From 109c7014ce805da2bdfbf3ae9fac50c08aad1e1c Mon Sep 17 00:00:00 2001
From: Minsoo Choo <minsoochoo0122@proton.me>
Date: Sun, 10 Mar 2024 20:04:25 -0400
Subject: [PATCH 01/24] Replace NULL with nullptr

Signed-off-by: Minsoo Choo <minsoochoo0122@proton.me>
---
 debug.cpp | 9 ++++-----
 state.cpp | 8 ++++----
 2 files changed, 8 insertions(+), 9 deletions(-)

diff --git a/debug.cpp b/debug.cpp
index e0a0b5e..ad87102 100644
--- a/debug.cpp
+++ b/debug.cpp
@@ -102,7 +102,7 @@ lutok::debug::event(void) const
 std::string
 lutok::debug::name(void) const
 {
-    assert(_pimpl->lua_debug.name != NULL);
+    assert(_pimpl->lua_debug.name != nullptr);
     return _pimpl->lua_debug.name;
 }
 
@@ -113,7 +113,7 @@ lutok::debug::name(void) const
 std::string
 lutok::debug::name_what(void) const
 {
-    assert(_pimpl->lua_debug.namewhat != NULL);
+    assert(_pimpl->lua_debug.namewhat != nullptr);
     return _pimpl->lua_debug.namewhat;
 }
 
@@ -124,7 +124,7 @@ lutok::debug::name_what(void) const
 std::string
 lutok::debug::what(void) const
 {
-    assert(_pimpl->lua_debug.what != NULL);
+    assert(_pimpl->lua_debug.what != nullptr);
     return _pimpl->lua_debug.what;
 }
 
@@ -135,7 +135,7 @@ lutok::debug::what(void) const
 std::string
 lutok::debug::source(void) const
 {
-    assert(_pimpl->lua_debug.source != NULL);
+    assert(_pimpl->lua_debug.source != nullptr);
     return _pimpl->lua_debug.source;
 }
 
@@ -187,6 +187,5 @@ lutok::debug::last_line_defined(void) const
 std::string
 lutok::debug::short_src(void) const
 {
-    assert(_pimpl->lua_debug.short_src != NULL);
     return _pimpl->lua_debug.short_src;
 }
diff --git a/state.cpp b/state.cpp
index 231f6e8..7092d44 100644
--- a/state.cpp
+++ b/state.cpp
@@ -242,7 +242,7 @@ struct lutok::state::impl {
 lutok::state::state(void)
 {
     lua_State* lua = luaL_newstate();
-    if (lua == NULL)
+    if (lua == nullptr)
         throw lutok::error("lua open failed");
     _pimpl.reset(new impl(lua, true));
 }
@@ -267,7 +267,7 @@ lutok::state::state(void* raw_state_) :
 /// code.
 lutok::state::~state(void)
 {
-    if (_pimpl->owned && _pimpl->lua_state != NULL)
+    if (_pimpl->owned && _pimpl->lua_state != nullptr)
         close();
 }
 
@@ -283,10 +283,10 @@ lutok::state::~state(void)
 void
 lutok::state::close(void)
 {
-    assert(_pimpl->lua_state != NULL);
+    assert(_pimpl->lua_state != nullptr);
     assert(lua_gettop(_pimpl->lua_state) == 0);
     lua_close(_pimpl->lua_state);
-    _pimpl->lua_state = NULL;
+    _pimpl->lua_state = nullptr;
 }
 
 

From 2ff507cbf4b4dbf36f7e3b22c58cba4e2116b055 Mon Sep 17 00:00:00 2001
From: Minsoo Choo <minsoochoo0122@proton.me>
Date: Sun, 10 Mar 2024 20:17:57 -0400
Subject: [PATCH 02/24] Use default destructors instead of empty ones

---
 c_gate.cpp     |  4 +---
 debug.cpp      |  4 +---
 exceptions.cpp | 12 +++---------
 3 files changed, 5 insertions(+), 15 deletions(-)

diff --git a/c_gate.cpp b/c_gate.cpp
index dde366e..b616f02 100644
--- a/c_gate.cpp
+++ b/c_gate.cpp
@@ -45,9 +45,7 @@ lutok::state_c_gate::state_c_gate(state& state_) :
 /// Destroying this object has no implications on the life cycle of the Lua
 /// state.  Only the corresponding state object controls when the Lua state is
 /// closed.
-lutok::state_c_gate::~state_c_gate(void)
-{
-}
+lutok::state_c_gate::~state_c_gate(void) = default;
 
