bundle exec pry起動時のエラーへの対処策

bundle exec pry を実行した際に、次のようなエラーが発生したので対処策をご紹介します。

エラー発生

$ bundle exec pry
Sorry, you can't use Pry without Readline or a compatible library.
Possible solutions:
 * Rebuild Ruby with Readline support using `--with-readline`
 * Use the rb-readline gem, which is a pure-Ruby port of Readline
 * Use the pry-coolline gem, a pure-ruby alternative to Readline
bundler: failed to load command: pry (/Users/araky/.rbenv/versions/2.4.3/bin/pry)
LoadError: dlopen(/Users/xxxx/.rbenv/versions/2.4.3/lib/ruby/2.4.0/x86_64-darwin17/readline.bundle, 9): Library not loaded: /usr/local/opt/readline/lib/libreadline.7.dylib
  Referenced from: /Users/xxxx/.rbenv/versions/2.4.3/lib/ruby/2.4.0/x86_64-darwin17/readline.bundle
  Reason: image not found - /Users/xxxx/.rbenv/versions/2.4.3/lib/ruby/2.4.0/x86_64-darwin17/readline.bundle

$ bundle exec pry

Sorry, you can't use Pry without Readline or a compatible library.

Possible solutions:

* Rebuild Ruby with Readline support using `--with-readline`

* Use the rb-readline gem, which is a pure-Ruby port of Readline

* Use the pry-coolline gem, a pure-ruby alternative to Readline

bundler: failed to load command: pry (/Users/araky/.rbenv/versions/2.4.3/bin/pry)

LoadError: dlopen(/Users/xxxx/.rbenv/versions/2.4.3/lib/ruby/2.4.0/x86_64-darwin17/readline.bundle, 9): Library not loaded: /usr/local/opt/readline/lib/libreadline.7.dylib

Referenced from: /Users/xxxx/.rbenv/versions/2.4.3/lib/ruby/2.4.0/x86_64-darwin17/readline.bundle

Reason: image not found - /Users/xxxx/.rbenv/versions/2.4.3/lib/ruby/2.4.0/x86_64-darwin17/readline.bundle

OS X ： 10.13.2（17C88）

Ruby：2.4.3p205

発生日：2020/3/20

対処策

$ ln -s /usr/local/opt/readline/lib/libreadline.8.0.dylib /usr/local/opt/readline/lib/libreadline.7.dylib

1	$ ln -s /usr/local/opt/readline/lib/libreadline.8.0.dylib /usr/local/opt/readline/lib/libreadline.7.dylib

これで正常に起動するようになりました。

$ bundle exec pry
[1] pry(main)>

1 2	$ bundle exec pry [1] pry(main)>

Sorry, you can't use Pry without Readline or a compatible library.でpryが起動しなくなった時の対処法

原因

おそらく、次の記事で起きた諸問題と同じく、python3をhomebrewでインストールした際に、homebrew updateかupgradeが走ってしまったか、自分で実行してしまったのがきっかけで起きています。readlineが意図せずアップグレードて、ファイル名が変わったため、参照が外れてしまったのだと推察します。