fix: change the behavior of printf in string op.

- add compiler hint for checking the arguments of printf.
- change the return value of printf. from std::expected to normal value. use C++ exception to indicate error.
	* the error of printf usually caused by programmer. so it can be found when testing program.
	* so i use std::logic_error to indicate this and programmer should fix this before releasing program.
- change the use of encoding convertion. for those cases that convertion must be safe, we unwrap it directly.

src/yycc/carton/clap/option.cpp

@@ -0,0 +1,5 @@
+#include "option.hpp"
+
+namespace yycc::carton::clap::option {
+    
+}

src/yycc/carton/clap/option.hpp

@@ -0,0 +1,85 @@
+#pragma once
+#include "types.hpp"
+#include "../../macro/class_copy_move.hpp"
+#include "../../string/op.hpp"
+#include <optional>
+#include <stdexcept>
+#include <format>
+#include <string>
+
+#define NS_YYCC_CLAP_TYPES ::yycc::carton::clap::types
+
+namespace yycc::carton::clap::option {
+
+    class Option {
+    public:
+        Option(std::optional<std::u8string_view> short_name,
+               std::optional<std::u8string_view> long_name,
+               std::optional<std::u8string_view> value_hint,
+               const std::u8string& description) :
+            short_name(short_name), long_name(long_name), value_hint(value_hint), description(description) {
+            if (!short_name.has_value() && !long_name.has_value()) {
+                throw std::logic_error("must have at least one name, short or long name");
+            }
+
+            if (short_name.has_value()) {
+                const auto& short_name_value = short_name.value();
+                if (!legal_short_name(short_name_value)) {
+                    throw std::logic_error(std::format("invalid short name {}", short_name_value));
+                }
+            }
+            if (long_name.has_value()) {
+                const auto& long_name_value = long_name.value();
+                if (!legal_long_name(long_name_value)) {
+                    throw std::logic_error(std::format("invalid long name {}", long_name_value));
+                }
+            }
+        }
+        ~Option() {}
+        YYCC_DEFAULT_COPY_MOVE(Option)
+
+    public:
+        std::optional<std::u8string_view> get_short_name() const { return this->short_name; }
+        std::optional<std::u8string_view> get_long_name() const { return this->long_name; }
+        std::optional<std::u8string_view> get_value_hint() const { return this->value_hint; }
+        std::u8string_view get_description() const { return this->description; }
+
+        std::u8string to_showcase_name() {
+            namespace op = ::yycc::string::op;
+
+            if (short_name.has_value()) {
+                if (long_name.has_value()) {
+                    
+                } else {
+                
+                }
+            } else {
+                if (long_name.has_value()) {
+                    op::printf
+                } else {
+                    throw std::runtime_error("both long name and short name are empty");
+                }
+            }
+        }
+
+    private:
+        static bool legal_short_name(const std::u8string_view& name) {
+            if (name.empty()) return false;
+            if (name.starts_with(NS_YYCC_CLAP_TYPES::DASH)) return false;
+            return true;
+        }
+        static bool legal_long_name(const std::u8string_view& name) {
+            if (name.empty()) return false;
+            return true;
+        }
+
+    private:
+        std::optional<std::u8string> short_name;
+        std::optional<std::u8string> long_name;
+        std::optional<std::u8string> value_hint;
+        std::u8string description;
+    };
+
+} // namespace yycc::carton::clap::option
+
+#undef NS_YYCC_CLAP_TYPES

src/yycc/carton/clap/types.hpp

@@ -0,0 +1,19 @@
+#pragma once
+#include <expected>
+#include <string_view>
+
+namespace yycc::carton::clap::types {
+
+    enum class ClapError {
+
+    };
+
+    template<typename T>
+    using ClapResult = std::expected<T, ClapError>;
+
+    inline constexpr std::u8string_view DASH = u8"-";
+    inline constexpr std::u8string_view DOUBLE_DASH = u8"--";
+
+    using Token = size_t;
+
+} // namespace yycc::carton::clap::types