A settings file

Keep the choices of your shell in a plain TOML file that anyone can edit, with types, defaults and live updates, and change them from the shell itself or from a terminal. A settings file is one declaration: state name from "file.toml" { fields }.

#The files

// bar.strand: the bar's choices live in prefs.toml beside this file
state prefs from "prefs.toml" {
  seconds: bool = false; position: Edge = top; accent: color = #7aa2f7
}
use palette material(seed: prefs.accent, dark: system.dark)

bar Top {
  edge: prefs.position; height: 32
  bg: $surface; font: $font.ui; color: $fg
  split { pad: 0, $space.3
    center { text clock.format(prefs.seconds ? "%H:%M:%S" : "%H:%M") }
    end {
      button prefs.seconds ? "Hide seconds" : "Show seconds" {
        on click { prefs.seconds = !prefs.seconds }
      }
    }
  }
}

A settings declaration at the top of a file belongs to that file, as any top-level state does; export state prefs from … would let other files read it as bar.prefs.

Here it is before there is a settings file. A click on the button sets prefs.seconds, and the clock shows them:

And the settings themselves, which you can leave out: a missing file gives every field its default.

# The bar's choices. Strand keeps these comments when it writes.
seconds = true
position = "bottom"
accent = "#e06c75"

#How it works

• Each field is name: type = default, read as prefs.seconds. A relative path is beside your config; ~/… is in your home directory.

• Edits apply live, field by field. Save the TOML file and the bar follows: the clock shows seconds, the bar moves to the bottom edge, the colours spring to the new accent.

• A bad value keeps that field's last good value, with a diagnostic; the other fields still apply. A TOML syntax error keeps every last good value. A line you delete goes back to its default.

• It is two-way. The button assigns prefs.seconds, and Strand writes the file, keeping its comments, spacing and order. A <-> binding writes it the same way. Writes are saved after 250 ms of quiet.

• From a terminal, strand set writes a field, as the button does, and strand get reads it:

  strand set prefs.position top
  strand get prefs.accent
  

  With the file's name first, bar.prefs.position is the same field; when two files declare settings named prefs, only that form works.

• The value's type decides what the file may say: true or false for a bool, a quoted "#rrggbb" for a color, an enum's variant by name for an enum (position = "bottom").

#Where the file lives

Writes follow symbolic links and replace the file through a temporary file and a rename, so a settings file in a dotfiles repository stays a link. A file you cannot write, such as one in /nix/store, gets the write in an overlay in Strand's state directory instead, with a notice.

#Variations

• Controls bound to it. segmented { options: Edge; value: <-> prefs.position } is a picker for the edge, a segment for each of Edge's variants; options: [Edge.top, Edge.bottom] offers only those two. A field level: float = 0.5 takes slider { value: <-> prefs.level } the same way.
• Several files. Each state … from is its own file; give them different names (prefs, layout).