Bug #21089: Missing methods on enumerators created from Enumerator::product and Enumerator::Chain

• Status: Open
• Assignee: knu (Akinori MUSHA)
• Target version: -
• ruby -v: ruby 3.5.0dev (2025-01-26T08:52:22Z master d4a1a2780c) +PRISM [arm64-darwin24]
• Backport: 3.1: UNKNOWN, 3.2: UNKNOWN, 3.3: UNKNOWN, 3.4: UNKNOWN

[zetter (Chris Zetter)]

I was using Enumerator.product and noticed the enumerators it returned were missing the next method.

When looking at the source code, I saw all the stateful enumerator methods were missing (next, peek_values, peek, next_values, feed) as they were removed from the Enumerator::Product subclass with rb_undef_method.

This also applies to instances of Enumerator::Chain, it looks like the methods never worked and were removed in https://bugs.ruby-lang.org/projects/ruby-master/repository/git/revisions/68d028578a5975fe6c44d29c502615ff9af72927

Because the English documentation says Enumerator.product 'Generates a new enumerator object' and the documentation says it inherits from Enumerator I expected it to have the next method available. I can use .to_enum to make the next method available, but I'm not sure why I need to.

I'm unsure if this could be solved by making these available or the documentation could be improved.

[nobu (Nobuyoshi Nakada)]

• Related to Feature #18685: Enumerator.product: Cartesian product of enumerables added

[nobu (Nobuyoshi Nakada)]

• Assignee set to knu (Akinori MUSHA)