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Protected-bindings

Protected-bindings is a library for combining the ideas of lexical clean-up via unwind-protect and dynamic clean-up via finalization.

The main benefit of using this library is saving you the typing of using unwind-protect and tg:finalize. In order to properly use unwind-protect and finalization, you must establish this clean-up immediately after the bind in order to mitigate the risk of a condition transferring control out of your code and missing the clean-up. This means that you typically shouldn’t bind several things and then use one unwind-protect to clean them all up, even though this is a natural inclination. We provide an interface that will immediately institute the clean-up after the bind without the excessive syntactic overhead of multiple nested let and unwind-protect forms.

Interface

The interface is very simple. A single macro is defined, with-protected-bindings*, which provides a let* like interface with arbitrary extra forms after the value of each binding that specifies how to clean up the binding. This is typically taken as a lexical clean-up, setting up an unwind-protect form. However, if the first form in the clean-up code in the symbol :finalize, the following result of the immediately following form is taken to be a thunk that performs the clean up. All forms after that thunk are again used in the unwind protect clean up.

I may someday implement a with-protected-bindings for parallel bindings, the analog of let, for symmetry, but this really isn’t usually needed.

Dependencies

Only trivial-garbage. Any implementation that has finalization support should be supported.

Known issues

Issues that are found are dealt with in short order, but…

This software is very lightly tested and should be considered relatively immature. If you use it in your project, or are just trying it out and find a glaring mistake, I would appreciate you dropping a complaint in the issues section or by email.

License

BSD