safetydance

safetydance is a Python framework for defining type-safe and flexibly composable application steps with a shared execution context for sharing variables between the steps. The design of safetydance is partially inspired by <https://cucumber.io>_.

Description

safetydance defines a set of decorators that rewrite functions as steps and scripts.

A step should be a function with a name that reads easily, like a short phrase or sentence. Steps may take arguments and they may access variables defined for the "context scope". Steps may call other steps, too.

A script is a function composing the execution of a series of steps. A script is a step that defines an execution context. Scripts may also call other scripts. The primary difference between a script and a step is the implicit definition of the execution context. TODO When a script calls another script the current execution context may be passed as a kwarg to the nested script; by default all scripts execute in their own execution context; that is, if a step is used by both an originating and a nested script the context variables it accesses are determined by the calling script's execution context.

Context Scope Variables

A context scope variable is sort of like a global variable. The run of a script defines a context where context_data variables are stored for access by steps.

Think of a conversation between two friends. Much of the conversation will reference assumed shared knowledge, or context. For safetydance, the context scope provides a way for steps to share assumed context to make it possible to provide a more conversational style of programming

Future Work

• Mypy extension to validate scripts. For example, prove that a script shouldn't fail due to missing context_data for any step in the script.
• Dry run execution of steps
• DAG derivation for scripts
• Parallel evaluation for independent up to a join for DAG legs of a script.
• Diagram output for script DAGs.

Setup for Development

poetry install