python - 赋值之前引用的局部变量/Python

Question

我正在尝试设计一个计数器，每次执行操作时该计数器都会增加。像这样:

def action_on_accounts(self, accounts):
    for account in accounts[9:]: 
        try:
            self.browser.get(account)
            time.sleep(5)
            action_button = self.browser.find_element_by_xpath(u'//button[contains(@class, "Heart")]').click()
            counter_var = self.count_actions(counter_var)
            print(counter_var)
        except selenium.common.exceptions.NoSuchElementException:
            break

def count_actions(self, counter_var):
    return counter_var + 1

def main(self):

    counter_var = 0
    (...)

这是抛出一个 UnboundLocalError: local variable 'counter_var' referenced before assignment
我读过我必须将 counter_var声明为全局内部函数，并执行以下操作:

def count_actions(self, counter_var):
    global counter_var
    return counter_var + 1

它正在抛出 SyntaxError: name 'counter_var' is parameter and global error。

所以我尝试了这个:

def count_actions(self):
    global counter_var
    return counter_var + 1

这样调用:

counter_var = self.count_actions()
print(counter_var)

现在我有了 NameError: name 'counter_var' is not defined...。

请协助

Answer 1

您应该考虑将counter_var定义为属性:self.counter_var。在整个类(class)中都可以访问它(假设正在发生这种情况)。您无需在函数/方法中显式提供它作为参数，也不必担心全局变量。

def action_on_accounts(self, accounts):
    for account in accounts[9:]: 
        try:
            self.browser.get(account)
            time.sleep(5)
            action_button = self.browser.find_element_by_xpath(u'//button[contains(@class, "Heart")]').click()
            self.count_actions()
            print(self.counter_var)
        except selenium.common.exceptions.NoSuchElementException:
            break

def count_actions(self):
    self.counter_var += 1

def main(self):

    self.counter_var = 0
    (...)

但是，您可能想用您的类初始化 self.counter_var。