diff --git a/demo/alu.cpp b/demo/alu.cpp
index 08c4f00..563962d 100644
--- a/demo/alu.cpp
+++ b/demo/alu.cpp
@@ -1,131 +1,111 @@
-#include "../include/tools.h"
+#include "tools.h"
 #include <iostream>
-
-bool reset;
-bool ready;
+#include <unordered_map>
 
 // RISC-V
 enum class Opcode : dark::max_size_t {
-    ADD,
-    SUB,
-    SLL,
-    SRL,
-    SRA,
-    AND,
-    OR,
-    XOR,
-    SLT,
-    SLTU,
-    SGE,
-    SGEU,
-    SEQ,
-    SNEQ
+	ADD,
+	SUB,
+	SLL,
+	SRL,
+	SRA,
+	AND,
+	OR,
+	XOR,
+	SLT,
+	SLTU,
+	SGE,
+	SGEU,
+	SEQ,
+	SNEQ
 };
 
-
 // Normally, only wire can be used in the input.
 struct AluInput {
-    Wire <8> opcode;
-    Wire <1> issue;
-    Wire <32> rs1;
-    Wire <32> rs2;
+	Wire<8> opcode;
+	Wire<1> issue;
+	Wire<32> rs1;
+	Wire<32> rs2;
 };
 
 struct AluOutput {
-    Register <32> out;
-    Register <1> done;    
+	Register<32> out;
+	Register<1> done;
 };
 
-struct AluModule : AluInput, AluOutput {
-    using Tags = SyncTags<AluInput, AluOutput>;
-
-    void work() {
-        if (reset) {
-            done <= 0;
-        } else if(ready && issue) {
-            switch (static_cast <Opcode> (static_cast <unsigned> (opcode))) {
-                using enum Opcode;
-                case ADD:   out <= (rs1 + rs2); break;
-                case SUB:   out <= (rs1 - rs2); break;
-                case SLL:   out <= (rs1 << rs2); break;
-                case SRL:   out <= (rs1 >> rs2); break;
-                case SRA:   out <= (to_signed(rs1) >> to_unsigned(rs2));
-                case AND:   out <= (rs1 & rs2); break;
-                case OR:    out <= (rs1 | rs2); break;
-                case XOR:   out <= (rs1 ^ rs2); break;
-                case SLT:   out <= (to_signed(rs1) < to_signed(rs2)); break;
-                case SLTU:  out <= (rs1 < rs2); break;
-                case SGE:   out <= (to_signed(rs1) >= to_signed(rs2)); break;
-                case SGEU:  out <= (rs1 >= rs2); break;
-                case SEQ:   out <= (rs1 == rs2); break;
-                case SNEQ:  out <= (rs1 != rs2); break;
-                default: dark::debug::assert(false, "Invalid opcode");
-            }
-            done <= 1;
-        } else {
-            done <= 0;
-        }
-    }
-
+struct AluModule : dark::Module<AluInput, AluOutput> {
+	void work() override {
+		if (issue) {
+			switch (static_cast<Opcode>(static_cast<unsigned>(opcode))) {
+				using enum Opcode;
+				case ADD: out <= (rs1 + rs2); break;
+				case SUB: out <= (rs1 - rs2); break;
+				case SLL: out <= (rs1 << rs2); break;
+				case SRL: out <= (rs1 >> rs2); break;
+				case SRA: out <= (to_signed(rs1) >> to_unsigned(rs2));
+				case AND: out <= (rs1 & rs2); break;
+				case OR: out <= (rs1 | rs2); break;
+				case XOR: out <= (rs1 ^ rs2); break;
+				case SLT: out <= (to_signed(rs1) < to_signed(rs2)); break;
+				case SLTU: out <= (rs1 < rs2); break;
+				case SGE: out <= (to_signed(rs1) >= to_signed(rs2)); break;
+				case SGEU: out <= (rs1 >= rs2); break;
+				case SEQ: out <= (rs1 == rs2); break;
+				case SNEQ: out <= (rs1 != rs2); break;
+				default: dark::debug::assert(false, "Invalid opcode");
+			}
+			done <= 1;
+		}
+		else {
+			done <= 0;
+		}
+	}
 };
 
-signed main() {
-    AluModule alu;
+int main() {
+	std::string opstring;
 
-    std::string opstring;
+	max_size_t opcode;
+	max_size_t issue;
+	max_size_t rs1;
+	max_size_t rs2;
 
