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Hairball is a plugin-able framework useful for static analysis of Scratch projects.

The paper and presentation slides for Hairball can be found at:

A Hairball demo web service is running and available at:

Hairball installation

With a proper python environment (one which has pip available), installation is as simple as pip install hairball. easy_install can also be used via easy_install hairball.

To install from source, first checkout this project and then navigate your command-line interface to the outer hairball directory that contains Then run python install.

Running Hairball

Once installed, to see how to use hairball run hairball --help. That will produce output similar to the following:

Usage: hairball -p PLUGIN_NAME [options] PATH...

PATH can be either the path to a scratch file, or a directory containing
scratch files. Multiple PATH arguments can be provided.

  --version             show program's version number and exit
  -h, --help            show this help message and exit
  -d DIR, --plugin-dir=DIR
                        Specify the path to a directory containing plugins.
                        Plugins in this directory take precedence over
                        similarly named plugins included with Hairball.
  -p PLUGIN, --plugin=PLUGIN
                        Use the named plugin to perform analysis. This option
                        can be provided multiple times.
  -k KURT_PLUGIN, --kurt-plugin=KURT_PLUGIN
                        Provide either a python import path (e.g, kelp.octopi)
                        to a package/module, or the path to a python file,
                        which will be loaded as a Kurt plugin. This option can
                        be provided multiple times.

Available Plugins

Below are a list of available plugins that can be used as the -p PLUGIN_NAME option:

  • blocks.BlockCounts
  • blocks.DeadCode
  • checks.Animation (not fully tested)
  • checks.BroadcastReceive
  • checks.SaySoundSync (not fully tested)
  • duplicate.DuplicateScripts
  • initialization.AttributeInitialization
  • initialization.VariableInitialization (not fully tested)

Note: The output for each plugin is not yet completely standardized. Please feel free to file any issues or make improvements and send pull requests.

Caching Support

The python Kurt package unfortunately is pretty slow to parse Scratch 1.4 (and similar) files. To remedy this situation, Hairball has built-in support for caching a serialized version of the Kurt object. On subsequent passes through the same data you should notice a TREMENDOUS speed improvement.

Note: At the moment the cache is unbounded, so keep an eye on your disk space. The cache location can be discovered by running:

python -c "import appdirs; print appdirs.user_cache_dir('Hairball', 'bboe')"


Hairball is a plugin-able framework useful for static analysis of Scratch projects.







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