 
 /// Creates a C++ state for a C Lua state.
diff --git a/debug.cpp b/debug.cpp
index ad87102..4a6304f 100644
--- a/debug.cpp
+++ b/debug.cpp
@@ -51,9 +51,7 @@ lutok::debug::debug(void) :
 
 
 /// Destructor.
-lutok::debug::~debug(void)
-{
-}
+lutok::debug::~debug(void) = default;
 
 
 /// Wrapper around lua_getinfo.
diff --git a/exceptions.cpp b/exceptions.cpp
index 2b1c968..a9c593b 100644
--- a/exceptions.cpp
+++ b/exceptions.cpp
@@ -45,9 +45,7 @@ lutok::error::error(const std::string& message) :
 
 
 /// Destructor for the error.
-lutok::error::~error(void) throw()
-{
-}
+lutok::error::~error(void) throw() = default;
 
 
 /// Constructs a new error.
@@ -63,9 +61,7 @@ lutok::api_error::api_error(const std::string& api_function_,
 
 
 /// Destructor for the error.
-lutok::api_error::~api_error(void) throw()
-{
-}
+lutok::api_error::~api_error(void) throw() = default;
 
 
 /// Constructs a new api_error with the message on the top of the Lua stack.
@@ -111,9 +107,7 @@ lutok::file_not_found_error::file_not_found_error(
 
 
 /// Destructor for the error.
-lutok::file_not_found_error::~file_not_found_error(void) throw()
-{
-}
+lutok::file_not_found_error::~file_not_found_error(void) throw() = default;
 
 
 /// Gets the name of the file that could not be found.

From 88a23e6de4fc8f0b076b7e81224aeec8f8e83267 Mon Sep 17 00:00:00 2001
From: Minsoo Choo <minsoochoo0122@proton.me>
Date: Sun, 10 Mar 2024 20:25:20 -0400
Subject: [PATCH 03/24] Add include guard

---
 include/lutok/c_gate.hpp     | 5 +++++
 include/lutok/debug.hpp      | 5 +++++
 include/lutok/exceptions.hpp | 5 +++++
 include/lutok/state.hpp      | 5 +++++
 include/lutok/state.ipp      | 5 +++++
 5 files changed, 25 insertions(+)

diff --git a/include/lutok/c_gate.hpp b/include/lutok/c_gate.hpp
index 4fabe16..14a359a 100644
--- a/include/lutok/c_gate.hpp
+++ b/include/lutok/c_gate.hpp
@@ -1 +1,6 @@
+#ifndef C_GATE_HPP
+#define C_GATE_HPP
+
 #include "../../c_gate.hpp"
+
+#endif // C_GATE_HPP
\ No newline at end of file
diff --git a/include/lutok/debug.hpp b/include/lutok/debug.hpp
index b942bbd..8031eeb 100644
--- a/include/lutok/debug.hpp
+++ b/include/lutok/debug.hpp
@@ -1 +1,6 @@
+#ifndef DEBUG_HPP
+#define DEBUG_HPP
+
 #include "../../debug.hpp"
+
+#endif // DEBUG_HPP
\ No newline at end of file
diff --git a/include/lutok/exceptions.hpp b/include/lutok/exceptions.hpp
index 97f49a1..0e4e3ab 100644
--- a/include/lutok/exceptions.hpp
+++ b/include/lutok/exceptions.hpp
@@ -1 +1,6 @@
+#ifndef EXCEPTIONS_HPP
+#define EXCEPTIONS_HPP
+
 #include "../../exceptions.hpp"
+
+#endif // EXCEPTIONS_HPP
\ No newline at end of file
diff --git a/include/lutok/state.hpp b/include/lutok/state.hpp
index 48ac65c..f7c85cd 100644
--- a/include/lutok/state.hpp
+++ b/include/lutok/state.hpp
@@ -1 +1,6 @@
+#ifndef STATE_HPP
+#define STATE_HPP
+
 #include "../../state.hpp"
+
+#endif // STATE_HPP
\ No newline at end of file
diff --git a/include/lutok/state.ipp b/include/lutok/state.ipp
index 531d9c1..8d4cc19 100644
--- a/include/lutok/state.ipp
+++ b/include/lutok/state.ipp
@@ -1 +1,6 @@
+#ifndef STATE_IPP
+#define STATE_IPP
+
 #include "../../state.ipp"
+
+#endif // STATE_IPP
\ No newline at end of file

