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> Basically, I don't think there is too much chance to find a valid use for this behavior, but it is very hard to prevent it without complicating the language s

by twic 6y ago

> Basically, I don't think there is too much chance to find a valid use for this behavior, but it is very hard to prevent it without complicating the language significantly. One approach is to provide a mechanism for cleanup that doesn't require the object to still be alive. Java has phantom references for this: https://docs.oracle.com/en/java/javase/11/docs/api/java.base/java/lang/ref/PhantomReference.html https://docs.oracle.com/en/java/javase/11/docs/api/java.base... https://stackoverflow.com/a/43659951/116639 https://stackoverflow.com/a/43659951/116639 And i learn that Smalltalk introduced the "ephemeron", which is now present in some other languages: https://en.wikipedia.org/wiki/Ephemeron https://en.wikipedia.org/wiki/Ephemeron

tsimionescu 6y ago
Sure, there are other possible cleanup mechanisms, and I believe Java is depreciating finalizers in favor of those other mechanisms. My point was only about finalizers themselves: a language with the finalizer mechanism I was describing above would need to add a lot of features to prevent finalized objects from becoming reachable again.
masklinn 6y ago
> One approach is to provide a mechanism for cleanup that doesn't require the object to still be alive. Java has phantom references for this: Java has pretty much deprecated finalizers due to how non-deterministic their run is. Modern java uses try-with-resources blocks which… are the exact same thing as Python's with.