allow other calculators

=

@@ -4,6 +4,7 @@
 # Calculator for use with rofi/dmenu(2)
 # Copying to the clipboard requires xclip
 
+
 copy_to_clipboard() {
   if [ "$XDG_SESSION_TYPE" = "wayland" ]; then
     wl-copy "$1"
@@ -23,6 +24,13 @@ usage() {
   echo "    = sqrt(4)"
   echo "    = c(2)"
   echo
+  echo "$(tput bold)change calculator:$(tput sgr0)"
+  echo
+  echo "By default it will be bc. To change it to another one use"
+  echo " --calculator argument"
+  echo
+  echo " = --calculator=<calculator_command>"
+  echo
   echo "$(tput bold)Force Rofi/dmenu(2):$(tput sgr0)"
   echo "By default, if rofi exists, it will be used. To force menu-calc to"
   echo "use one or the other, use the --dmenu argument"
@@ -48,12 +56,20 @@ do
     -d=*|--dmenu=*)
       menu=$(echo "$var" | cut -d'=' -f 2);
       ;;
+    --calculator=*)
+      calc=$(echo "$var" | cut -d'=' -f 2);
+    ;;
     --) break ;;
   esac
 done
 
+
+#set bc as default
+if [ -z "${calc}" ]; then
+  calc="bc -l"
+fi
 # Grab the answer
-answer=$(echo "$1" | bc -l | sed '/\./ s/\.\{0,1\}0\{1,\}$//')
+answer=$(echo "$1" | $calc | sed '/\./ s/\.\{0,1\}0\{1,\}$//')
 
 # Path to menu application
 if [ -z "${menu+1}" ]; then
@@ -83,9 +99,9 @@ done
 action=$(echo -e "Copy to clipboard\nClear\nClose" | $menu "$@" -p "= $answer")
 
 case $action in
-  "Clear") $0 "--dmenu=$menu" "--" "$@" ;;
+  "Clear") $0 "--dmenu=$menu" "--calculator=$calc" "--" "$@" ;;
   "Copy to clipboard") copy_to_clipboard "$answer" ;;
   "Close") ;;
   "") ;;
-  *) $0 "$answer $action" "--dmenu=$menu" "--" "$@" ;;
+  *) $0 "$answer $action" "--dmenu=$menu" "--calculator=$calc" "--" "$@" ;;
 esac

README.md

@@ -40,6 +40,8 @@ outputs = { ..., menucalc }: {
 };
 ```
 
+If you want to use fend as an backend just use the package menucalc-fend
+
 ### Arch Linux AUR
 
 [menu-calc](https://aur.archlinux.org/packages/menu-calc/)
@@ -86,3 +88,11 @@ By default, if `rofi` is installed, it will be used. You can force `menu-calc`
 to use `dmenu` or any other `dmenu`-like application:
 
     = --dmenu=dmenu
+
+### Change calculator backend
+
+By default [bc](https://www.gnu.org/software/bc/manual/html_mono/bc.html)
+is used, alternatively a custom command (e.g. [fend](https://github.com/printfn/fend))
+can be used instead
+
+    = --calculator=fend

flake.nix

@@ -10,8 +10,8 @@
   outputs = { self, nixpkgs, flake-utils }:
     (flake-utils.lib.eachDefaultSystem (system:
       let pkgs = import nixpkgs { inherit system; };
-      in rec {
-        packages.menucalc = pkgs.stdenv.mkDerivation rec {
+      derivation-attrs = backend_pkg: backend_cmd:
+ rec {
           pname = "menucalc";
           version = "v1.3.0";
 
@@ -29,11 +29,11 @@
           '';
 
           wrapperPath =
-            pkgs.lib.makeBinPath (with pkgs; [ bc rofi xclip wl-clipboard ]);
+            pkgs.lib.makeBinPath (with pkgs; [ backend_pkg rofi xclip wl-clipboard ]);
 
           fixupPhase = ''
             patchShebangs $out/bin
-            wrapProgram $out/bin/= --prefix PATH : "${wrapperPath}"
+            wrapProgram $out/bin/= --prefix PATH : "${wrapperPath}" --add-flags "--calculator=${backend_cmd}"
           '';
 
           meta = {
@@ -44,9 +44,12 @@
             platforms = with pkgs.lib.platforms; linux;
           };
         };
+      in rec {
+        packages.menucalc = pkgs.stdenv.mkDerivation (derivation-attrs pkgs.bc "bc -l");
+        packages.menucalc-fend = pkgs.stdenv.mkDerivation (derivation-attrs pkgs.fend "fend");
         packages.default = packages.menucalc;
 
         devShells.default =
-          pkgs.mkShell { packages = with pkgs; [ bc pre-commit shellcheck ]; };
+          pkgs.mkShell { packages = with pkgs; [ bc fend pre-commit shellcheck ]; };
       }));
 }

menu-calc.1

@@ -13,7 +13,7 @@ menu-calc \- A calculator for
 .BR menu-calc
 uses
 .BR bc (1)
-as the backend and will accept any operations
+(by default) as the backend and will accept any operations
 .BR bc (1)
 is able to do.
 The answer can be copied to the clipboard and used for further calculations
@@ -49,15 +49,16 @@ Examples of performing math operations in menu-calc:
 .TP
 Bind \fBdmenu\fR(1) with a variety of parameters to F4 in \fBi3wm\fR(1).
 .B bindsym F4 exec = --dmenu=dmenu -- -i -fn 'Isoveka Term 10' -dim 0.5 -l 3
-
+.TP
+use \fBfend\fR(1) instead of bc
+.B = --calculator=fend
 .SH OPTIONS
 .TP
 .B \-h
 show help
 .TP
-.B <bc-math-expression>
-Parameters to be passed to
-.BR bc (1) .
+.B <math-expression>
+Parameters to be passed to the configured calculator
 .TP
 .B --dmenu=<dmenu_executable>
 Set the dmenu-compatible executable. This can be used to force menu-calc to use
@@ -68,6 +69,9 @@ Parameters to be passed to
 .BR rofi (1)
 /
 .BR dmenu (1) .
+.TP
+.B --calculator=<calculator_command>
+Set the calculator command. Use this to change to another calculator backend.
 
 .SH AUTHOR
 Jonathan Sumner Evans <sumner.evans98 at gmail dot com>