Bug #16647: Redefining $/ causes irb to misbehave

• Status: Closed
• Assignee: -
• Target version: -
• ruby -v: ruby 2.7.0p0 (2019-12-25 revision 647ee6f091) [x86_64-darwin19]
• Backport: 2.5: UNKNOWN, 2.6: UNKNOWN, 2.7: UNKNOWN

[mehagar (Michael Hagar)]

If I start irb and then do:

$/ = "asdf"

then every character I type shows a newline on the irb console. Previous versions of ruby do not have this behavior, and it is annoying.

[Eregon (Benoit Daloze)]

Out of curiosity, why do you overwrite $/?

My personal opinion is we should deprecate all these variables affecting default separators,
they tend to break any non-trivial program, not just IRB, and explicit seems always clearer.

[Hanmac (Hans Mackowiak)]

Related to https://bugs.ruby-lang.org/issues/14240

changing these variables is deprecated now, and it shows a warning

[aycabta (aycabta .)]

• Status changed from Open to Closed

It was a problem with Reline. I fixed it by https://github.com/ruby/reline/pull/129.

My personal opinion is we should deprecate all these variables affecting default separators,
they tend to break any non-trivial program, not just IRB, and explicit seems always clearer.

I think so, but...maybe, so many beginners use IRB to check Ruby's features.
It's just my opinion, and it was easy to fix. So I fixed it for beginners.

hanging these variables is deprecated now, and it shows a warning

Yes, @nobu (Nobuyoshi Nakada) said "I forgot it (#14240) to create Pull Request (https://github.com/ruby/ruby/pull/2920) even I created a branch." after I talked about this issue (#16647) to @nobu (Nobuyoshi Nakada).
I'll remove the fix of Reline after the global variables are completely removed.

[mehagar (Michael Hagar)]

Eregon (Benoit Daloze) wrote in #note-1:

Out of curiosity, why do you overwrite $/?

My personal opinion is we should deprecate all these variables affecting default separators,
they tend to break any non-trivial program, not just IRB, and explicit seems always clearer.

I was following along an example from the book "The Well Grounded Rubyist, 3rd edition", that was illustrating how IO objects iterate.