str對象不可調用錯誤python

Question

我一直在嘗試在Python中運行以下代碼：

def likes(names):
    dictionary_of_sizes = {
        0:"no one likes this", 
        1:(lambda names: "{} likes this".format(names[0])),
        2:(lambda names: "{} and {} like this".format(names[0], names[1])),
        3:(lambda names: "{}, {} and {} like this".format(name[0], names[1],names[2])),
        4:(lambda names: "{}, {} and {} others like this".format(names[0], names[1], len(names)-2))
    }
    return dictionary_of_sizes[len(names)](names) if len(names)<4 else dictionary_of_sizes[4]

我總是得到錯誤的'str'對象不可調用。

問題：我做錯了什么？

Answer 1

如果傳遞一個空字符串，它將寫出錯誤消息。 您可以使用列表而不是字典：

def likes(names):
    options = ["no one likes this", 
                lambda names: "{} likes this".format(names[0]),
                lambda names: "{} and {} like this".format(names[0], names[1]),
                lambda names: "{}, {} and {} like this".format(name[0], names[1],names[2]),
                lambda names: "{}, {} and {} others like this".format(names[0], names[1], len(names)-2)
            ]
    if type(names) == list:
        return options[min(len(options),len(names))](names)

使用Python 3.6的f字符串：

def likes(names):
    options = [ lambda:"no one likes this", 
                lambda:f"{names[0]} likes this",
                lambda:f"{names[0]} and {names[1]} like this",
                lambda:f"{names[0]}, {names[1]} and {names[2]} like this",
                lambda:f"{names[0]}, {names[1]} and {len(names)-2} others like this"
            ]
    return options[min(len(options),len(names))]()


print(likes([]))
print(likes("bob"))
print(likes([""]))
print(likes(["alice","bob"]))
print(likes(["alice","bob","charlie"]))
print(likes(["alice","bob","charlie","david"]))

輸出：

no one likes this
no one likes this
b, o and b like this
 likes this
alice and bob like this
alice, bob and charlie like this
alice, bob and 2 others like this

Answer 2

您沒有向我們展示引發異常的代碼。 當您不告訴我們您在做什么時，很難說您在做什么錯。 但是，如果我這樣做，它似乎可以工作：

>>> likes(["John","Harry"])
'John and Harry like this'

我懷疑您可能會這樣調用likes() ：

>>> likes(["John","Harry"])()
Traceback (most recent call last):
  File "<input>", line 1, in <module>
TypeError: 'str' object is not callable

或像這樣：

>>> likes("")
Traceback (most recent call last):
  File "<input>", line 1, in <module>
  File "<input>", line 7, in likes
TypeError: 'str' object is not callable

毫不奇怪，您很難確定如何調用該函數。 該代碼的作用是不必要的復雜。 它需要完全重寫。 如果要快速修復，請更改此行：

{0:"no one likes this", 

至

{0:(lambda names: "no one likes this"),

但是，您實際上應該刪除所有那些不必要且難以閱讀的lambda並執行以下操作：

def likes(names):
    if len(names) > 3:
        names = names[:2] + [f"{len(names)-2} others"]
    elif len(names) == 0:
        names = ["no-one"]
    result = " and ".join(", ".join(names).rsplit(", ",1))
    if len(names) == 1:
        return result + " likes this"
    else:
        return result + " like this"