-    max_size_t opcode;
-    max_size_t issue;
-    max_size_t rs1;
-    max_size_t rs2;
-
-    ready = 1;
-
-    alu.opcode = [&]() { return opcode; };
-    alu.issue = [&]() { return issue; };
-    alu.rs1 = [&]() { return rs1; };
-    alu.rs2 = [&]() { return rs2; };
-
-    while (std::cin >> opstring) {
-        issue = 1;
-        std::cin >> rs1 >> rs2;
-        if (opstring == "add") {
-            opcode = static_cast <max_size_t> (Opcode::ADD);
-        } else if (opstring == "sub") {
-            opcode = static_cast <max_size_t> (Opcode::SUB);
-        } else if (opstring == "sll") {
-            opcode = static_cast <max_size_t> (Opcode::SLL);
-        } else if (opstring == "srl") {
-            opcode = static_cast <max_size_t> (Opcode::SRL);
-        } else if (opstring == "sra") {
-            opcode = static_cast <max_size_t> (Opcode::SRA);
-        } else if (opstring == "and") {
-            opcode = static_cast <max_size_t> (Opcode::AND);
-        } else if (opstring == "or") {
-            opcode = static_cast <max_size_t> (Opcode::OR);
-        } else if (opstring == "xor") {
-            opcode = static_cast <max_size_t> (Opcode::XOR);
-        } else if (opstring == "slt") {
-            opcode = static_cast <max_size_t> (Opcode::SLT);
-        } else if (opstring == "sltu") {
-            opcode = static_cast <max_size_t> (Opcode::SLTU);
-        } else if (opstring == "sge") {
-            opcode = static_cast <max_size_t> (Opcode::SGE);
-        } else if (opstring == "sgeu") {
-            opcode = static_cast <max_size_t> (Opcode::SGEU);
-        } else if (opstring == "seq") {
-            opcode = static_cast <max_size_t> (Opcode::SEQ);
-        } else if (opstring == "sneq") {
-            opcode = static_cast <max_size_t> (Opcode::SNEQ);
-        } else {
-            std::cout << "Invalid opcode" << std::endl;
-            issue = 0;
-        }
-
-        alu.work();
-
-        std::cout << to_unsigned(alu.out) << std::endl;
-        sync_member(alu);
-    }
+	dark::CPU cpu;
+	AluModule alu;
+	alu.opcode = [&]() { return opcode; };
+	alu.issue = [&]() { return issue; };
+	alu.rs1 = [&]() { return rs1; };
+	alu.rs2 = [&]() { return rs2; };
+	cpu.add_module(&alu);
 
+	std::unordered_map<std::string, Opcode> cmd2op = {
+			{"add", Opcode::ADD},
+			{"sub", Opcode::SUB},
+			{"sll", Opcode::SLL},
+			{"src", Opcode::SRL},
+			{"sra", Opcode::SRA},
+			{"and", Opcode::AND},
+			{"or", Opcode::OR},
+			{"xor", Opcode::XOR},
+			{"slt", Opcode::SLT},
+			{"sltu", Opcode::SLTU},
+			{"sge", Opcode::SGE},
+			{"sgeu", Opcode::SGEU},
+			{"seq", Opcode::SEQ},
+			{"sneq", Opcode::SNEQ}};
+	while (std::cin >> opstring) {
+		if (cmd2op.find(opstring) == cmd2op.end()) {
+			std::cout << "Invalid opcode" << std::endl;
+			issue = 0;
+		}
+		else {
+			issue = 1;
+			std::cin >> rs1 >> rs2;
+		}
+		opcode = static_cast<max_size_t>(cmd2op[opstring]);
+		cpu.run_once();
+		std::cout << "out: " << static_cast<unsigned int>(alu.out) << std::endl;
+		std::cout << "done: " << static_cast<unsigned int>(alu.done) << std::endl;
+	}
+	return 0;
 }
\ No newline at end of file
diff --git a/include/concept.h b/include/concept.h
index 6e1ef93..149cdb4 100644
--- a/include/concept.h
+++ b/include/concept.h
@@ -43,7 +43,9 @@ concept int_type = !has_length<_Tp> && implicit_convertible_to<_Tp, max_size_t>;
 
 template<typename _Lhs, typename _Rhs>
 concept bit_match =
-		(bit_type<_Lhs> && bit_type<_Rhs> && _Lhs::_Bit_Len == _Rhs::_Bit_Len) || (int_type<_Lhs> || int_type<_Rhs>);
+		(bit_type<_Lhs> && bit_type<_Rhs> && _Lhs::_Bit_Len == _Rhs::_Bit_Len) // prevent format
+		|| (int_type<_Lhs> && bit_type<_Rhs>)                                  //
+		|| (bit_type<_Lhs> && int_type<_Rhs>);
 
