PYTHONRC

Initialization script for the interactive Python interpreter. Its main purpose is to enhance the overall user experience when working in such an environment by applying some improvements to the standard console.

It also works with IPython and BPython, although its utility in that kind of scenarios can be argued.

Tested in GNU/Linux with Python versions 2.7 and 3.4.

Please read the Installation section below.

Features

• User input completion

  • Introduces a completion mechanism for inputted commands in Python 2.
  • In Python 3, where the standard console is a lot nicer, it just impersonates the default completion machinery to keep the consistency with the behavior in Python 2 (and so it's still possible to adapt it to the user's needs).

• Command History

  • Creates a callable, singleton object called history, placing it into the __builtins__ object to make it easily available, which enables the handling of the command history (saving some input lines to a file of your choice, listing the commands introduced so far, etc.). Try simply history() on the Python prompt to see it in action; inspect its members (with dir(history) or help(history.write)) for more information.

• Color prompt

  • Puts a colorful prompt in place, if the terminal supports it.

• Implementation of a bash's "operate-and-get-next" clone

  • Enables a quick re-edition of a code block from the history by successive keypresses of the Ctrl-o hotkey.

Installation

• You must define in your environment (in GNU/Linux and MacOS X that usually means your ~/.bashrc file) the variable 'PYTHONSTARTUP' containing the path to pythonrc.py.

• It is also highly recommended to define the variable 'PYTHON_HISTORY_FILE'. Remember that BPython (unlike the standard interpreter or IPython) ignores that variable, so you'll have to configure it as well by other means to be able to use the same history file there (for instance, in Linux, the file ~/.config/bpython/config is a good place to start, but please read BPython's documentation).

Example configurations

• Extract of ~/.bashrc

# python
export PYTHONSTARTUP=~/.python/pythonrc.py
export PYTHON_HISTORY_FILE=~/.python/.python_history

## You may want to also uncomment some of this lines if using and old
## version of virtualenvwrapper
# export VIRTUALENVWRAPPER_PYTHON=/usr/bin/python3.4
# export WORKON_HOME=~/.python/virtualenvs
# source $(which virtualenvwrapper.sh)

• Extract of ~/.config/bpython/config

[general]
color_scheme = default
hist_file = ~/.python/.python_history
hist_lenght = 1000

Bugs / Caveats / Future enhancements

• No module/package introspection for the last argument in commands of the form from <package> import <not_completing_this> (this, in fact, could be a not so bad thing, because it doesn't execute side effects, e.g. modules' init code).

• Depending on the user's system, the compilation of the packages' and modules' list for completing import ... and from ... import ... commands can take a long time, especially the first time it is invoked.

• When completing things like a method's name, the default is to also include the closing parenthesis along with the opening one, but the cursor is placed after it no matter what, instead of between them. This is because of the python module readline's limitations. You can turn off the inclusion of the closing parenthesis; if you do so, you might be also interested in modifying the variable called dict_keywords_postfix (especially the strings that act as that dictionary's indexes).

• IPython has its own %history magic. I did my best to not interfere with it, but I don't know the actual consequences. Also, it's debatable if it even makes sense to use this file with IPython and/or BPython (though having a unified history for all the environments is really nice). You could define some bash aliases like

alias ipython='PYTHONSTARTUP="" ipython'
alias bpython='PYTHONSTARTUP="" bpython'

to be on the safer side.

• Could have used the module six for better clarity. Right now it uses my own made up stubs to work on both Python 2 and 3.

• Needs better comments and documentation, especially the part on history handling.

• Probably a lot more. Feel free to file bug reports ;-)