From: marcandre-ruby-core@... Date: 2020-11-11T17:55:01+00:00 Subject: [ruby-core:100793] [Ruby master Feature#17316] On memoization Issue #17316 has been updated by marcandre (Marc-Andre Lafortune). Memoization is tricky, not just for `nil`/`false` values. What about freezing that object? What about calling `Ractor.make_shareable` on it? I just released a small gem to deal with memoization that: - works with `nil`/`false` results. - works for methods accepting arguments - works for frozen objects - is Ractor-ready in that the object can be made Ractor-shareable. Gem is here: https://github.com/marcandre/ractor-cache Comments welcome :-) I think more strategies might be useful, for example accessing the cache via a Ractor/SharedHash, but haven't implemented that. ---------------------------------------- Feature #17316: On memoization https://bugs.ruby-lang.org/issues/17316#change-88436 * Author: sawa (Tsuyoshi Sawada) * Status: Open * Priority: Normal ---------------------------------------- I have seen so many attempts to memoize a value in the form: ```ruby @foo ||= some_heavy_calculation(...) ``` improperly, i.e., even when the value can potentially be falsy. This practice is wide spread, and since in most cases memoization is about efficiency and it would not be critical if it does not work correctly, people do not seem to care so much about correcting the wrong usage. In such case, the correct form would be: ```ruby unless instance_variable_defined?(:foo) @foo = some_heavy_calculation(...) end ``` but this looks too long, and perhaps that is keeping people away from using it. What about allowing `Kernel#instance_variable_set` to take a block instead of the second argument, in which case the assignment should be done only when the instance variable is not defined? ```ruby instance_variable_set(:foo){some_heavy_calculation(...)} ``` Or, if that does not look right or seems to depart from the original usage of `instance_variable_set`, then what about having a new method? ```ruby memoize(:foo){some_heavy_calculation(...)} ``` -- https://bugs.ruby-lang.org/ Unsubscribe: