.. currentmodule:: aiohttp

.. _aiohttp-structures:

Common data structures

Common data structures used by aiohttp internally.

FrozenList

A list-like structure which implements :class:collections.abc.MutableSequence.

The list is mutable unless :meth:FrozenList.freeze is called, after that the list modification raises :exc:RuntimeError.

.. class:: FrozenList(items)

Construct a new non-frozen list from items iterable.

The list implements all :class:collections.abc.MutableSequence methods plus two additional APIs.

.. attribute:: frozen

  A read-only property, ``True`` is the list is *frozen*
  (modifications are forbidden).

.. method:: freeze()

  Freeze the list. There is no way to *thaw* it back.

ChainMapProxy

An immutable version of :class:collections.ChainMap. Internally the proxy is a list of mappings (dictionaries), if the requested key is not present in the first mapping the second is looked up and so on.

The class supports :class:collections.abc.Mapping interface.

.. class:: ChainMapProxy(maps)

Create a new chained mapping proxy from a list of mappings (maps).

.. versionadded:: 3.2