Metadata-Version: 2.0
Name: baron
Version: 0.2
Summary: Full Syntax Tree for python to make writing refactoring code a realist task
Home-page: https://github.com/Psycojoker/baron
Author: Laurent Peuch
Author-email: cortex@worlddomination.be
License: lgplv3+
Keywords: ast fst refactoring syntax tree
Platform: UNKNOWN
Classifier: Development Status :: 3 - Alpha
Classifier: Intended Audience :: Developers
Classifier: Programming Language :: Python :: 2
Classifier: Programming Language :: Python :: 2.7
Classifier: Programming Language :: Python :: 2 :: Only
Classifier: License :: OSI Approved :: GNU Lesser General Public License v3 (LGPLv3)
Classifier: Topic :: Software Development
Classifier: Topic :: Software Development :: Code Generators
Classifier: Topic :: Software Development :: Libraries
Requires-Dist: rply

Introduction
============

Baron is a Full Syntax Tree (FST) library for Python. By opposition to
an `AST <https://en.wikipedia.org/wiki/Abstract_syntax_tree>`_ which
drops some syntax information in the process of its creation (like empty
lines, comments, formatting), a FST keeps everything and guarantees the
operation fst\_to\_code(code\_to\_fst(source\_code)) == source\_code.

Installation
============

::

    pip install baron

Basic Usage
===========

::

    from baron import parse, dumps

    fst = parse(source_code_string)
    source_code_string == dumps(fst)

There is a good chance that you'll want to use
`RedBaron <https://github.com/Psycojoker/redbaron>`_ instead of using
Baron directly. Think of Baron as the "bytecode of python source code"
and RedBaron as some sort of usable layer on top of it.

If you don't know what Baron is or don't understand yet why it might be
useful for you, read the `« Why is this important? »
section <#why-is-this-important>`_.

Documentation
=============

Baron documentation is available on `Read The
Docs <http://baron.readthedocs.org/en/latest/>`_.

Why is this important?
======================

The usage of a FST might not be obvious at first sight so let's consider
a series of problems to illustrate it. Let's say that you want to write
a program that will:

-  rename a variable in a source file... without clashing with things
   that are not a variable (example: stuff inside a string)
-  inline a function/method
-  extract a function/method from a series of line of code
-  split a class into several classes
-  split a file into several modules
-  convert your whole code base from one ORM to another
-  do custom refactoring operation not implemented by IDE/rope
-  implement the class browser of smalltalk for python (the whole one
   where you can edit the code of the methods, not just showing code)

It is very likely that you will end up with the awkward feeling of
writing clumpsy weak code that is very likely to break because you
didn't thought about all the annoying special cases and the formatting
keeps bothering you. You may end up playing with
`ast.py <http://docs.python.org/2/library/ast.html>`_ until you realize
that it removes too much information to be suitable for those
situations. You will probably ditch this task as simple too complicated
and really not worth the effort. You are missing a good abstraction that
will take care of all of the code structure and formatting for you so
you can concentrate on your task.

The FST tries to be this abstraction. With it you can now work on a tree
which represents your code with its formatting. Moreover, since it is
the exact representation of your code, modifying it and converting it
back to a string will give you back your code only modified where you
have modified the tree.

Said in another way, what I'm trying to achieve with Baron is a paradigm
change in which writing code that will modify code is now a realist task
that is worth the price (I'm not saying a simple task, but a realistic
one: it's still a complex task).

Other
-----

Having a FST (or at least a good abstraction build on it) also makes it
easier to do code generation and code analysis while those two
operations are already quite feasible (using
`ast.py <http://docs.python.org/2/library/ast.html>`_ and a templating
engine for example).

Some technical details
======================

Baron produces a FST in the form of JSON (and by JSON I mean Python
lists and dicts that can be dumped into JSON) for maximum
interoperability.

Baron FST is quite similar to Python AST with some modifications to be
more intuitive to humans, since Python AST has been made for CPython
interpreter.

Since playing directly with JSON is a bit raw I'm going to build an
abstraction on top of it that will looks like BeautifulSoup/jQuery.

State of the project
====================

Currently, Baron has been tested on the top 100 projects and the FST
converts back exactly into the original source code. So, it can be
considered quite stable, but it is far away from having been battle
tested.

Since the project is very young and no one is already using it except my
project, I'm open to changes of the FST nodes but I will quickly become
conservative once it gets some adoption and will probably accept to
modify it only once or twice in the future with clear indications on how
to migrate.

**Baron is targeting python 2.[67]**. It has not been tested on python3
but should be working for most parts (except the new grammar like yield
from, obviously).

Tests
=====

Run either ``py.test tests/`` or ``nosetests`` in the baron directory.

Community
=========

You can reach us on
`irc.freenode.net#baron <https://webchat.freenode.net/?channels=%23baron>`_.

Misc
====

`Old blog post announcing the
project. <http://worlddomination.be/blog/2013/the-baron-project-part-1-what-and-why.html>`_
Not that much up to date.