From ee54feb8da56cc42e3aa30967f44abe4104fffc8 Mon Sep 17 00:00:00 2001
From: Minsoo Choo <minsoochoo0122@proton.me>
Date: Sun, 10 Mar 2024 20:31:23 -0400
Subject: [PATCH 04/24] Make member function const if possible

---
 c_gate.cpp        |  2 +-
 c_gate.hpp        |  2 +-
 debug.cpp         |  4 +--
 debug.hpp         |  4 +--
 stack_cleaner.cpp |  2 +-
 stack_cleaner.hpp |  2 +-
 state.cpp         | 68 ++++++++++++++++++++++-----------------------
 state.hpp         | 70 +++++++++++++++++++++++------------------------
 8 files changed, 77 insertions(+), 77 deletions(-)

diff --git a/c_gate.cpp b/c_gate.cpp
index b616f02..7de7ad3 100644
--- a/c_gate.cpp
+++ b/c_gate.cpp
@@ -68,7 +68,7 @@ lutok::state_c_gate::connect(lua_State* raw_state)
 ///
 /// \return A native lua_State object holding the Lua C API state.
 lua_State*
-lutok::state_c_gate::c_state(void)
+lutok::state_c_gate::c_state(void) const
 {
     return static_cast< lua_State* >(_state.raw_state());
 }
diff --git a/c_gate.hpp b/c_gate.hpp
index 36bc9c2..6415bcd 100644
--- a/c_gate.hpp
+++ b/c_gate.hpp
@@ -62,7 +62,7 @@ class state_c_gate {
 
     static state connect(lua_State*);
 
-    lua_State* c_state(void);
+    lua_State* c_state(void) const;
 };
 
 
diff --git a/debug.cpp b/debug.cpp
index 4a6304f..ff7ec04 100644
--- a/debug.cpp
+++ b/debug.cpp
@@ -62,7 +62,7 @@ lutok::debug::~debug(void) = default;
 /// \warning Terminates execution if there is not enough memory to manipulate
 /// the Lua stack.
 void
-lutok::debug::get_info(state& s, const std::string& what_)
+lutok::debug::get_info(state& s, const std::string& what_) const
 {
     lua_State* raw_state = state_c_gate(s).c_state();
 
@@ -76,7 +76,7 @@ lutok::debug::get_info(state& s, const std::string& what_)
 /// \param s The Lua state.
 /// \param level The second parameter to lua_getstack.
 void
-lutok::debug::get_stack(state& s, const int level)
+lutok::debug::get_stack(state& s, const int level) const
 {
     lua_State* raw_state = state_c_gate(s).c_state();
 
diff --git a/debug.hpp b/debug.hpp
index 6ada1fc..0ec6236 100644
--- a/debug.hpp
+++ b/debug.hpp
@@ -61,8 +61,8 @@ class debug {
     debug(void);
     ~debug(void);
 
-    void get_info(state&, const std::string&);
-    void get_stack(state&, const int);
+    void get_info(state&, const std::string&) const;
+    void get_stack(state&, const int) const;
 
     int event(void) const;
     std::string name(void) const;
diff --git a/stack_cleaner.cpp b/stack_cleaner.cpp
index 419e55a..ccbeb1e 100644
--- a/stack_cleaner.cpp
+++ b/stack_cleaner.cpp
@@ -85,7 +85,7 @@ lutok::stack_cleaner::~stack_cleaner(void)
 /// elements that are currently in the stack will not be touched during
 /// destruction when the function is called.
 void
-lutok::stack_cleaner::forget(void)
+lutok::stack_cleaner::forget(void) const
 {
     _pimpl->original_depth = _pimpl->state_ref.get_top();
 }
diff --git a/stack_cleaner.hpp b/stack_cleaner.hpp
index 3e3a8ed..e0b62fa 100644
--- a/stack_cleaner.hpp
+++ b/stack_cleaner.hpp
@@ -84,7 +84,7 @@ class stack_cleaner {
     stack_cleaner(state&);
     ~stack_cleaner(void);
 
