bochs: configure it via module system

pkgs/by-name/bo/bochs/options.nix

@@ -0,0 +1,40 @@
+{
+  lib,
+  config,
+  stdenv,
+  _pkgs,
+  ...
+}:
+
+{
+  options = {
+    SDL2 = lib.mkOption {
+      type = lib.types.bool;
+      default = lib.meta.availableOn stdenv.hostPlatform _pkgs.SDL2;
+      description = ''
+        Enable SDL2 interface.
+      '';
+    };
+    X11 = lib.mkOption {
+      type = lib.types.bool;
+      default = lib.meta.availableOn stdenv.hostPlatform _pkgs.libX11;
+      description = ''
+        Enable X11 interface.
+      '';
+    };
+    term = lib.mkOption {
+      type = lib.types.bool;
+      default = lib.meta.availableOn stdenv.hostPlatform _pkgs.ncurses;
+      description = ''
+        Enable ncurses terminal interface.
+      '';
+    };
+    wx = lib.mkOption {
+      type = lib.types.bool;
+      default = lib.meta.availableOn stdenv.hostPlatform _pkgs.wxGTK32;
+      description = ''
+        Enable wxWidgets interface.
+      '';
+    };
+  };
+}

pkgs/by-name/bo/bochs/package.nix

@@ -18,13 +18,29 @@
   stdenv,
   wget,
   wxGTK32,
-  # Boolean flags
-  enableSDL2 ? true,
-  enableTerm ? true,
-  enableWx ? !stdenv.hostPlatform.isDarwin,
-  enableX11 ? !stdenv.hostPlatform.isDarwin,
+  _configuration ? {},
 }:
 
+let
+  eval = lib.evalModules {
+    modules = [
+      ./options.nix
+      _configuration
+      {
+        _module.args = {
+          inherit stdenv;
+          _pkgs = {
+            inherit SDL2 ncurses wxGTK32 libX11;
+          };
+        };
+      }
+    ];
+  };
+  enableSDL2 = eval.config.SDL2;
+  enableTerm = eval.config.term;
+  enableWx = eval.config.wx;
+  enableX11 = eval.config.X11;
+in
 stdenv.mkDerivation (finalAttrs: {
   pname = "bochs";
   version = "2.8";