Directory tracking in emacs julia-repl

Tooling
1

The following snippet for .julia/config/startup.jl implements directory, user, and host tracking for julia-repl.

# set up emacs directory, host, and user tracking for julia-repl
atreplinit() do repl
    if haskey(ENV, "INSIDE_EMACS") &&
        occursin(r",term:", ENV["INSIDE_EMACS"])
        # acquire REPL
        @eval import REPL
        # only initialize repl.interface if necessary
        if ! isdefined(repl, :interface)
            repl.interface = REPL.setup_interface(repl)
        end
        # install a new prompt_prefix
        repl.interface.modes[1].prompt_prefix = 
            ((old, user, host, cwd) ->
             (() ->
              ((ENV["LOGNAME"] != user ?
                "\033AnSiTu "*(user = ENV["LOGNAME"])*"\n" : "") *
               (gethostname() != host  ?
                "\033AnSiTh "*(host = gethostname())*"\n" :  "") *
               (pwd() != cwd           ?
                "\033AnSiTc "*(cwd = pwd())*"\n" :           "") *
               (isa(old, String) ? old : old()))))(
                   repl.interface.modes[1].prompt_prefix, "", "", ""
               )
    end
end
# end of set up emacs directory, host, and user tracking for julia-repl

It’s restricted to julia-repl by the test for occursin(r",term:", ENV["INSIDE_EMACS"], and it’s careful not to overwrite any previous modifications to repl.interface or prompt_prefix, but it won’t pick up subsequent changes to the color of the julia> prompt, and it’s vulnerable to some subsequent snippet blindly reinitializing repl.interface.

It’s been tested only on linux and mostly on recent versions of julia, I’m curious if it’s more generally useful.

2

Neat!