pundle 0.1.2

Requirements management tool.

Modern python package management for python development

For development we need two things - right python interpreter and right packages versions.

We can get interpreter by system package manager - brew, apt, yum etc. You can even install some packages with system manager, but quickly you get to the point where repositories are not contain appropriate package version. And now you are often in situation when system has not actual interpreter version.

And even worse is situation when you develop several projects and every project need different interpreter and indeed every project need its own versions of packages.

Packages situation were solved with virtualenv. Its not best solution but it works.

Interpreter situation is solved now with [pyenv](https://github.com/yyuu/pyenv) project. You can install as many interpreters as you need and all of them are separated and does not augument system behaviour:

> brew install pyenv > pyenv install 3.4.1 … installing > pyenv shell 3.4.1 > python –version Python 3.4.1

This interpreter is completely independent from your system, and you activate it in your shell and it will switch python version for your according to projects .pyenv-version file.

So, its cool, I like how pyenv works. But we all know that pyenv works similar to how rbenv works for ruby.

If we grab rbenv from ruby, why no to grab Bundler project? How it like, you have a Gemfile, with packages description. Then you call bundler install and if you have not Gemfile.lock it will install latest packages versions that play nice with your Gemfile or if you have Gemfile.lock it will install packages according it.

And when you start you rails application with bundle exec rails s bundler looking into projects Gemfile.lock and loads appropriate packages versions.

If you switch branch and your Gemfile.lock changes, packages will be switched too, and this is not magic - we just load versions according to file.

And in my opinion this is a right thing, and something that we need in python. I dont like to rebuild virtualenvs, I dont understand why I need them anyway. Why I need to install Django number of my projects times.

So I created Pundle.

Pundle

Main goal of pundle is activating right packages versions on interpreter start. Two ways - do it magically in usercustomize.py that is in your home directory per python interpreter version. Or you can put logic for activating versions to your manage.py or other entry points of your project.

I have not find any way to augument python behaviour over environment variables, so we need some work before we can use pundle - I dont have ideas how to have something like bundler runner now.

Personaly I like usercustomize.py approach:

# activate python, if still have not .pyenv-version > pyenv shell 3.4.1 > git clone https://github.com/Deepwalker/pundler ~/.pundle > python ~/.pundle/pundle.py fixate

Fixate command will create usercusomize.py for current python interpreter. You will need fixate pundle for every python version you want to use.

Anyway, we are ready to install packages from your requirements.txt:

> python -m pundle install … long work here

And you will get frozen.txt file with frozen packages versions and some information:

alembic==0.7.4 # alembic << requirements file arrow==0.5.0 # arrow << requirements file awesome-slugify==1.6 # awesome-slugify << requirements file babel==1.3 # Babel>=1.0 << Flask-Babel << requirements file dawg-python==0.7.1 # dawg-python>=0.7 << pymorphy2 << requirements file docopt==0.6.2 # docopt>=0.6 << pymorphy2 << requirements file

Now your packages are install to the ~/.pundlerdir/CPython-3.4.1 directory. And you can use it with your fixated python:

> python … bla bla bla 3.4.1 >>> import arrow >>> arrow.__version__ ‘0.5.0’

Pundle get frozen version from frozen.txt, and activate package from ~/.pundledir/CPython-3.4.1-default/arrow-0.5.0/

>>> arrow.__file__
'/Users/mighty_user/.pundledir/CPython-3.4.1-default/arrow-0.5.0/arrow/__init__.py'

All packages are activating on python startup.

Going deeper

We have additional commands for working with packages. upgrade, entry_points, exec and edit.

If you frozen versions of package is old and you want to update it, you need upgrade command:

> python -m pundle upgrade django

Or you can update all packages:

> python -m pundle upgrade

entry_points will show you all commands that your packages offer you:

> python -m pundle entry_points nomad (nomad 1.9) gunicorn_paster (gunicorn 19.2.0) gunicorn_django (gunicorn 19.2.0) mako-render (Mako 1.0.1) webassets (webassets 0.10.1) alembic (alembic 0.7.4) pyflakes (pyflakes 0.8.1) pyscss (pyScss 1.3.4) pybabel (Babel 1.3) gunicorn (gunicorn 19.2.0)

And of course we have command to start this command:

> python -m pundle exec pyflakes start.py start.py:2: ‘url_for’ imported but unused

Last command is edit - it will help you find fast where the package code is:

> python -m pundle edit arrow /Users/main_universe_user/.pundledir/CPython-3.4.1-default/arrow-0.5.0

Use it, feel it, like it, share it. Commit, pull request.