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Automatic Cleaning

StepUp follows the same cleanup strategy as tup: If a step is removed or modified so that an output file is no longer created, StepUp will remove this output. This is also similar to Ninja’s cleandead command, but it is enabled by default in StepUp.

Sometimes, it can be helpful to postpone the cleanup until you are sure that the output files are no longer needed. This can be done in one of two ways:

  1. Add the --no-clean option to the stepup boot command. This will prevent StepUp from removing any output files.
  2. Block some steps by adding the block=True argument to the step() function in your plan.py script.

The main advantage of automatic cleaning is that it eliminates potential bugs and confusion related to old output files that are no longer relevant.

Try the Following

To illustrate the automatic cleaning, take the files from the example copy and mkdir and start StepUp in interactive mode. Make the following changes and rerun the affected steps after each point by pressing r in the terminal:

  • Change the directory sub/ to foo/ in plan.py. Rerunning StepUp will not only create foo/ and foo/hello.txt. After completing all pending steps, sub/ and sub/hello.txt will be removed.

  • Change all occurrences of hello.txt in plan.py to hi.txt. Rerunning StepUp will not only create hi.txt and foo/hi.txt. After completing all pending steps, hello.txt and foo/hello.txt will be removed.

  • Undo all changes and run StepUp again. You should end up with the original output without any remnants from the previous two steps.