Reusable apps

By Alex Gaynor

Note: Alex talked FAST but it was one of the best talks at DjangoCon.


  • similiar patterns
  • write once, use everywhere
  • no need to reinvent this wheel

But Standard apps patterns are not truly reusable

Too many differences in business logic between systems

  • ex comments:
  • comments apps have to cover many different business cases
  • differing storage (comments in a group, against a logic)

What about class based views?

  • Better than function based views because you have inheritance
  • django.contrib.admin has good examples of class based views

Reusable frameworks

  • an example would be badges
  • brabeion
  • You can’t predict all the ways people want to use your software
  • You know the common ways (80/20)
  • Provide default behavior and let people swap it out
  • django-taggit is his example

    • non-integer primary keys
    • per-user tags
    • official tags
    • custom caching managers, or anything else

Custom Backends

Many different backend systems

  • django-registration
  • django.core.cache
  • django.contrib.auth
  • django.core.files
  • django.contrib.sessions

Libraries approach

  • not everything is business logic
  • Good API design
  • Well defined problem spaces