python - 如何从Python中的__new__构造函数调用方法？

Question

我试图在 __new__ 方法中调用 get_driver_path，当我尝试运行完整代码时出现此错误:

TypeError: unbound method get_chrome_driver() must be called with
WebBrowserManager instance as first argument (got str instance instead

这是代码:

def __new__(self, driver = 'firefox'):
    if not self._instance:
        self._instance = super(WebBrowserManager, self).__new__(self)
        self._profile.native_events_enabled = True
        self.data = {}
        self._system = platform.system()
        if self._local:
            if driver == 'firefox':
                self.browser = webdriver.Firefox(self._profile)
            elif driver == 'chrome':
                self.browser = self.get_chrome_driver(self._system, driver)
            elif driver == 'ie':
                assert self._system == 'Windows', 'Tests on Internet Explorer are only supported on Windows'
                self.browser = webdriver.Ie(self.get_driver_path(driver))
    return self._instance

def get_driver_path(self, driver):
    driver_name = ''
    if driver == 'ie':
        driver_name = 'IEDriverServer.exe'
    elif driver == 'chrome':
       driver_name = 'chromedriver.exe'
    driver_path = "selenium_drivers\\" + driver_name 
    os.environ["webdriver." + driver + ".driver"] = driver_path
    return driver_path

Answer 1

由于您将其设为实例方法，因此您需要在 __new__ 方法中创建的实例上调用它(该方法是静态的；例如，未绑定(bind)到实例或类):

self.browser = webdriver.Ie(self._instance.get_driver_path(driver))

您可以将该方法设置为静态方法或类方法，此时您可以通过 __new__ 的第一个参数来使用它(这是类，而不是实例；通常您不会使用名称 self 但改为 cls):

@staticmethod
def get_driver_path(driver):

请注意，staticmethod 不会采用 self 参数，但您的 get_driver_path() 实现无论如何也不会使用该参数。