Metadata-Version: 2.0
Name: python-disk-collections
Version: 0.0.2
Summary: Package provides classes: FileList, FileDeque that behaves like bulltins but keeps items at disk.
Home-page: https://github.com/thegrymek/python-disk-collections
Author: thegrymek
Author-email: andrzej.grymkowski@gmail.com
License: MIT
Download-URL: https://github.com/thegrymek/python-disk-collections/archive/0.0.2.tar.gz
Description-Content-Type: UNKNOWN
Keywords: pickle,cache,collections,list,deque,json,zlib
Platform: UNKNOWN
Classifier: Operating System :: OS Independent
Classifier: Programming Language :: Python :: 2.7
Classifier: Programming Language :: Python :: 3.4
Classifier: Programming Language :: Python :: 3.5
Classifier: Programming Language :: Python :: 3.6
Classifier: Topic :: Software Development :: Libraries :: Python Modules

=======================
Python Disk Collections
=======================

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Module contains class with extended python list that stores items at disk.
By default items before save are pickled and compressed. Use that list
as usual list!

In addition, there is implemented extended python deque with disk storage and
same behaviour as **collections.deque**.

Intend of package was to create generic iterables that stores really big collection of items
that does not fit in memory and to avoid usage of external cache and local database
storages.


.. code-block:: python

    >>> from diskcollections.iterables import FileList
    >>> flist = FileList()
    >>> flist.extend([1, 2, 3])
    >>> flist.append(4)
    >>> flist
    [1, 2, 3, 4]
    >>> flist[2]
    3
    >>> flist2 = flist[:]  # copy makes new FileList
    >>> my_list = list(flist)  # now its simple list


.. code-block:: python

    >>> from diskcollections.iterables import FileQueue
    >>> fdeque = FileQueue()
    >>> fdeque.extend([1, 2, 3])
    >>> fdeque.append(4)
    >>> fdeque
    FileDeque([1, 2, 3, 4])
    >>> fdeque.pop()
    4
    >>> fdeque.appendleft(0)
    >>> fdeque.popleft()
    0


There are available more ways to serialize items.


.. code-block:: python

    >>> from diskcollections.iterables import FileList, FileDeque
    >>> from diskcollections.handlers import (
        PickleHandler,  # pickle items
        PickleZLibHandler,  # pickle + compress items
        JsonHandler, # convert to json items
        JsonZLibHandler  # convert to json + compress items
    )
    >>> from functools import partial
    >>> JsonFileList = partial(FileList, handler_class=JsonHandler)
    >>> flist = JsonFileList()
    >>> flist.append({'a': 1, 'b': 2, 'c': 3})
    >>> flist[0]
    {u'a': 1, u'b': 2, u'c': 3}


Installation
------------

To install package type

.. code-block:: bash

    $ pip install python-disk-collections


How it works
------------

In order to implement your serializer create class with methods:
**dumps** and **loads** or import interface.


.. code-block:: python

    >>> from diskcollections.interfaces import IHandler

    class IHandler:

    @staticmethod
    def dumps(obj):
        """Converts object to string.

        :param obj: any python object
        :return: dumped string
        """
        raise NotImplementedError

    @staticmethod
    def loads(obj):
        """Restored dumped string into python object.

        :param obj: Object stored as string
        :return: python object restored from dump
        """
        raise NotImplementedError

All handlers from example above implements interface **IHandler**.

Under the hood, **FileList** for storage items uses *tempfile.mktemp* (in python2)
or *tempfile.TemporaryDirectory* (in python3). It means, that every list
has own unique directory, placed likely in */tmp/*.
When list is removed by garbage collector, all items that was stored are lost.

For **FileDeque** stores items in the same way as **FileList**.
Difference between them is that **FileList** implements: *insert*, slicing, indexing.
Because of overlaping indexes of **FileList** while using *insert*, **FileList** stores
own alphabet to index new and inserted items.
**FileDeque** doesn't have indexing so it doesn't take any memory.


Contribute
----------

#. Fork repository on GitHub to start making your changes to the **master** branch (or branch off of it).
#. Write tests that prove that bug or future works as expected
#. Check your code and tests with **tox**
#. Send a pull request!


License
-------

Python-Disk-Collection is under MIT license, see LICENSE for more details.