-    void forget(void);
+    void forget(void) const;
 };
 
 
diff --git a/state.cpp b/state.cpp
index 7092d44..46ad32f 100644
--- a/state.cpp
+++ b/state.cpp
@@ -281,7 +281,7 @@ lutok::state::~state(void)
 /// \pre The Lua stack is empty.  This is not truly necessary but ensures that
 ///     our code is consistent and clears the stack explicitly.
 void
-lutok::state::close(void)
+lutok::state::close(void) const
 {
     assert(_pimpl->lua_state != nullptr);
     assert(lua_gettop(_pimpl->lua_state) == 0);
@@ -315,7 +315,7 @@ lutok::state::get_global(const std::string& name)
 ///
 /// \post state(-1) Contains the reference to the globals table.
 void
-lutok::state::get_global_table(void)
+lutok::state::get_global_table(void) const
 {
 #if LUA_VERSION_NUM >= 502
     lua_pushvalue(_pimpl->lua_state, registry_index);
@@ -338,7 +338,7 @@ lutok::state::get_global_table(void)
 /// \warning Terminates execution if there is not enough memory to manipulate
 /// the Lua stack.
 bool
-lutok::state::get_metafield(const int index, const std::string& name)
+lutok::state::get_metafield(const int index, const std::string& name) const
 {
     return luaL_getmetafield(_pimpl->lua_state, index, name.c_str()) != 0;
 }
@@ -350,7 +350,7 @@ lutok::state::get_metafield(const int index, const std::string& name)
 ///
 /// \return The return value of lua_getmetatable.
 bool
-lutok::state::get_metatable(const int index)
+lutok::state::get_metatable(const int index) const
 {
     return lua_getmetatable(_pimpl->lua_state, index) != 0;
 }
@@ -381,7 +381,7 @@ lutok::state::get_table(const int index)
 ///
 /// \return The return value of lua_gettop.
 int
-lutok::state::get_top(void)
+lutok::state::get_top(void) const
 {
     return lua_gettop(_pimpl->lua_state);
 }
@@ -391,7 +391,7 @@ lutok::state::get_top(void)
 ///
 /// \param index The second parameter to lua_insert.
 void
-lutok::state::insert(const int index)
+lutok::state::insert(const int index) const
 {
     lua_insert(_pimpl->lua_state, index);
 }
@@ -403,7 +403,7 @@ lutok::state::insert(const int index)
 ///
 /// \return The return value of lua_isboolean.
 bool
-lutok::state::is_boolean(const int index)
+lutok::state::is_boolean(const int index) const
 {
     return lua_isboolean(_pimpl->lua_state, index);
 }
@@ -415,7 +415,7 @@ lutok::state::is_boolean(const int index)
 ///
 /// \return The return value of lua_isfunction.
 bool
-lutok::state::is_function(const int index)
+lutok::state::is_function(const int index) const
 {
     return lua_isfunction(_pimpl->lua_state, index);
 }
@@ -427,7 +427,7 @@ lutok::state::is_function(const int index)
 ///
 /// \return The return value of lua_isnil.
 bool
-lutok::state::is_nil(const int index)
+lutok::state::is_nil(const int index) const
 {
     return lua_isnil(_pimpl->lua_state, index);
 }
@@ -439,7 +439,7 @@ lutok::state::is_nil(const int index)
 ///
 /// \return The return value of lua_isnumber.
 bool
-lutok::state::is_number(const int index)
+lutok::state::is_number(const int index) const
 {
     return lua_isnumber(_pimpl->lua_state, index);
 }
@@ -451,7 +451,7 @@ lutok::state::is_number(const int index)
 ///
 /// \return The return value of lua_isstring.
 bool
-lutok::state::is_string(const int index)
+lutok::state::is_string(const int index) const
 {
     return lua_isstring(_pimpl->lua_state, index);
 }
@@ -463,7 +463,7 @@ lutok::state::is_string(const int index)
 ///
 /// \return The return value of lua_istable.
 bool
-lutok::state::is_table(const int index)
+lutok::state::is_table(const int index) const
 {
     return lua_istable(_pimpl->lua_state, index);
