# 获取客户端cookie以实现登陆时问候用户功能
@route('/hello')
def hello():
  name = request.cookie.username or 'Guest'
  return template('Hello {{name}}', name=name)
 
# 获取形如/forum?id=1&page=5的查询字符串中id和page变量的值
route('/forum')
def display_forum():
  forum_id = request.query.id
  page = request.query.page or '1'
  return template('Forum ID: {{id}} (page {{page}})', id=forum_id, page=page)

class DictProperty(object):
  """ Property that maps to a key in a local dict-like attribute. """
  def __init__(self, attr, key=None, read_only=False):
    self.attr, self.key, self.read_only = attr, key, read_only
  def __call__(self, func):
    functools.update_wrapper(self, func, updated=[])
    self.getter, self.key = func, self.key or func.__name__
    return self
  def __get__(self, obj, cls):
    if obj is None: return self
    key, storage = self.key, getattr(obj, self.attr)
    if key not in storage: storage[key] = self.getter(obj)
    return storage[key]
  def __set__(self, obj, value):
    if self.read_only: raise AttributeError("Read-Only property.")
    getattr(obj, self.attr)[self.key] = value
  def __delete__(self, obj):
    if self.read_only: raise AttributeError("Read-Only property.")
    del getattr(obj, self.attr)[self.key]
class Request:
  def __init__(self, environ=None):
    self.environ {} if environ is None else envrion
    self.envrion['bottle.request'] = self
  @DictProperty('environ', 'bottle.request.query', read_only=True)
  def query(self):
    get = self.environ['bottle.get'] = FormsDict()
    pairs = _parse_qsl(self.environ.get('QUERY_STRING', ''))
    for key, value in pairs:
      get[key] = value
    return get

# version 1
class Request:
  """
  some codes here
  """
  def query(self):
    get = self.environ['bottle.get'] = FormsDict()
    pairs = _parse_qsl(self.environ.get('QUERY_STRING', ''))
    for key, value in pairs:
      get[key] = value
    return get

# 获取id
request.query().id
# 获取page
request.query().page

# query method version 2
class Request:
  """
  some codes here
  """
  @property
  def query(self):
    if 'bootle.get.query' not in self.environ:
      get = self.environ['bottle.get'] = FormsDict()
      pairs = _parse_qsl(self.environ.get('QUERY_STRING', ''))
      for key, value in pairs:
        get[key] = value
    return self.environ['bottle.get.query']

>>> AttributeError: can't set attribute

>>> AttributeError: Read-only property

# query method version 3
class Descriptor:
  def __init__(self, attr, key, getter, read_only=False):
    self.attr = attr
    self.key = key
    self.getter = getter
    self.read_only = read_only
  def __set__(self, obj, value):
    if self.read_only:
        raise AttributeError('Read only property.')
    getattr(obj, self.attr)[self.key] = value
  def __get__(self, obj, cls):
    if obj is None:
      return self
    key, storage = self.key, getattr(obj, self.attr)
    if key not in storage:
      storage[key] = self.getter(obj)
    return storage[key]
  def __delete__(self, obj):
    if self.read_only:
      raise AttributeError('Read only property.')
    del getattr(obj, self.attr)[self.key]
class Reqeust:
  """
  some codes
  """
  def query(self):
    get = self.environ['bottle.get'] = FormsDict()
    pairs = _parse_qsl(self.environ.get('QUERY_STRING', ''))
    for key, value in pairs:
      get[key] = value
    return get 
  query = Descriptor('environ', 'bottle.get.query', query, read_only=True)

key, storage = self.key, getattr(obj, self.attr)
# key='bottle.get.query'
# storage = environ 即包含HTTP请求的信息的environ
 
# 判断envrion中是否包含key来决定是否需要解析
if key not in storage:
  storage[key] = self.getter(obj)
  # self.getter(obj)就是调用了原来的query方法，不过要传入一个Request实例，也就是obj
return storage[key]

query = Descriptor('envrion', 'bottle.get.query', query, read_only=True)

class DictProperty(object):
  """ Property that maps to a key in a local dict-like attribute. """
  def __init__(self, attr, key=None, read_only=False):
    self.attr, self.key, self.read_only = attr, key, read_only
  def __call__(self, func):
    functools.update_wrapper(self, func, updated=[])
    self.getter, self.key = func, self.key or func.__name__
    return self
  def __get__(self, obj, cls):
    if obj is None: return self
    key, storage = self.key, getattr(obj, self.attr)
    if key not in storage: storage[key] = self.getter(obj)
    return storage[key]
  def __set__(self, obj, value):
    if self.read_only: raise AttributeError("Read-Only property.")
    getattr(obj, self.attr)[self.key] = value
  def __delete__(self, obj):
    if self.read_only: raise AttributeError("Read-Only property.")
    del getattr(obj, self.attr)[self.key]

@DictProperty('environ', 'bottle.get.query', read_only=True)
def query(self):
  """ some codes """

property = DictProperty('environ', 'bottle.get.query', read_only=True)
@property
def query(self):
  """ some codes """

def query(self):
  """ some codes """
 
property = DictProperty('environ', 'bottle.get.query', read_only=True)
query = property(query) # @实现的语法糖

def query(self):
  """ some codes """
 
query = DictProperty('environ', 'bottle.get.query', read_only=True)(query)

def query(self):
  """ some codes """
 
query = Descriptor('environ', 'bottle.get.query', query, read_only=True)