Python Shelve Module Extension

The Python standard library shelve module can create persistent (saved on binary files) Python dictionaries, similar to databases, where the key is a string and the value is any object that can be serialized (Pickle).

This extension, as shown in the video below, provides a unique storage directory that can be assigned with an environmental variable. For example, a database can be created inside a Jupyter notebook and then easily shared with a python REPL.

Installation

Define the environmental variable where the databases should be stored.

On Windows OS:

   set MYSHELF=C:\Users\users\MyShelf

On Linux OS:

   export MYSHELF=/home/user/MyShelf

When the variable MYSHELF is not defined the directory HOME\Documents\My Shelf will be used.

Install the module with pip.

On Windows OS:

   py -m pip install git+https://sevepy@bitbucket.org/sevepy/myshelf.git#egg=myshelf   

On Linux OS:

   pip install git+https://sevepy@bitbucket.org/sevepy/myshelf.git#egg=myshelf   

New Methods

This notebook shows an example on how to use this extension. To open a new database in the specified directory the module has a new function named open_default with the same shelve.open API.

The inspect method, associated with a new database instance, prints a table with the key, type of object stored and a one-line representation of the value.