__all__ = ['cacheable', 'callable_find_by', 'property_find_by']
def cacheable_decorator(lookup):
  def func(self):
    if not hasattr(self, '_elements_cache'):
      self._elements_cache = {} # {callable_id: element(s)}
    cache = self._elements_cache

    key = id(lookup)
    if key not in cache:
      cache[key] = lookup(self)
    return cache[key]
  return func
cacheable = cacheable_decorator

_strategy_kwargs = ['id_', 'xpath', 'link_text', 'partial_link_text',
          'name', 'tag_name', 'class_name', 'css_selector']

def _callable_find_by(how, using, multiple, cacheable, context, driver_attr, **kwargs):
  def func(self):
    # context - driver or a certain element
    if context:
      ctx = context() if callable(context) else context.__get__(self) # or property
    else:
      ctx = getattr(self, driver_attr)

    # 'how' AND 'using' take precedence over keyword arguments
    if how and using:
      lookup = ctx.find_elements if multiple else ctx.find_element
      return lookup(how, using)

    if len(kwargs) != 1 or list(kwargs.keys())[0] not in _strategy_kwargs:
      raise ValueError(
        "If 'how' AND 'using' are not specified, one and only one of the following "
        "valid keyword arguments should be provided: %s." % _strategy_kwargs)

    key = list(kwargs.keys())[0];
    value = kwargs[key]
    suffix = key[:-1] if key.endswith('_') else key # find_element(s)_by_xxx
    prefix = 'find_elements_by' if multiple else 'find_element_by'
    lookup = getattr(ctx, '%s_%s' % (prefix, suffix))
    return lookup(value)

  return cacheable_decorator(func) if cacheable else func
def callable_find_by(how=None, using=None, multiple=False, cacheable=False, context=None, driver_attr='_driver',
           **kwargs):
  return _callable_find_by(how, using, multiple, cacheable, context, driver_attr, **kwargs)


def property_find_by(how=None, using=None, multiple=False, cacheable=False, context=None, driver_attr='_driver',
           **kwargs):
  return property(_callable_find_by(how, using, multiple, cacheable, context, driver_attr, **kwargs))

from pageobject_support import callable_find_by as by
from selenium import webdriver
from time import sleep
class BaiduSearchPage(object):
  def __init__(self, driver):
    self._driver = driver #初始化浏览器的api
  search_box = by(id_="kw")
  search_button = by(id_='su')
  def search(self, keywords):
    self.search_box().clear()
    self.search_box().send_keys(keywords)
    self.search_button().click()