 }
@@ -475,7 +475,7 @@ lutok::state::is_table(const int index)
 ///
 /// \return The return value of lua_isuserdata.
 bool
-lutok::state::is_userdata(const int index)
+lutok::state::is_userdata(const int index) const
 {
     return lua_isuserdata(_pimpl->lua_state, index);
 }
@@ -518,7 +518,7 @@ lutok::state::load_string(const std::string& str)
 ///
 /// \warning Terminates execution if there is not enough memory.
 void
-lutok::state::new_table(void)
+lutok::state::new_table(void) const
 {
     lua_newtable(_pimpl->lua_state);
 }
@@ -535,7 +535,7 @@ lutok::state::new_table(void)
 ///
 /// \warning Terminates execution if there is not enough memory.
 void*
-lutok::state::new_userdata_voidp(const size_t size)
+lutok::state::new_userdata_voidp(const size_t size) const
 {
     return lua_newuserdata(_pimpl->lua_state, size);
 }
@@ -574,7 +574,7 @@ lutok::state::next(const int index)
 ///
 /// \warning Terminates execution if there is not enough memory.
 void
-lutok::state::open_all(void)
+lutok::state::open_all(void) const
 {
     luaL_openlibs(_pimpl->lua_state);
 }
@@ -600,7 +600,7 @@ lutok::state::open_base(void)
 ///
 /// \warning Terminates execution if there is not enough memory.
 void
-lutok::state::open_string(void)
+lutok::state::open_string(void) const
 {
 #if LUA_VERSION_NUM >= 502
     luaL_requiref(_pimpl->lua_state, LUA_STRLIBNAME, luaopen_string, 1);
@@ -619,7 +619,7 @@ lutok::state::open_string(void)
 ///
 /// \warning Terminates execution if there is not enough memory.
 void
-lutok::state::open_table(void)
+lutok::state::open_table(void) const
 {
 #if LUA_VERSION_NUM >= 502
     luaL_requiref(_pimpl->lua_state, LUA_TABLIBNAME, luaopen_table, 1);
@@ -651,7 +651,7 @@ lutok::state::pcall(const int nargs, const int nresults, const int errfunc)
 ///
 /// \param count The second parameter to lua_pop.
 void
-lutok::state::pop(const int count)
+lutok::state::pop(const int count) const
 {
     assert(count <= lua_gettop(_pimpl->lua_state));
     lua_pop(_pimpl->lua_state, count);
@@ -663,7 +663,7 @@ lutok::state::pop(const int count)
 ///
 /// \param value The second parameter to lua_pushboolean.
 void
-lutok::state::push_boolean(const bool value)
+lutok::state::push_boolean(const bool value) const
 {
     lua_pushboolean(_pimpl->lua_state, value ? 1 : 0);
 }
@@ -677,7 +677,7 @@ lutok::state::push_boolean(const bool value)
 /// \param function The C++ function to be pushed as a closure.
 /// \param nvalues The number of upvalues that the function receives.
 void
-lutok::state::push_cxx_closure(cxx_function function, const int nvalues)
+lutok::state::push_cxx_closure(cxx_function function, const int nvalues) const
 {
     cxx_function *data = static_cast< cxx_function* >(
         lua_newuserdata(_pimpl->lua_state, sizeof(cxx_function)));
@@ -693,7 +693,7 @@ lutok::state::push_cxx_closure(cxx_function function, const int nvalues)
 ///
 /// \param function The C++ function to be pushed.
 void
-lutok::state::push_cxx_function(cxx_function function)
+lutok::state::push_cxx_function(cxx_function function) const
 {
     cxx_function *data = static_cast< cxx_function* >(
         lua_newuserdata(_pimpl->lua_state, sizeof(cxx_function)));
@@ -706,7 +706,7 @@ lutok::state::push_cxx_function(cxx_function function)
 ///
 /// \param value The second parameter to lua_pushinteger.
 void
-lutok::state::push_integer(const int value)
+lutok::state::push_integer(const int value) const
 {
     lua_pushinteger(_pimpl->lua_state, value);
 }
@@ -714,7 +714,7 @@ lutok::state::push_integer(const int value)
 
