Populate history from external source.

[piotrmurach]

@roscom suggested in tty-prompt issue "Secondly, I currently manage the history in a redis cache, outside of rb-readline which is then available to all users. On session start up, the REPL currently populates rb-readline history from the redis cache. That would be a handy feature to be able to do that in your tty-* modules."

[logicminds]

I too have a REPL and wish to write a history file and load it back when the user restarts the REPL. The ability to pre-populate the history with a file or proc would be a nice addition.

[piotrmurach]

Hi Corey,

Thanks for using tty-reader and expressing enthusiasm for this feature. I'm currently working on releasing tty-prompt and pastel gems and have more things on my open-source plate to get done. So I'd love it if you could work on this feature and submit PR.

There is already a history file that saves lines in memory. The way I imagine this working is by having an argument in TTY::Reader::History, let's call it source, that would expose some generic APIs for reading and writing. And then have a specific source like TTY::Reader::Source::File that would know how to deal with files loading and retrieval. This way we would pave the way for future extensions like HTTP, DB and other sources. Any thoughts?