02: Python Packages for Pyramid Applications¶
Most modern Python development is done using Python packages, an approach Pyramid puts to good use. In this step we redo "Hello World" as a minimal Python package inside a minimal Python project.
Python developers can organize a collection of modules and files into a
namespaced unit called a package. If a directory
sys.path and has a special file named
__init__.py, it is treated
as a Python package.
Packages can be bundled up, made available for installation, and installed
through a toolchain oriented around a
setup.py file. For this tutorial,
this is all you need to know:
We will have a directory for each tutorial step as a project.
This project will contain a
setup.pywhich injects the features of the project machinery into the directory.
In this project we will make a
tutorialsubdirectory into a Python package using an
__init__.pyPython module file.
We will run
pip install -e .to install our project in development mode.
You'll do your development in a Python package.
That package will be part of a project.
Make a Python "package" directory with an
Get a minimum Python "project" in place by making a
tutorialproject in development mode.
Make an area for this tutorial step:
cd ..; mkdir package; cd package
package/setup.py, enter the following:
from setuptools import setup # List of dependencies installed via `pip install -e .` # by virtue of the Setuptools `install_requires` value below. requires = [ 'pyramid', 'waitress', ] setup( name='tutorial', install_requires=requires, )
Make the new project installed for development then make a directory for the actual code:
$VENV/bin/pip install -e . mkdir tutorial
Enter the following into
Enter the following into
from waitress import serve from pyramid.config import Configurator from pyramid.response import Response def hello_world(request): print('Incoming request') return Response('<body><h1>Hello World!</h1></body>') if __name__ == '__main__': with Configurator() as config: config.add_route('hello', '/') config.add_view(hello_world, route_name='hello') app = config.make_wsgi_app() serve(app, host='0.0.0.0', port=6543)
Run the WSGI application with:
Open http://localhost:6543/ in your browser.
Python packages give us an organized unit of project development. Python
setup.py, give us special features when our package is
installed (in this case, in local development mode, also called local editable
mode as indicated by
In this step we have a Python package called
tutorial. We use the same name
in each step of the tutorial, to avoid unnecessary retyping.
tutorial directory we have the files that handle the packaging
of this project. At the moment, all we need is a bare-bones
Everything else is the same about our application. We simply made a Python
package with a
setup.py and installed it in development mode.
Note that the way we're running the app (
python tutorial/app.py) is a bit
of an odd duck. We would never do this unless we were writing a tutorial that
tries to capture how this stuff works one step at a time. It's generally a bad
idea to run a Python module inside a package directly as a script.