Pry's command history malfunctions when pry-coolline's active

[pabloh]

Where using pry (0.10.0) with pry-coolline (0.2.4) and cooline (0.4.4), you need to push the up arrow button twice (instead of once) to get the last entered expression, like there was always an extra empty entry at the command history.

This is happening to me using ruby 2.1.2p95 (2014-05-08 revision 45877) [x86_64-linux].

[clessg]

Same problem here.

[anothermh]

This appears to be a problem because both the coolline gem and the pry gem are writing to the same .pry_history file:

• When pry-coolline invokes coolline it passes in the Pry.config.history.file file as a configuration option:

  pry-coolline/lib/pry-coolline/wrapper.rb

  Line 35 in 4759991

  cool.history_file = File.expand_path(Pry.config.history.file)

• When coolline's readline method is called, it will eventually call save_line: https://github.com/Mon-Ouie/coolline/blob/0ced8fc48dd3e62bc1b0cd8e819197424aac3b32/lib/coolline/coolline.rb#L259
• save_line writes back to Pry.config.history.file: https://github.com/Mon-Ouie/coolline/blob/0ced8fc48dd3e62bc1b0cd8e819197424aac3b32/lib/coolline/history.rb#L63-L66

Since both pry and coolline are writing to the history file, you appear to have to up-arrow twice to get to the last command, but it is actually first reading the entry from pry, and second reading the entry from coolline. You can confirm this with a simple monkey-patch to https://github.com/Mon-Ouie/coolline/blob/0ced8fc48dd3e62bc1b0cd8e819197424aac3b32/lib/coolline/history.rb#L64: @io.puts "#{self[-1]}-coolline" will force coolline to append -coolline to the entry that it saves to the history.

Either way, the fix is to monkey-patch either coolline (so it doesn't try to save the history file at all) or pry-coolline (so it passes in a null file for the history, e.g., cool.history_file = File.open(File::NULL, "w") at https://github.com/pry/pry-coolline/blob/master/lib/pry-coolline/wrapper.rb#L35).

I can't see why either pry-coolline or coolline need access to the pry history to be able to serve their intended purposes here, but there may be context that I am missing that @banister can explain.

[anothermh]

I looked into this more last night and was wrong about it. Ultimately, since both coolline and pry are going to try to write to the history file, I resolved it by editing my .pryrc file to include Pry.config.history.should_save = false if defined?(PryCoolline) so pry doesn't attempt to write to the history if pry-coolline is enabled. Now only coolline writes to the history file, and double-entries have been stopped.