Eases the transition from PIL to Pillow for projects.
Pillow is a new replacement for PIL that works as a drop-in replacement. It’s great, but unfortunately, users must first uninstall PIL before installing Pillow, as they share a namespace.
This makes it very hard for public projects to easily depend on either PIL or Pillow without inevitably breaking something (perhaps in subtle ways).
Basically, without having full control of every system the package is running on, it’s easy to break something, and hard to transition.
This package aims to “solve” that by providing a single dependency that can intelligently depend on either PIL or Pillow, based on what’s already on the system. Packages that still need to work if PIL is installed, but aim to transition to Pillow, can simply depend on the pillowfight package.
How it works
This package is provided as a source distribution with a simple setup script. When pillowfight is installed for the first time, its setup script will run and start inspecting the system.
The setup script will look to see if PIL is already installed. If so, it will print a warning saying that PIL is deprecated and to install Pillow. It will then turn around and depend on PIL.
If PIL is not installed, it will instead depend on Pillow.
Why we wrote this
We use Django and Pillow for a product that sysadmins can install in their network. There are a lot of configurations out there, and a lot of older systems already using PIL,
We’ve been trying to figure out the right strategy for getting new and existing users onto Pillow without breaking existing installs. We don’t have much control over the system, so we knew we had to be clever.
A lot of projects out there seem to have modify their setup.py scripts to check what’s on the system, but in practice, that doesn’t work too well. When building packages, the requires.txt files would be populated with either PIL or Pillow, and that just wasn’t going to work.
So we wrote this as a way to have a stable dependency that could do the right thing. We hope others will find it useful.