pygopher-interfaces¶
Go-style interfaces for Python
Interfaces in the Go programming language are a bit different than those found in Java or C++, as they are implicit. This means that there is no explicit “implements” relationship between the interface definition and an implementation of the defined interface. A type implements an interface by implementing all of the methods defined. When we wish to define an interface in Python, we typically use abstract base classes to define them because we can enforce implementation of methods. This requires us to use inheritance, which couples the interface and the implementation.
This package emulates Go-style interfaces by creating an Interface
metaclass that can be used to construct Python
classes that override issubclass
to test whether a class implements the methods of the interface class, rather than
whether it inherits from the interface class.
This is a tiny package that emulates on of my favorite features of Go.
Installation¶
pip install pygopher-interfaces
# or:
# pipenv install pygopher-interfaces
# poetry add pygopher-interfaces
Usage¶
To create an interface class, use the Interface
metaclass.
from pygopher.interfaces import Interface
class RepositoryInterface(metaclass=Interface):
def get(account_id: int) -> Account:
raise NotImplementedError
def add(account: Account):
raise NotImplementedError
class MysqlRepository:
def get(account_id: int) -> Account:
...
def add(account: Account):
...
>>> issubclass(MysqlRepository, RepositoryInterface)
True