Packaging

History

• 2000: distutils
• 2003: PyPI
• 2004: setuptools (easy_install, egg)
• 2007: virtualenv
• 2008: pip
• 2008: distribute (fork from setuptools)
• 2012: distutils2/packaging (*)
• 2013: New era -- PyPA
• PEPs, Standarts, Maintenance, Improvements

Installation tool recomendations

• Use pip to install Python packages from PyPI.
• Use virtualenv to isolate application specific dependencies from a shared Python installation.
• Use pip wheel to create a cache of wheel distributions, for the purpose of speeding up subsequent installations.

pip

$ pip install Package
$ pip install "Package>=1.0,<2.0"
$ pip install -U Package
$ pip install -r requirements.txt
$ pip uninstall Package

$ pip freeze
$ pip list
$ pip list -o  # --outdated

$ pip show Package
$ pip search Package

$ pip completion --bash >> ~/.profile
$ pip completion --zsh >> ~/.zprofile

$ pip install --user Package  # global, no sudo, no venv
$ # ~/.local/bin or $(python -m site --user-base)/bin

$ pip install --download=/home/user/.pip/cache Package
$ pip install --no-index --find-links=file:///home/user/.pip/cache Package

$ pip install wheel
$ pip wheel --wheel-dir=/home/user/.pip/wheels Package
$ pip install --find-links=file:///home/user/.pip/wheels Package

$ # wheels
$ pip wheel Package; pip install Package
$ cat ~/.pip/pip.conf
[global]
find-links = file:///home/user/.pip/wheels
wheel-dir = /home/user/.pip/wheels

$ # cache
$ pip install Package
$ cat ~/.pip/pip.conf
[global]
download-cache = /home/user/.pip/cache
find-links = file://home/user/.pip/cache

pip conf

Requirements

Name

• req.txt
• requirements.pip
• requirements.txt

Actually...

$ tree
.
├── mega_project
│   ├── __init__.py
...
├── README.rst
├── requirements
│   ├── base.txt
│   ├── development.txt
│   ├── production.txt
│   └── testing.txt
├── requirements.txt
├── setup.cfg
└── tests
    ├── __init__.py

Because...

$ tree 
...
├── mega_project
│   ├── __init__.py
│   ├── settings
│   │   ├── __init__.py
│   │   ├── base.py
│   │   ├── development.py
│   │   ├── production.py
│   │   └── testing.py
...

Contents

$ cat requirements.txt
-r requirements/production.txt

$ cat requirements/production.txt
-r base.txt

uWSGI==2.0.6

$ cat requirements/base.txt
# flask
Flask==0.10.1

# flask extensions
Flask-Admin==1.0.8

# deps
Jinja2==2.7.3
MarkupSafe==0.23
WTForms==2.0.1
Werkzeug==0.9.6
itsdangerous==0.24

Rules of Repeatability

• Pin packages to specific versions ("==")
• List all dependencies (~"pip freeze")
• Run "pip install --no-deps -r requirements.txt" (*)

Virtual environments

virtualenv is awesome...

but virtualenvwrapper is more awesome!

Features

• Organizes all of your virtual environments in one place.
• Wrappers for managing your virtual environments .
• Use a single command to switch between environments.
• Tab completion for commands.
• User-configurable hooks for all operations.
• Plugin system for more creating sharable extensions .

link

Interactive shells

ipython is awesome...

but I like bpython!

Features

• In-line syntax highlighting.
• Readline-like autocomplete.
• Expected parameter list for any Python function.
• "Rewind" function.
• Send the code you've entered off to a pastebin.
• Save the code you've entered to a file.
• Auto-indentation.

link

Code style checkers

PEP8

• flake8 (pep8, PyFlakes, "code complexity")
• pylint
• more on PyPI

PEP257 - Docstring Conventions

• Use """triple double quotes""" around docstrings.
• Use r"""raw triple double quotes""" if you use "\" in docstrings.
• Use u"""Unicode triple-quoted strings""" for Unicode docstrings.

