Issue #13799 has been updated by shevegen (Robert A. Heiler). Interesting. https://ruby-doc.org/core-2.4.1/ENV.html does not mention #dup so perhaps this comes from Hash or some other upstream object? I also can not quite think of a use case for .dup there, perhaps someone can explain why ENV has it? On a side note, does anyone know why the documentation above does not mention #dup? ---------------------------------------- Bug #13799: ENV.dup returns a plain Object https://bugs.ruby-lang.org/issues/13799#change-66132 * Author: sylvain.joyeux (Sylvain Joyeux) * Status: Open * Priority: Normal * Assignee: * Target version: * ruby -v: 2.1.9, 2.2.5, 2.3.3, 2.4.1 * Backport: 2.2: UNKNOWN, 2.3: UNKNOWN, 2.4: UNKNOWN ---------------------------------------- I was doing ENV.dup to get a copy of the environment that can be modified without affecting ENV. However, ENV.dup returns a plain Object ~~~ irb(main):005:0> ENV.dup => #<Object:0x00000002024fc0> irb(main):006:0> ENV.dup['PATH'] NoMethodError: undefined method `[]' for #<Object:0x000000020446e0> from (irb):6 from /home/doudou/.rbenv/versions/2.4.1/bin/irb:11:in `<main>' irb(main):007:0> ~~~ The only way I found to get a copy is Hash[ENV] -- https://bugs.ruby-lang.org/ Unsubscribe: <mailto:ruby-core-request / ruby-lang.org?subject=unsubscribe> <http://lists.ruby-lang.org/cgi-bin/mailman/options/ruby-core>