Expert Python Programming - Third Edition

The possible uses

While annotations have great potential, they are not widely used. An article explaining the new features that were added to Python 3 (refer to https://docs.python.org/3/whatsnew/3.0.html) says that the intent of this feature as follows:

"The intent is to encourage experimentation through metaclasses, decorators, or frameworks."

On the other hand, PEP 3107, which officially proposed function annotations, lists the following set of possible use cases:

• Providing typing information:
  • Type checking
  • Let IDEs show what types a function expects and returns
  • Function overloading/generic functions
  • Foreign language bridges
  • Adaptation
  • Predicate logic functions
  • Database query mapping
  • RPC parameter marshaling

• Other information: ...