I think we need to apply the output inspection method here so the copied output will be closer to what the users may expect.

For example, the output here by default will be the to_s result of the evaluation result, but IRB's default output inspector pretty prints the result inspect.

Additionally, we need to make sure colorizing is NOT applied to the copied value.

The problem with using the pretty printer is that colorizing output is hardcoded into it, and I don't think we want it in our clipboard.

Unless there's a pretty printer that I've missed, the options are:

1. Grab colorized output, strip color before copying. Least invasive, and will respect the currently configured inspector.
2. Install a new pretty printer analogous to the default color printer that does basically the same thing but doesn't colorize output. Don't like this one because we're conflating two concepts and hardcoding a command to use a specific kind of inspection method.
3. Like above, color_printer.rb to accept a parameter that turns colorizing on / off. Most invasive.

I like 1, but will defer.

Should we also have return if defined?(@clipboard_program) so we don't need to reevaluate the presence of the executables?

I updated it to be @clipboard_program ||=, but it looks like the command is re-instantiated each time so it doesn't matter. I could cache the value elsewhere (say, the class), but that has a subtle bug where changes to IRB.conf[:CLIPBOARD_PROGRAM] won't reflect once this has been computed.

Unsure what the behavior here should be. Setting this env var overrides the other clipboard programs we use, so right now this would cause copy to stop working.

However, we could just as easily interpret '' to mean "fall back to pbcopy".

Does the documentation need to be updated anywhere other than here and the man page?

Currently, copy typo will show this COPY_COMMAND warning message.
I think this message should be placed inside def copy_to_clipboard

Updated! Here's how it works now:

λ  irb → λ git sin.add-copy-command → ./bin/console
irb(main):001> copy typo
Error: undefined local variable or method `typo' for main
irb(main):002> copy 5
Copied to system clipboard
irb(main):003> IRB.conf[:COPY_COMMAND] = 'lulz'
=> "lulz"
irb(main):004> copy 5
No such file or directory - lulz
Is IRB.conf[:COPY_COMMAND] set to a bad value?
irb(main):005>