 template<typename _Tp, std::size_t _Len>
 concept bit_convertible =
diff --git a/include/cpu.h b/include/cpu.h
index 7d63df6..732d4b8 100644
--- a/include/cpu.h
+++ b/include/cpu.h
@@ -1,4 +1,6 @@
+#pragma once
 #include "module.h"
+#include <algorithm>
 #include <memory>
 #include <random>
 #include <vector>
@@ -7,7 +9,8 @@ namespace dark {
 
 class CPU {
 private:
-	std::vector<std::unique_ptr<ModuleBase>> modules;
+	std::vector<std::unique_ptr<ModuleBase>> mod_owned;
+	std::vector<ModuleBase *> modules;
 
 public:
 	unsigned long long cycles = 0;
@@ -19,9 +22,21 @@ private:
 	}
 
 public:
-	void add_module(std::unique_ptr<ModuleBase> module) {
-		modules.push_back(std::move(module));
+	/// @attention the pointer will be moved. you SHOULD NOT use it after calling this function.
+	template<typename _Tp>
+		requires std::derived_from<_Tp, ModuleBase>
+	void add_module(std::unique_ptr<_Tp> &module) {
+		modules.push_back(module.get());
+		mod_owned.emplace_back(std::move(module));
 	}
+	void add_module(std::unique_ptr<ModuleBase> module) {
+		modules.push_back(module.get());
+		mod_owned.emplace_back(std::move(module));
+	}
+	void add_module(ModuleBase *module) {
+		modules.push_back(module);
+	}
+
 	void run_once() {
 		++cycles;
 		for (auto &module: modules)
@@ -30,10 +45,7 @@ public:
 	}
 	void run_once_shuffle() {
 		static std::default_random_engine engine;
-		std::vector<ModuleBase *> shuffled;
-		shuffled.reserve(modules.size());
-		for (auto &module: modules)
-			shuffled.push_back(module.get());
+		std::vector<ModuleBase *> shuffled = modules;
 		std::shuffle(shuffled.begin(), shuffled.end(), engine);
 
 		++cycles;
diff --git a/include/module.h b/include/module.h
index a9a7a46..6ed7ea5 100644
--- a/include/module.h
+++ b/include/module.h
@@ -1,13 +1,21 @@
+#pragma once
 #include "synchronize.h"
 namespace dark {
 
+namespace details {
+	struct empty_class {
+		void sync() { /* do nothing */ }
+	};
+} // namespace details
+
 struct ModuleBase {
 	virtual void work() = 0;
 	virtual void sync() = 0;
 	virtual ~ModuleBase() = default;
 };
 
-template<typename _Tinput, typename _Toutput, typename _Tprivate>
+template<typename _Tinput, typename _Toutput, typename _Tprivate = details::empty_class>
+	requires std::is_aggregate_v<_Tinput> && std::is_aggregate_v<_Toutput> && std::is_aggregate_v<_Tprivate>
 struct Module : public ModuleBase, public _Tinput, public _Toutput, protected _Tprivate {
 	void sync() override final {
 		sync_member(static_cast<_Tinput &>(*this));
diff --git a/include/register.h b/include/register.h
index 136bf31..aa27df5 100644
--- a/include/register.h
+++ b/include/register.h
@@ -41,6 +41,7 @@ public:
 	}
 
 	explicit operator max_size_t() const { return this->_M_old; }
+	explicit operator bool() const { return this->_M_old; }
 };
 
 } // namespace dark
diff --git a/include/tools.h b/include/tools.h
index a757337..3c10d63 100644
--- a/include/tools.h
+++ b/include/tools.h
@@ -5,6 +5,8 @@
 #include "register.h"
 #include "synchronize.h"
 #include "wire.h"
+#include "module.h"
+#include "cpu.h"
 
 using dark::Bit;
 using dark::sign_extend;
diff --git a/include/wire.h b/include/wire.h
index 92dc7cc..5367df4 100644
--- a/include/wire.h
+++ b/include/wire.h
@@ -107,6 +107,10 @@ public:
 		this->_M_func.reset(_M_new_func(std::forward<_Fn>(fn)));
 		this->sync();
 	}
+
+	explicit operator bool() const {
+		return static_cast<max_size_t>(*this);
+	}
 };