``cli`` : command line interpreter
===================================

As Catherine Devlin, the author of `cmd2 <https://pythonhosted.org/cmd2/>`_ explained it:

| Slightly after the bronze age came the command line interpreter.
| I'm talking about **command line interpreters**
| that is somewhat more specific terms than **command line applications**
| or **command line utilities**

A command line interpreter is a program that is

- plain text
- gives you a prompt
- it gets all of its input at once
- produces his output usually as text lines
- gives you a prompt again

unix shell instructions are a good example of that.
A command line utilities is a unix-like program that gets all of its inputs at once
and gives a result at once.

At the other side, a text user interface is a litlle bit like a gui, it's closer to a gui.
at this time, you have to think of how much effort your interface is worth,

| otherwise it's gonna kill you to write it (Catherine Devlin)

Basic cli functionnalities
---------------------------

A complete command line interpreter written with ``cmd``

- it recognizes the concept of help (contextual help)
- the previous commands (history) can be called again with the keyboard's up and down arrows
- if yout hit Ctr-R and the first letters of a command you can call it again
  (bash-style history)
- the tab key will finish out your command

how to use it
--------------

::

    >>> from cli import Cli
    >>> prompt = Cli()
    >>> prompt.cmdloop()
    cli (command line interpreter)
    (type help or ? for commands list)
    #Prompt> ?

    Documented commands (type help <command>):
    ==========================================
    EOF  exit

    Undocumented commands:
    ======================
    cmd  help  quit

    #Prompt>

to add a command, just use inheritance::


    >>> from cli import Cli
    >>> class Prompt(Cli):
    ...   def do_hello(self, line):
    ...      print "hello %s", line
    ...
    >>> prompt = Prompt()
    >>> prompt.cmdloop()
    cli (command line interpreter)
    (type help or ? for commands list)
    #Prompt> ?

    Documented commands (type help <command>):
    ==========================================
    EOF  exit

    Undocumented commands:
    ======================
    cmd  hello  help  quit

    #Prompt> hello world


.. glossary::

    CLI
        CLI stands for Command Line Interface, is a tool that, well, it gives you a prompt

.. literalinclude:: ../snippets/cli.py
    :caption: basic command line utility library

If you want your :term:`cli` to have more functionalities, try `cm2 <http://www.phyast.pitt.edu/~micheles/python/cmd2.html>`_.

.. important:: Don't use `input()` but `raw_input()` for your command lines