使用三重引号将文档字符串括起来，因为它们预计会跨越多行。

def predicateA(v):
    """
    some logic that eventually returns a True/False value
    """
    return True

print "Name:", predicateA.__name__
print "Doc:", predicateB.__doc__

要将任意元数据关联到一个函数，只需将您喜欢的任何属性分配给该函数，就好像它是一个普通对象一样，毕竟它就是一个普通对象。

def predicateB(v):
    """
    some logic that eventually returns a True/False value
    """
    return False

predicateA.alwaysReturnsFalse = False
predicateB.alwaysReturnsFalse = True

for pred in [predicateA, predicateB]:
    print "Function:", pred.__name__
    print "Documentation:", pred.__doc__
    if pred.alwaysReturnsFalse:
        print "(This function always returns false)"

Function: predicateADocumentation:    some logic that eventually returns a True/False valueFunction: predicateBDocumentation:    some logic that eventually returns a True/False value(This function always returns false)