Dynamic ArgumentParser

staged-script provides parsing methods to construct an argparse.ArgumentParser and then use it in parsing the command line arguments passed to your script. What’s provided in the base class only provides and parses arguments specific to StagedScript itself, but it’s intended to be extended by subclasses. The usage of the functools.cached_property() decorator under the hood means the subclass parser will be evaluated, and unrolled, when it’s first used.

Note

This even allows for the creation of a complex hierarchy of StagedScript derivatives, where each class’s parser() and parse_args() methods extend the corresponding methods of its parent.

The base class provides the following arguments:

• --stage: Which stages to run. The available choices are automatically populated by the stages defined in the subclass.

• For each stage defined:

  • --STAGE-retry-attempts: How many times to retry the stage.

  • --STAGE-retry-delay: How long to delay before retrying.

  • --STAGE-retry-timeout: How long before giving up.

  Note

  These arguments are also captured in class attributes, in case subclass developers want to modify them (e.g., suppress them when they’re not applicable).

• --dry-run: Don’t actually run commands, just print them.