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PEP 416: Add links to existing implementations

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Victor Stinner 2012-03-14 23:18:49 +01:00
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@ -125,6 +125,38 @@ However dictproxy can be useful in some cases, where its mutable property is
not an issue, to avoid a copy of the dictionary.
Existing implementations
========================
Whitelist approach.
* `Implementing an Immutable Dictionary (Python recipe 498072)
<http://code.activestate.com/recipes/498072/>`_ by Aristotelis Mikropoulos.
Similar to frozendict except that it is not truly read-only: it is possible
to access to this private internal dict. It does not implement __hash__ and
has an implementation issue: it is possible to call again __init__() to
modify the mapping.
* PyWebmail contains an ImmutableDict type: `webmail.utils.ImmutableDict
<http://pywebmail.cvs.sourceforge.net/viewvc/pywebmail/webmail/webmail/utils/ImmutableDict.py?view=markup>`_.
It is hashable if keys and values are hashable. It is not truly read-only:
its internal dict is a public attribute.
Blacklist approach: inherit from dict and override write methods to raise an
exception. It is not truly read-only: it is still possible to call dict methods
on such "frozen dictionary" to modify it.
* brownie: `brownie.datastructures.ImmuatableDict
<https://github.com/DasIch/brownie/blob/HEAD/brownie/datastructures/mappings.py>`_.
It is hashable if keys and values are hashable. werkzeug project has the
same code: `werkzeug.datastructures.ImmutableDict
<https://github.com/mitsuhiko/werkzeug/blob/master/werkzeug/datastructures.py>`_.
* SQLAchemy project: `sqlachemy.util.immutabledict
<http://hg.sqlalchemy.org/sqlalchemy/file/tip/lib/sqlalchemy/util/_collections.py>`_.
It is not hashable and has an extra method: union().
* `Frozen dictionaries (Python recipe 414283) <http://code.activestate.com/recipes/414283/>`_
by Oren Tirosh. It is hashable if keys and values are hashable.
Links
=====
@ -133,16 +165,8 @@ Links
* PEP 412: Key-Sharing Dictionary
(`issue #13903 <http://bugs.python.org/issue13903>`_)
* PEP 351: The freeze protocol
* `The case for immutable dictionaries; and the central misunderstanding of PEP 351 <http://www.cs.toronto.edu/~tijmen/programming/immutableDictionaries.html>`_
* `Frozen dictionaries (Python recipe 414283) <http://code.activestate.com/recipes/414283/>`_
by Oren Tirosh. Blacklist approach: inherit from dict and override write
methods to raise an exception. It is not truly read-only: it is still
possible to call dict methods on such "frozen dictionary" to modify it.
* `Implementing an Immutable Dictionary (Python recipe 498072) <http://code.activestate.com/recipes/498072/>`_
by Aristotelis Mikropoulos. Similar to frozendict except that it is not
truly read-only. It is possible to access to this private internal dict.
It does not implement __hash__ and has an implementation issue: it is
possible to call again __init__() to modify the mapping.
* `The case for immutable dictionaries; and the central misunderstanding of
PEP 351 <http://www.cs.toronto.edu/~tijmen/programming/immutableDictionaries.html>`_
* `make dictproxy object via ctypes.pythonapi and type() (Python recipe
576540) <http://code.activestate.com/recipes/576540/>`_ by Ikkei Shimomura.
* Python security modules implementing read-only object proxies using a C