##
11.20.1 CookieJar and FileCookieJar Objects

`CookieJar` objects support the iterator protocol for iterating over contained `Cookie` objects.

`CookieJar` has the following methods:

`add_cookie_header`( | request)

  Add correct Cookie: header to request.

  If policy allows (ie. the `rfc2965` and `hide_cookie2` attributes of the `CookieJar`'s `CookiePolicy` instance are true and false respectively), the Cookie2: header is also added when appropriate.

  The request object (usually a `urllib2.Request` instance) must support the methods `get_full_url()`, `get_host()`, `get_type()`, `unverifiable()`, `get_origin_req_host()`, `has_header()`, `get_header()`, `header_items()`, and `add_unredirected_header()`,as documented by `urllib2`.

`extract_cookies`( | response, request)

  Extract cookies from HTTP response and store them in the `CookieJar`, where allowed by policy.

  The `CookieJar` will look for allowable Set-Cookie: and Set-Cookie2: headers in the response argument, and store cookies as appropriate (subject to the `CookiePolicy.set_ok()` method's approval).

  The response object (usually the result of a call to `urllib2.urlopen()`, or similar) should support an `info()` method, which returns an object with a `getallmatchingheaders()` method (usually a `mimetools.Message` instance).

  The request object (usually a `urllib2.Request` instance) must support the methods `get_full_url()`, `get_host()`, `unverifiable()`, and `get_origin_req_host()`, as documented by `urllib2`. The request is used to set default values for cookie-attributes as well as for checking that the cookie is allowed to be set.

`set_policy`( | policy)

  Set the `CookiePolicy` instance to be used.

`make_cookies`( | response, request)

  Return sequence of `Cookie` objects extracted from response object.

  See the documentation for `extract_cookies` for the interfaces required of the response and request arguments.

`set_cookie_if_ok`( | cookie, request)

  Set a `Cookie` if policy says it's OK to do so.

`set_cookie`( | cookie)

  Set a `Cookie`, without checking with policy to see whether or not it should be set.

`clear`( | [domain[, path[, name]]])

  Clear some cookies.

  If invoked without arguments, clear all cookies. If given a single argument, only cookies belonging to that domain will be removed. If given two arguments, cookies belonging to the specified domain and URL path are removed. If given three arguments, then the cookie with the specified domain, path and name is removed.

  Raises `KeyError` if no matching cookie exists.

`clear_session_cookies`( | )

  Discard all session cookies.

  Discards all contained cookies that have a true `discard` attribute (usually because they had either no `max-age` or `expires` cookie-attribute, or an explicit `discard` cookie-attribute). For interactive browsers, the end of a session usually corresponds to closing the browser window.

  Note that the `save()` method won't save session cookies anyway, unless you ask otherwise by passing a true ignore_discard argument.

`FileCookieJar` implements the following additional methods:

`save`( | filename=`None`, ignore_discard=`False`, ignore_expires=`False`)

  Save cookies to a file.

  This base class raises `NotImplementedError`. Subclasses may leave this method unimplemented.

  filename is the name of file in which to save cookies. If filename is not specified, `self.filename` is used (whose default is the value passed to the constructor, if any); if `self.filename` is `None`, `ValueError` is raised.

  ignore_discard: save even cookies set to be discarded. ignore_expires: save even cookies that have expired

  The file is overwritten if it already exists, thus wiping all the cookies it contains. Saved cookies can be restored later using the `load()` or `revert()` methods.

`load`( | filename=`None`, ignore_discard=`False`, ignore_expires=`False`)

  Load cookies from a file.

  Old cookies are kept unless overwritten by newly loaded ones.

  Arguments are as for `save()`.

  The named file must be in the format understood by the class, or `LoadError` will be raised.

`revert`( | filename=`None`, ignore_discard=`False`, ignore_expires=`False`)

  Clear all cookies and reload cookies from a saved file.

  Raises `cookielib.LoadError` or `IOError` if reversion is not successful; the object's state will not be altered if this happens.

`FileCookieJar` instances have the following public attributes:

`filename`
  Filename of default file in which to keep cookies. This attribute may be assigned to.

`delayload`
  If true, load cookies lazily from disk. This attribute should not be assigned to. This is only a hint, since this only affects performance, not behaviour (unless the cookies on disk are changing). A `CookieJar` object may ignore it. None of the `FileCookieJar` classes included in the standard library lazily loads cookies.