readline support not guaranteed without rb-readline

[cainlevy]

problem:

On Ubuntu 14.04, if libreadline-dev is not installed prior to using rbenv to compile ruby, then readline will not be available:

$ irb
irb(main):001:0> require 'byebug'
LoadError: cannot load such file -- readline

possible solutions:

• update readme to advise ubuntu users to run sudo apt-get install libreadline-dev before rbenv install
• add rb-readline as a dependency

[deivid-rodriguez]

Thanks for the report, I'll have a look and decide what to do.

[deivid-rodriguez]

@cainlevy Do you have any preferred solution for this? I think the better way would be to add rb-readline as a dependency but I'm interested in your opinion.

[cainlevy]

I'm not sure what the tradeoffs are, honestly. I tried to think of another popular REPL that might use readline and found this in Pry:

https://github.com/pry/pry/blob/5101cd4e34d905e10a218b01fb355668bf2fec21/lib/pry/config/default.rb#L150-L160

[deivid-rodriguez]

Let's find out! :)

[kamen-hursev]

The problem that @cainlevy describes is valid indeed with Ubuntu, however using rb-readline leads to other problems. For example pressing ctrl+left arrow results in ;5D instead of going to the beginning of the word. To be honest I couldn't really understand why this happens and how to fix it, and it was much easier to recompile ruby after installing libreadline-dev.

@deivid-rodriguez, I think a better solution will be adding a readme section or a descriptive error message, than depending on rb-readline when some of the users don't really need this gem.

[deivid-rodriguez]

@kamen-hursev Yep, I'm experiencing more problems than before after including rb-readline... :(

I'll remove it again and do what pry does (show a help message whenever requiring readline fails). And then release another minor version.

[knu]

After upgrading byebug I see many problems occur in a Pry session because of rb-readline, which seemingly cannot handle multi-byte characters properly. Literal strings containing multi-byte characters are now regarded as ASCII-8BIT instead of the default encoding (UTF-8), the multi-byte characters after colorization (syntax highlighting) are all garbled, and the terminal often gets stuck in a completely unusable state especially when pry enters a nested session. I've never seen these problems with the native readline library.
I'd really appreciate if this got reverted soon. 🙏

[deivid-rodriguez]

Done!

[knu]

Thanks! That saved me.

[jerefrer]

@kamen-hursev I'm having the same issue about ctrl+left arrow resulting in 5D but without using rb-readline. I tried recompiling Ruby after rvm pkg install readline, I tried recompiling using rvm reinstall ruby-2.0.0-p643 -C --with-readline-dir=~/.rvm/usr/ but none of this worked. As you can see I'm using RVM, and I'm on Archlinux.

When using debugger there is no such issue.

Do you have any idea how to make it work ? I'm so used to those shortcuts to navigate through text that it's very frustrating ...

[kamen-hursev]

Sorry, @jerefrer, but I don't think I can help you with this. This issue was fixed with byebug.
It might be that you have rb-readline as dependency of another gem or you might try to install libreadline-dev with the package manager of the OS. I use rbenv with ruby-build and I'm not sure what is supposed to be done with rvm.

[pathann]

@jerefrer with rvm and arch linux i got to work by simply installing gem rb-readline and adding it to the gemifle

[jerefrer]

@pathann Nope, doesn't work ... Thanks for trying :)
Which versions are you using ? (Ruby, Rails, Byebug, rb-readline, ...)

[mehta]

To fix this (for OSX, tested on Sierra), run following command in your shell -

ln -s /usr/local/opt/readline/lib/libreadline.dylib /usr/local/opt/readline/lib/libreadline.6.dylib

[pancutan]

Thanks guys.
Provided solution of add rb-readline as dependency of pry-byebug, works also very well on Archlinux / Manjaro. I was worried because on this distros there are not readline-dev package as Ubuntu does.

Cheers up!