lua: Add wezterm.action_callback to help define key callbacks

[bew]

Following up on https://matrix.to/#/!PirwUBcuIlTXwNveYz:matrix.org/$ets1eEk2ixZ3MgxHLrrpOoo2Rg3VI6Cg4z82IYxsOqA?via=matrix.org

I couldn't find a way to get the filename/linenumber of the call to use it for the event name without trying to use unsafe code.
It's actually not that bad, because as error in the callback will show a traceback with correct filename/linenumber.

🙃

[wez]

What do you think about adjusitng the custom events example below to use the new helper?

[bew]

I'm not sure, I think it's important to have an example using wezterm.on and wezterm.action{EmitEvent=...} explicitely, in case one wants to do something specific that would not be supported by wezterm.action_callback (like using the event id in another custom action, to emit it manually with wezterm.emit(...)).

I can write another simpler example below it though to show its usage in this doc file?
(the same as in the docs for wezterm.action_callback ? or the same example as below, but without the comments ?)

[wez]

How about both in the same example? If the line starting wezterm.on("trigger-vim-with-scrollback", function(window, pane) becomes a helper function definition, rather than a closure: function trigger_vim_with_scrollback(window, pane),
then we could show the new action_callback example first:

return {
  keys = {
    {key="E", mods="CTRL",
      action=wezterm.action_callback(function(win, pane)
           trigger_vim_with_scrollback(win, pane)
      end)
    }
}

then show the older/discrete way as an alternative:

wezterm.on("trigger-vim-with-scrollback", trigger_vim_with_scrollback)
return {
  keys = {
    {key="E", mods="CTRL",
      action=wezterm.action{EmitEvent="trigger-vim-with-scrollback"}},
  }
}

[wez]

Looks good, thanks! What do you think about expanding the examples to show it off?