23 lines
1.1 KiB
Org Mode
23 lines
1.1 KiB
Org Mode
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#+TITLE:Guile Weak References
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This is a simple little library that makes use of the weak hash table functionality in core Guile
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to hackily implement weak references, objects which weakly point to other objects.
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The interface is very simple:
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(make-weakref obj)
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- Create a weak reference, which will not count as a reference, so the object can be garbage collected
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(weakref-object obj)
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- Get the object, or #f if it has been garbage collected.
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* Implementation
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This is a very simple implementation. There's a globally incremented ID associated with each object, and
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the object is stored in two global weak hash tables, one id-to-object and another object-to-id. The weak
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reference is a record type that stores the ID and also a tombstone property to cache whether the object
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has been collected to avoid the need to look it up after that point.
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I created this because I needed an interface outside of the hash tables to refer to single objects instead
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of creating a bunch of weak dictionaries. Also, Guile Hoot does not yet support iteration through weak key
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hash tables, so this will allow me to create a list of weak refs to iterate over instead.
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