Updated Empty Value Behavior

- Changed the `setEmpty()` method of Values to no longer erases a Value's default value.
- Updated the GetConfig in Command to allow library users to specify a status filter for the underlying Value.
- Updated `getVals()` to include these new features.

examples/covademo.zig

@@ -545,7 +545,7 @@ pub const setup_cmd: CommandT = .{
             .description = "A boolean value for the command.",
             .set_behavior = .Multi,
             .max_entries = 10,
-            .parse_fn = Value.ParsingFns.Builder.altBool(&.{ "true", "t", "yes", "y" }, &.{ "false", "f", "no", "n", "0" }, .Error),
+            .parse_fn = Value.ParsingFns.Builder.altBool(&.{ "true", "t", "yes", "y", "1" }, &.{ "false", "f", "no", "n", "0" }, .Error),
         }),
         ValueT.ofType(u64, .{
             .name = "cmd_u64",
@@ -629,7 +629,7 @@ pub fn main() !void {
     );
     var main_opts = try main_cmd.getOpts(.{});
     if (main_opts.get("string_opt")) |str_opt| strOpt: {
-        if (str_opt.val.isEmpty()) {
+        if (str_opt.val.isEmpty() and str_opt.val.isSet()) {
             log.debug("This Option was set, but intentionally left empty.", .{});
             break :strOpt;
         }

src/Command.zig

@@ -419,6 +419,14 @@ pub fn Custom(comptime config: Config) type {
         pub const GetConfig = struct{
             /// An optional Argument Group to filter the returned Options or Values.
             arg_group: ?[]const u8 = null,
+            /// A filter for the status of an Option or Value
+            status: StatusFilter = .set_or_default,
+
+            pub const StatusFilter = enum {
+                set,
+                set_or_default,
+                all,
+            };
         };
 
         /// Argument Groups Types for `checkGroup()`.
@@ -492,7 +500,11 @@ pub fn Custom(comptime config: Config) type {
                     const opt_group = opt.opt_group orelse continue;
                     if (!mem.eql(u8, conf_group, opt_group)) continue;
                 }
-                if (!opt.val.isSet() and !opt.val.hasDefault()) continue;
+                switch (get_config.status) {
+                    .set => if (!opt.val.isSet()) continue,
+                    .set_or_default => if (!opt.val.isSet() and !opt.val.hasDefault()) continue,
+                    else => {},
+                }
                 try map.put(opt.name, opt);
             }
             return map;
@@ -632,6 +644,11 @@ pub fn Custom(comptime config: Config) type {
                     const val_group = val.valGroup() orelse continue;
                     if (!mem.eql(u8, conf_group, val_group)) continue;
                 }
+                switch (get_config.status) {
+                    .set => if (!val.isSet()) continue,
+                    .set_or_default => if (!val.isSet() and !val.hasDefault()) continue,
+                    else => {},
+                }
                 try map.put(val.name(), val); 
             }
             return map;

src/Value.zig

@@ -350,7 +350,6 @@ pub fn Typed(comptime SetT: type, comptime config: Config) type {
         /// This is intended to be used with Options.
         pub fn setEmpty(self: *const @This()) !void {
             if (!self.is_empty) return error.NotEmpty;
-            if (@constCast(self).default_val) |_| @constCast(self).default_val = null;
             @constCast(self).is_set = true;
         }