A scripting tool

pip install yaz==1.1.2


YAZ (Yet another z)

It's purpose is to easily expose python functions and classes, represented as tasks and plugins, on your console command line.

Yaz is inspired by z, a scripting tool used by Zicht Online.

Features include:

  • expose python functions using @yaz.task
  • expose type aware function parameters (string, integer, float, boolean, file, etc)
  • group tasks together by extending yaz.Plugin (nested classes provide further grouping)
  • handling dependencies between plugins using @yaz.dependency
  • asyncio aware


pip3 install --upgrade yaz

Expose a single function (task)

The simplest usage of yaz is to expose a python function to be executed from the shell. For example, when you want to run the file hello_world.py from shell, you could use the following python code:

#!/usr/bin/env python3
# file: examples/01_say.py

import yaz

def say(message="Hello World!"):
    return message

if __name__ == "__main__":

The above can be called using ./examples/01_say.py --help, resulting in a list of options. The message parameter is optional, just like it is in the python code. For example:

usage: say.py [-h] [--message MESSAGE]

optional arguments:
  -h, --help         show this help message and exit
  --message MESSAGE  defaults to message='Hello World!'

When multiple functions are decorated with @yaz.task, all these functions will be exposed to the console. This means that the desired function will need to be specified when the script is run.

Expose functions in a class (plugin with tasks)

It is common to group functions, with the same subject, together in a class. Such a class must extend the yaz.Plugin class to allow, amongst other things, for class initialization when the task is executed.

Furthermore, classes can have dependencies on each other which will be resolved by yaz. This is shown in the example below with @yaz.dependency.

#!/usr/bin/env python3
# file: examples/02_food.py

import yaz

class Helper(yaz.Plugin):
    def output(self, message, shout):
        if shout:

class Food(yaz.Plugin):
    def set_helper(self, helper: Helper):
        self.helper = helper

    def breakfast(self, message="Breakfast is ready", shout: bool = False):
        """Say something in the morning"""
        self.helper.output(message, shout)

    def lunch(self, message="Time for lunch", shout: bool = False):
        """Say something in the afternoon"""
        self.helper.output(message, shout)

    def dinner(self, message="Dinner is served", shout: bool = False):
        """Say something in the evening"""
        self.helper.output(message, shout)

if __name__ == "__main__":

The above can be called using ./examples/02_food.py lunch --shout, resulting in DINNER IS SERVED. This is achieved using the following steps:

  1. When yaz.main() is called, all the plugins and tasks are collected, and it is determined that the def lunch(...) function is to be called.
  2. The Food class is initiated.
  3. The dependencies for the Food class are resolved, i.e. the Helper class is initiated and def set_helper is called.
  4. The lunch method is called and yaz.main() prints its return value.


  • todo: explain multiple plugins
  • todo: explain different argument types
  • todo: explain @yaz.task(OPTIONS)
  • todo: explain plugin inheritance
  • todo: explain coroutines / asyncio
  • todo: explain available base plugins: yaz_templating_plugin and yaz_scripting_plugin