 /// Wrapper around lua_pushnil.
 void
-lutok::state::push_nil(void)
+lutok::state::push_nil(void) const
 {
     lua_pushnil(_pimpl->lua_state);
 }
@@ -726,7 +726,7 @@ lutok::state::push_nil(void)
 ///
 /// \warning Terminates execution if there is not enough memory.
 void
-lutok::state::push_string(const std::string& str)
+lutok::state::push_string(const std::string& str) const
 {
     lua_pushstring(_pimpl->lua_state, str.c_str());
 }
@@ -736,7 +736,7 @@ lutok::state::push_string(const std::string& str)
 ///
 /// \param index The second parameter to lua_pushvalue.
 void
-lutok::state::push_value(const int index)
+lutok::state::push_value(const int index) const
 {
     lua_pushvalue(_pimpl->lua_state, index);
 }
@@ -746,7 +746,7 @@ lutok::state::push_value(const int index)
 ///
 /// \param index The second parameter to lua_rawget.
 void
-lutok::state::raw_get(const int index)
+lutok::state::raw_get(const int index) const
 {
     lua_rawget(_pimpl->lua_state, index);
 }
@@ -759,7 +759,7 @@ lutok::state::raw_get(const int index)
 /// \warning Terminates execution if there is not enough memory to manipulate
 /// the Lua stack.
 void
-lutok::state::raw_set(const int index)
+lutok::state::raw_set(const int index) const
 {
     lua_rawset(_pimpl->lua_state, index);
 }
@@ -789,7 +789,7 @@ lutok::state::set_global(const std::string& name)
 ///
 /// \param index The second parameter to lua_setmetatable.
 void
-lutok::state::set_metatable(const int index)
+lutok::state::set_metatable(const int index) const
 {
     lua_setmetatable(_pimpl->lua_state, index);
 }
@@ -822,7 +822,7 @@ lutok::state::set_table(const int index)
 ///
 /// \return The return value of lua_toboolean.
 bool
-lutok::state::to_boolean(const int index)
+lutok::state::to_boolean(const int index) const
 {
     assert(is_boolean(index));
     return lua_toboolean(_pimpl->lua_state, index);
@@ -835,7 +835,7 @@ lutok::state::to_boolean(const int index)
 ///
 /// \return The return value of lua_tointeger.
 long
-lutok::state::to_integer(const int index)
+lutok::state::to_integer(const int index) const
 {
     assert(is_number(index));
     return lua_tointeger(_pimpl->lua_state, index);
@@ -853,7 +853,7 @@ lutok::state::to_integer(const int index)
 ///
 /// \warning Terminates execution if there is not enough memory.
 void*
-lutok::state::to_userdata_voidp(const int index)
+lutok::state::to_userdata_voidp(const int index) const
 {
     return lua_touserdata(_pimpl->lua_state, index);
 }
@@ -868,7 +868,7 @@ lutok::state::to_userdata_voidp(const int index)
 ///
 /// \warning Terminates execution if there is not enough memory.
 std::string
-lutok::state::to_string(const int index)
+lutok::state::to_string(const int index) const
 {
     assert(is_string(index));
     const char *raw_string = lua_tostring(_pimpl->lua_state, index);
@@ -898,7 +898,7 @@ lutok::state::upvalue_index(const int index)
 /// to call this method is by using the c_gate module, and c_gate takes care of
 /// casting this object to the appropriate type.
 void*
-lutok::state::raw_state(void)
+lutok::state::raw_state(void) const
 {
     return _pimpl->lua_state;
 }
diff --git a/state.hpp b/state.hpp
index 3b088f1..dc933b5 100644
--- a/state.hpp
+++ b/state.hpp
@@ -74,60 +74,60 @@ class state {
     /// Pointer to the shared internal implementation.
     std::shared_ptr< impl > _pimpl;
 
-    void* new_userdata_voidp(const size_t);
-    void* to_userdata_voidp(const int);
+    void* new_userdata_voidp(const size_t) const;
+    void* to_userdata_voidp(const int) const;
 
     friend class state_c_gate;
     explicit state(void*);
-    void* raw_state(void);
+    void* raw_state(void) const;
 
 public:
     state(void);
     ~state(void);
 
