Protocols in Python

The aim of this page📝is to conceptualize protocols in python

1. define

• protocol is a set of operations that a type must support to implement
• they do not need to be defined as separate interfaces or base classes
• that would be the case in nominally typed languages such as C# or Java
• it is enough to provide functioning implementations of these operations
• protocol support demands specific behavior

2. container protocol requirements

• requirement: membership testing using in and not in

3. sized protocol requirements

• requirement: length of a type by checking with len(container)

4. iterable protocol requirements

• yield items one by one as they are requested
• iterable is an object from which you can fetch a sequence of other objects
• the act of fetching from an iterable is known as iteration
• they can be used in for loops

5. sequence protocol requirements

• items can be retrieved using []
• items can be searched-for with sequence.idex(item)
• items can be counted with sequence.count()
• reversed copy can be produced with reversed(sequence)
• must support iterable + sized + container