# The Deprecation Process

PyPDF2 strives to be an excellent library for its current users and for new ones. We are careful with introducing potentially breaking changes, but we will do them if they provide value for the community on the long run.

We hope and think that deprecations will not happen soon again. If they do, users can rely on the following procedure.

## Semantic Versioning

PyPDF2 uses semantic versioning. If you want to avoid breaking changes, please use dependency pinning (also known as version pinning). In Python, this is done by specifying the exact version you want to use in a requirements.txt file. A tool that can support you is pip-compile from pip-tools.

If you are using Poetry it is done with the poetry.lock file.

## How PyPDF2 deprecates features

Assume the current version of PyPDF2 is x.y.z. After a discussion (e.g. via Github issues) we decided to remove a class / function / method. This is how we do it:

1. x.y.(z+1): Add a PendingDeprecationWarning. If there is a replacement, the replacement is also introduced and the warning informs about the change and when it will happen. The docs let users know about the deprecation and when it will happen and the new function. The CHANGELOG informs about it.

2. (x+1).0.0: The PendingDeprecationWarning is changed to a DeprecationWarning. The CHANGELOG informs about it.

3. (x+2).0.0: The code and the DeprecationWarnings are removed. The CHANGELOG informs about it.

This means the users have 3 warnings in the CHANGELOG, a PendingDeprecationWarning until the next major release and a DeprecationWarning until the major release after that.

Please note that adding warnings can be a breaking change for some users; most likely just in the CI. This means it needs to be properly documented.