impler 0.1.0

Implementation pattern*

/* inspired by Rust

Useful when it is needed to extend a class (usually 3d party) with some methods or interfaces

Install

pip install impler

or

poetry add impler

Usage

Methods implementation

Using implementation pattern you can extend any class (even 3rd party) with regular, class or static methods.

from impler import impl
from pydantic import BaseModel


@impl(BaseModel)
def fields_count(self: BaseModel):
    return len(self.__fields__)


class Point(BaseModel):
    x: int = 0
    y: int = 1


point = Point()
print(point.fields_count())

Class methods

@impl_classmethod(BaseModel)
def fields_count(cls):
    return len(cls.__fields__)


# or

@impl(BaseModel)
@classmethod
def fields_count(cls):
    return len(cls.__fields__)

Static methods

@impl_staticmethod(BaseModel)
def zero(cls):
    return 0


# or

@impl(BaseModel)
@staticmethod
def zero(cls):
    return 0

Async methods

@impl(BaseModel)
async def zero(cls):
    await asyncio.sleep(1)
    return 0

Interfaces implementation

The same way you can extend any class with the whole interface

Here is example of the base interface, which

from pathlib import Path


class BaseFileInterfase:
    def dump(self, path: Path):
        ...

    @classmethod
    def parse(cls, path: Path):
        ...

This is how you can implement this interface for Pydantic BaseModel class:

from impler import impl
from pydantic import BaseModel
from pathlib import Path


@impl(BaseModel, as_parent=True)
class ModelFileInterface(BaseFileInterface):
    def dump(self, path: Path):
        path.write_text(self.json())
        
    @classmethod
    def parse(cls, path: Path):
        return cls.parse_file(path)

If as_parent parameter is True the implementation will be injected to the list of the target class parents.

Then you can check if the class or object implements the interface:

print(issubclass(BaseModel, BaseFileInterfase))
# True

print(issubclass(Point, BaseFileInterfase))
# True

print(isinstance(point, BaseFileInterface))
# True

The whole api documentation could be found by the link