Request: Add a command/control FIFO

[RibalGZ]

I Would like to see some kind of support to send and receive messages through a FIFO file, like the dwmfifo patch does for DWM: http://dwm.suckless.org/patches/dwmfifo

This would allow us to script the vis behavior using any language in a simpler way.

I think that a possible behavior could be like this one:

• Vis creates a tmp FIFO when a new client is opened.
• In config.h, the user can define a list of scripts, which would receive the related tmp file as a parameter.
• The FIFO output should be able to:
  • Send the keystrokes to the script.
  • Send events like INIT or WIN_OPEN.
• The FIFO input should be able to:
  • Set vis options.
  • Ask for vis info, like the current mode.
  • Execute keybindings.

[ghost]

Vis may get client-server design at some point. Maybe a FIFO could be the way to do this.

This can be relevant too: https://github.com/martanne/vis/issues/59

[martanne]

For starters FIFOs are unidirectional, we probably want to use Unix domain sockets for bidirectional communication.

I tend to think that a language agnostic RPC API is the the right way to tackle this. It could then be used to implement a textual protocol (as you seem to propose?), a FUSE or 9P based file system interface or whatever craziness you come up with.

Prerequisite for that is a global main loop and a sound model (or a conscious decision to ignore the problem) on how to handle concurrent changes. This was recently also touched on in #537. I'm not sure what yet another issue, besides those already linked, accomplishes?