fades 2.0

fades
=====

fades, a FAst DEpendencies for Scripts, is a system that automatically
handles the virtualenvs in the simple cases normally found when
writing scripts or simple programs.


What does it do?
----------------

*fades* will automagically create a new virtualenv (or reuse a previous
created one), installing the necessary dependencies, and execute
your script inside that virtualenv, with the only requirement
of executing the script with *fades* and also marking the required
dependencies.


How to use it?
==============

When you write an script, you have to take two special measures:

- need to execute it with *fades* (not *python*)

- need to mark those dependencies

At the moment you execute the script, fades will search a
virtualenv with the marked dependencies, if it doesn't exists
fades will create it, and execute the script in that environment.


How to execute the script with fades?
-------------------------------------

You can always call your script directly with fades::

fades myscript.py

However, for you to not forget about fades and to not execute it
directly with python, it's better if you put at the beggining of
the script the indication for the operating system that it should
be executed with fades... ::

#!/usr/bin/fades

...and also set the executable bit in the script::

chmod +x yourscript.py


How to mark the dependencies to be installed?
---------------------------------------------

The procedure to mark a module imported by the script as a *dependency
to be installed by fades* is by using a comment.

This comment will normally be in the same line of the import (recommended,
less confusing and less error prone in the future), but it also can be in
the previous one.

The simplest comment is like::

import somemodule # fades.pypi
from somepackage import othermodule # fades.pypi

The ``fades.pypi`` is mandatory, it may allow more options in the future.

With that comment, *fades* will install automatically in the virtualenv the
``somemodule`` or ``somepackage`` from PyPI.

Also, you can indicate a particular version condition, examples::

import somemodule # fades.pypi == 3
import somemodule # fades.pypi >= 2.1
import somemodule # fades.pypi >=2.1,<2.8,!=2.6.5

Sometimes, the project itself doesn't match the name of the module; in
these cases you can specify the project name (optionally, before the
version)::

import bs4 # fades.pypi beautifulsoup4
import bs4 # fades.pypi beautifulsoup4 == 4.2


How to control the virtualenv creation and usage?
-------------------------------------------------

You can influence several details of all the virtualenv related process.

*Note: the functionality in this parragraph is still not ready*.
The most important detail is which version of Python will be used in
the virtualenv. Of course, the corresponding version of Python needs to
be installed in your system, but you can control exactly which one to use.

*Note: the functionality in this parragraph is still not ready*.
No matter which way you're executing the script (see above), you can
pass a ``-p`` or ``--python`` argument, indicating the Python version to
be used just with the number (``2.7``), the whole name (``python2.7``) or
the whole path (``/usr/bin/python2.7``).

Other detail is the verbosity of *fades* when telling what is doing. By
default, *fades* only will use stderr to tell if a virtualenv is being
created, and to let the user know that is doing an operation that
requires an active network connection (e.g. installing a new dependency).

If you call *fades* with ``-v`` or ``--verbose``, it will send all internal
debugging lines to stderr, which may be very useful if any problem arises.
On the other hand if you pass the ``-q`` or ``--quiet`` parameter, *fades*
will not show anything (unless it has a real problem), so the original
script stderr is not polluted at all.


How to install it
=================

Several instructions to install fades in different systems.


Dependencies
------------

Fades depends on ``python-xdg`` package. This package should be installed on
any GNU/Linux OS wiht a freedesktop.org GUI. However it is an
**optional** dependency.

You can install it in Ubuntu/Debian with::

apt-get install python-xdg

And on Archlinux with::

pacman -S python-xdg

It also depends on the ``pkg_resources`` package, that comes in with
``setuptools``. Note I didn't find any system where that is not
already included (it's even there in a clean virtualenv).


For debian/ubuntu
-----------------

You have a .deb `here <http://taniquetil.com.ar/fades/fades-latest.deb>`_.
Download it and install doing::

sudo dpkg -i fades-latest.deb


For Archlinux
-------------

We have an AUR package `here <https://aur.archlinux.org/packages/fades>`_.
If you are a yaourt user you can install fades with a simple::

yaourt -S fades


Using pip if you want
----------------------
::

pip3 install fades


Multiplatform tarball
---------------------

Finally you can always get the multiplatform tarball and install
it in the old fashion way::

wget http://taniquetil.com.ar/fades/fades-latest.tar.gz
tar -xf fades-latest.tar.gz
cd fades-*
sudo ./setup.py install


Can I try it without installing it?
-----------------------------------

Yes! Branch the project and use the executable::

git clone https://github.com/PyAr/fades.git
cd fades
bin/fades your_script.py


Get some help, give some feedback
=================================

You can ask any question or send any recommendation or request to
the `mailing list <http://listas.python.org.ar/mailman/listinfo/fades>`_.

Also, you can open an issue
`here <https://github.com/PyAr/fades/issues/new>`_ (please do if you
find any problem!).

Thanks in advance for your time.