• All modules should normally have docstrings.
• All functions and classes exported by a module should have docstrings.
• Public methods (including the __init__ constructor) should have docstrings.
• A package may be documented in the module docstring of the __init__.py file in the package directory.

One-line Docstrings

def is_string(obj):
    """Check if 'obj' is a string."""
    return isinstance(obj, basesring)

• Triple quotes are used even though the string fits on one line.
• The closing quotes are on the same line as the opening quotes.
• There's no blank line either before or after the docstring.
• The docstring is a phrase ending in a period.
• It prescribes the function or method's effect as a command ("Do this", "Return that"), not as a description; e.g. don't write "Returns the pathname ...".

Tools

• pep257
• docformatter
• more on PyPI

Imports

isort

• Future
• Python Standard Library
• Third Party
• Current Python Project
• Explicitly Local (. before import, as in: from . import x)

How do you sort multi line imports?

# grid
from third_party import (lib1, lib2, lib3,
                         lib4, lib5, ...)

# vertical
from third_party import (lib1,
                         lib2,
                         lib3
                         lib4,
                         lib5,
                         ...)

# vertical hanging
from third_party import (
    lib1,
    lib2,
    lib3,
    lib4,
)

# hanging grid
from third_party import (
    lib1, lib2, lib3, lib4,
    lib5, ...)

# own line
from third_party import lib1
from third_party import lib2
from third_party import lib3
...

Project templates

Template

$ tree -a -L 3 cookiecutter-yad/
cookiecutter-yad/
├── cookiecutter.json
├── {{ cookiecutter.repo_name }}
│   ├── {{ cookiecutter.project_name }}
│   │   ├── apps
│   │   ├── {{ cookiecutter.project_name }}
│   │   └── manage.py
│   ├── .gitignore
│   ├── README.rst
│   ├── requirements
│   │   ├── base.txt
│   │   ├── dev.txt
│   │   ├── production.txt
│   │   └── testing.txt
│   └── requirements.txt
├── .gitignore
├── LICENSE
└── README.rst

Cookiecutter

$ cat cookiecutter-yad/cookiecutter.json 
{
	"repo_name": "RepoName",
	"project_name": "project_name",
	"app_name": "app_name",

	"author_name": "Your Name",
	"author_email": "your@email"
}
$ cookiecutter cookiecutter-yad/ 
repo_name (default is "RepoName")? awesome       
project_name (default is "project_name")? awesome
app_name (default is "app_name")? users
author_name (default is "Your Name")? Yan 
author_email (default is "your@email")?

New project

$ tree -a -L 3 awesome/
awesome/
├── awesome
│   ├── apps
│   │   ├── common
│   │   ├── __init__.py
│   │   └── users
│   ├── awesome
│   │   ├── __init__.py
│   │   ├── settings
│   │   ├── urls.py
│   │   └── wsgi.py
│   └── manage.py
├── .gitignore
├── README.rst
├── requirements
│   ├── base.txt
│   ├── dev.txt
│   ├── production.txt
│   └── testing.txt
└── requirements.txt

IDE

One love

Gotta catch 'em all!

PyCharm is awesome!

• Features
• Overview (video)
• PyCharm Web Magic (video)

Misc

ssh_config

$ cat ~/.ssh/config
Host infograph
    User yan
    Port 2222
    HostName infograph.example.com
    IdentityFile ~/.ssh/infograph_rsa

$ # the following lines do the same
$ ssh -i ~/.ssh/infograph_rsa -p 2222 yan@infograph.example.com
$ ssh infograph

Two Scoops of Django

Resources

• Videos: pyvideo.org (en), pyvideo.ru (ru), pep8.ru (ru)
• Digests: pycoders (en), pythonweekly (en), pythondigest (ru)
• Blogs: asvetlov (ru), pep8.ru/blog (ru)