DEWI core: A plugin and typesafe config tree framework

Name

DEWI: Old Welsh form of David

The name is chosen because of the similarity to DWA, which was the project's original name, which stands for Developer's Work Area.

Purpose

This code is the minimal core part of DEWI.

The plugins ensure load codes dynamically, without loading everything. An application implementation is also added in MainApplication class.

The other functionality is the config tree, which is a tree of MutableMapping nodes with further improvements. The class is called as Node. A generic helper class is also added called as config.

Installation

It can be installed from source:

python3 setup.py

Or from pip:

pip install dewi_core

Usage as a plugin framework

A minimal example can be found in the samples/as_framework directory, the application is named as Steven.

Assuming that it's already created, it can be the aforementioned way:

dewi -p example.my.custom.Plugin mycustom-command
dewi -p steven.StevenPlugin xssh ....

The exact plugin can be hidden if there is a main entry point or script:

#!/usr/bin/env python3
import sys

from dewi_core.application import Application


def main():
    app = Application('steven')
    app.add_plugin('steven.StevenPlugin')
    app.run(sys.argv[1:])


if __name__ == '__main__':
    main()

Usage as a regular Python library

Some parts of DEWI can be used as regular Python library, without the Plugin boilerplate. A simple example is creating a somewhat typesafe (config) tree:

from dewi_core.config.config import Config
from dewi_core.config.node import Node


class Hardware(Node):
    def __init__(self):
        self.hw_type: str = ''
        self.mem_size: int = None
        self.mem_free: int = None
        self.mem_mapped: int = None


class MainNode(Node):
    def __init__(self):
        # Handling as str, but None is used as unset
        self.version: str = None
        self.hw = Hardware()
        # ... further fields

    def __repr__(self) -> str:
        return str(self.__dict__)


class SampleConfig(Config):
    def __init__(self):
        super().__init__()
        self.set('root', MainNode())

    def get_main_node(self) -> MainNode:
        return self.get('root')


# ....
sc = SampleConfig()
sc.get_main_node().hw.mem_size = 1024  # OK
sc.set('root.hw.mem_size', 1024)       # OK
sc.set('root.hw.memsize', 1024)        # NOT OK, typo

# but...
c = Config()
c.set('root.hw.mem_size', 1024)  # OK
c.set('root.hw.memsize', 1024)   # OK, but typo

As you can see, DEWI can be used as library, and it can contain slightly different solutions of the same problem.