sane-sysload: make the format CLI args friendlier

hosts/common/programs/conky/conky.conf

@@ -66,6 +66,7 @@ end
 if vars.percent ~= nil then
   bat_args = bat_args .. " --percent-suffix '" .. vars.percent .. "'"
 end
+bat_args = bat_args .. " {bat}"
 
 -- N.B.: `[[ <text> ]]` is Lua's multiline string literal
 conky.text = [[
@@ -73,8 +74,8 @@ ${color1}${shadecolor 707070}${font sans-serif:size=50:style=Bold}${alignc}${exe
 ${color2}${shadecolor a4d7d0}${font sans-serif:size=20}${alignc}${exec date +"%a %d %b"}${font}
 
 
-${color1}${shadecolor}${font sans-serif:size=22:style=Bold}${alignc}${execp @bat@ ]] .. bat_args .. [[ }${font}
-${color1}${shadecolor}${font sans-serif:size=20:style=Bold}${alignc}${texeci 600 @weather@ }${font}
+${color1}${shadecolor}${font sans-serif:size=22:style=Bold}${alignc}${execp sane-sysload ]] .. bat_args .. [[ }${font}
+${color1}${shadecolor}${font sans-serif:size=20:style=Bold}${alignc}${texeci 600 timeout 20 sane-weather }${font}
 
 
 ${color2}${shadecolor a4d7d0}${font sans-serif:size=16}${alignc}⇅ ${downspeedf wlan0}]] .. vars.kBps .. [[${font}

hosts/common/programs/conky/default.nix

@@ -16,11 +16,7 @@
       "sane-weather"
     ];
 
-    fs.".config/conky/conky.conf".symlink.target = pkgs.substituteAll {
-      src = ./conky.conf;
-      bat = "sane-sysload";
-      weather = "timeout 20 sane-weather";
-    };
+    fs.".config/conky/conky.conf".symlink.target = ./conky.conf;
 
     services.conky = {
       description = "conky dynamic desktop background";

pkgs/additional/sane-sysload/sane-sysload

@@ -1,7 +1,7 @@
 #!/usr/bin/env nix-shell
 #!nix-shell -i python3 -p "python3.withPackages (ps: [  ])"
 """
-usage: sane-sysload [options...]
+usage: sane-sysload [options...] formatstr
 
 pretty-prints a battery estimate (icon to indicate state, and a duration estimate)
 
@@ -11,6 +11,16 @@ options:
   --hour-suffix <string>:  use the provided string as an hours suffix
   --icon-suffix <string>:  use the provided string as an icon suffix
   --percent-suffix <string>:  use the provided string when displaying percents
+
+formatstr is a Python format string.
+variables available for formatting:
+- {bat_icon}
+- {bat_time}
+- {mem_icon}
+- {mem_pct}
+and some presets, encapsulating the above:
+- {bat}
+- {mem}
 """
 
 import argparse
@@ -266,6 +276,13 @@ class AllInfo:
     _mem: MemInfo | None
     _bat: BatteryInfo | None
 
+    @property
+    def bat(self) -> str:
+        return f"{self.bat_icon}{self.bat_time}"
+    @property
+    def mem(self) -> str:
+        return f"{self.mem_icon}{self.mem_pct}"
+
     @property
     def mem_icon(self) -> str:
         if self._mem is None: return ""
@@ -307,6 +324,17 @@ class AllInfo:
         else:
             return self._fmt.render_percent(self._bat.percent_charged)
 
+class LazyFormatter:
+    def __init__(self, obj: object, attr: str):
+        self.obj = obj
+        self.attr = attr
+
+    def __repr__(self) -> str:
+        return repr(getattr(self.obj, self.attr))
+
+    def __str__(self) -> str:
+        return str(getattr(self.obj, self.attr))
+
 def main() -> None:
     logging.basicConfig()
     logging.getLogger().setLevel(logging.INFO)
@@ -317,8 +345,7 @@ def main() -> None:
     parser.add_argument("--hour-suffix", default=SUFFIX_HR)
     parser.add_argument("--minute-suffix", default=SUFFIX_MIN)
     parser.add_argument("--percent-suffix", default=SUFFIX_PERCENT)
-    parser.add_argument("--template", default="{_.bat_icon}{_.bat_time}")
-    # parser.add_argument("--template", default="{_.mem_icon}{_.mem_pct}")
+    parser.add_argument("formatstr")
     args = parser.parse_args()
 
     if args.debug:
@@ -335,7 +362,14 @@ def main() -> None:
         MemInfo(),
         try_all_batteries(),
     )
-    print(args.template.format(_=info))
+    print(args.formatstr.format(
+      bat=LazyFormatter(info, "bat"),
+      bat_icon=LazyFormatter(info, "bat_icon"),
+      bat_time=LazyFormatter(info, "bat_time"),
+      mem=LazyFormatter(info, "mem"),
+      mem_icon=LazyFormatter(info, "mem_icon"),
+      mem_pct=LazyFormatter(info, "mem_pct"),
+    ))
 
 if __name__ == "__main__":
     main()