From: "knu (Akinori MUSHA) via ruby-core" Date: 2024-08-03T18:22:05+00:00 Subject: [ruby-core:118786] [Ruby master Feature#20664] Add `before` and `until` options to Enumerator.produce Issue #20664 has been updated by knu (Akinori MUSHA). This proposal is based on the potential use cases I have experienced over the years. I've rarely seen a need for infinite sequences that can be defined with produce, and that is why I want to give produce() a feature-complete constructor. Almost all sequences have had clear and simple end conditions. Traversing a tree structure for ancestor or sibling nodes would be the most typical use case, and the predicates like `nil?` and `root?` are mostly enough. Type-based conditions and inclusion conditions are not much seen probably because sequences are likely to be homogeneous and there is rarely more than one or a range of terminal values. ---------------------------------------- Feature #20664: Add `before` and `until` options to Enumerator.produce https://bugs.ruby-lang.org/issues/20664#change-109341 * Author: knu (Akinori MUSHA) * Status: Open ---------------------------------------- Enumerator.produce provides a nice way to generate an infinite sequence but is a bit awkward to define how to end a sequence. It lacks a simple and easy way to produce typical finite sequences in an intuitive syntax. This proposal attempts to solve the problem by adding these two options to the method: - `before`: when provided, it is used as a predicate to determine if an iteration should end before a generated value gets yielded. - `until`: when provided, it is used as a predicate to determine if an iteration should end until after a generated value gets yielded. Any value that responds to `to_proc` and returns a `Proc` object is accepted in these options. A typical use case for the `before` option is traversing a tree structure to iterate over the ancestors or following/preceding siblings of a node. The `until` option can be used when there is a clear definition of the "last" value to yield. ```ruby enum = Enumerator.produce(File, before: :nil?, &:superclass) enum.to_a #=> [File, IO, Object, BasicObject] enum = Enumerator.produce(3, until: :zero?, &:pred) enum_to_a #=> [3, 2, 1, 0] ``` ---Files-------------------------------- 0001-Add-before-and-until-options-to-Enumerator.produce.patch (10.7 KB) -- https://bugs.ruby-lang.org/ ______________________________________________ ruby-core mailing list -- ruby-core@ml.ruby-lang.org To unsubscribe send an email to ruby-core-leave@ml.ruby-lang.org ruby-core info -- https://ml.ruby-lang.org/mailman3/lists/ruby-core.ml.ruby-lang.org/