cli args support optional types

src/Window.zig

@@ -150,7 +150,7 @@ pub fn create(alloc: Allocator, loop: libuv.Loop, config: *const Config) !*Windo
     errdefer pty.deinit();
 
     // Create our child process
-    const path = (try Command.expandPath(alloc, "sh")) orelse
+    const path = (try Command.expandPath(alloc, config.command orelse "sh")) orelse
         return error.CommandNotFound;
     defer alloc.free(path);
 

src/cli_args.zig

@@ -42,7 +42,13 @@ fn parseIntoField(comptime T: type, dst: *T, key: []const u8, value: ?[]const u8
     inline for (info.Struct.fields) |field| {
         if (mem.eql(u8, field.name, key)) {
             @field(dst, field.name) = field: {
-                const Field = field.field_type;
+                // For optional fields, we just treat it as the child type.
+                // This lets optional fields default to null but get set by
+                // the CLI.
+                const Field = switch (@typeInfo(field.field_type)) {
+                    .Optional => |opt| opt.child,
+                    else => field.field_type,
+                };
                 const fieldInfo = @typeInfo(Field);
 
                 // If the type implements a parse function, call that.
@@ -137,6 +143,18 @@ test "parseIntoField: bool" {
     try testing.expectEqual(false, data.a);
 }
 
+test "parseIntoField: optional field" {
+    const testing = std.testing;
+
+    var data: struct {
+        a: ?bool = null,
+    } = .{};
+
+    // True
+    try parseIntoField(@TypeOf(data), &data, "a", "1");
+    try testing.expectEqual(true, data.a.?);
+}
+
 test "parseIntoField: struct with parse func" {
     const testing = std.testing;
 

src/config.zig

@@ -6,6 +6,10 @@ pub const Config = struct {
 
     /// Foreground color for the window.
     foreground: Color = .{ .r = 0xFF, .g = 0xA5, .b = 0 },
+
+    /// The command to run, usually a shell. If this is not an absolute path,
+    /// it'll be looked up in the PATH.
+    command: ?[]const u8 = null,
 };
 
 /// Color represents a color using RGB.