-    void close(void);
+    void close(void) const;
     void get_global(const std::string&);
-    void get_global_table(void);
-    bool get_metafield(const int, const std::string&);
-    bool get_metatable(const int);
+    void get_global_table(void) const;
+    bool get_metafield(const int, const std::string&) const;
+    bool get_metatable(const int) const;
     void get_table(const int);
-    int get_top(void);
-    void insert(const int);
-    bool is_boolean(const int);
-    bool is_function(const int);
-    bool is_nil(const int);
-    bool is_number(const int);
-    bool is_string(const int);
-    bool is_table(const int);
-    bool is_userdata(const int);
+    int get_top(void) const;
+    void insert(const int) const;
+    bool is_boolean(const int) const;
+    bool is_function(const int) const;
+    bool is_nil(const int) const;
+    bool is_number(const int) const;
+    bool is_string(const int) const;
+    bool is_table(const int) const;
+    bool is_userdata(const int) const;
     void load_file(const std::string&);
     void load_string(const std::string&);
-    void new_table(void);
+    void new_table(void) const;
     template< typename Type > Type* new_userdata(void);
     bool next(const int);
-    void open_all(void);
+    void open_all(void) const;
     void open_base(void);
-    void open_string(void);
-    void open_table(void);
+    void open_string(void) const;
+    void open_table(void) const;
     void pcall(const int, const int, const int);
-    void pop(const int);
-    void push_boolean(const bool);
-    void push_cxx_closure(cxx_function, const int);
-    void push_cxx_function(cxx_function);
-    void push_integer(const int);
-    void push_nil(void);
-    void push_string(const std::string&);
-    void push_value(const int);
-    void raw_get(const int);
-    void raw_set(const int);
+    void pop(const int) const;
+    void push_boolean(const bool) const;
+    void push_cxx_closure(cxx_function, const int) const;
+    void push_cxx_function(cxx_function) const;
+    void push_integer(const int) const;
+    void push_nil(void) const;
+    void push_string(const std::string&) const;
+    void push_value(const int) const;
+    void raw_get(const int) const;
+    void raw_set(const int) const;
     void set_global(const std::string&);
-    void set_metatable(const int);
+    void set_metatable(const int) const;
     void set_table(const int);
-    bool to_boolean(const int);
-    long to_integer(const int);
+    bool to_boolean(const int) const;
+    long to_integer(const int) const;
     template< typename Type > Type* to_userdata(const int);
-    std::string to_string(const int);
-    int upvalue_index(const int);
+    std::string to_string(const int) const;
+    static int upvalue_index(const int);
 };
 
 

From 03146c81383f3d68d9281b1156d5bb27151f87e0 Mon Sep 17 00:00:00 2001
From: Minsoo Choo <minsoochoo0122@proton.me>
Date: Sun, 10 Mar 2024 20:34:41 -0400
Subject: [PATCH 05/24] Replace throw with noexcept

---
 exceptions.cpp | 6 +++---
 exceptions.hpp | 6 +++---
 state.cpp      | 2 +-
 3 files changed, 7 insertions(+), 7 deletions(-)

diff --git a/exceptions.cpp b/exceptions.cpp
index a9c593b..f18aa39 100644
--- a/exceptions.cpp
+++ b/exceptions.cpp
@@ -45,7 +45,7 @@ lutok::error::error(const std::string& message) :
 
 
 /// Destructor for the error.
-lutok::error::~error(void) throw() = default;
+lutok::error::~error(void) noexcept = default;
 
 
 /// Constructs a new error.
@@ -61,7 +61,7 @@ lutok::api_error::api_error(const std::string& api_function_,
 
 
 /// Destructor for the error.
-lutok::api_error::~api_error(void) throw() = default;
+lutok::api_error::~api_error(void) noexcept = default;
 
 
 /// Constructs a new api_error with the message on the top of the Lua stack.
@@ -107,7 +107,7 @@ lutok::file_not_found_error::file_not_found_error(
 
 
 /// Destructor for the error.
-lutok::file_not_found_error::~file_not_found_error(void) throw() = default;
+lutok::file_not_found_error::~file_not_found_error(void) noexcept = default;
 
 
 /// Gets the name of the file that could not be found.
diff --git a/exceptions.hpp b/exceptions.hpp
index 93a7948..91fc0df 100644
--- a/exceptions.hpp
+++ b/exceptions.hpp
@@ -45,7 +45,7 @@ class state;
 class error : public std::runtime_error {
 public:
     explicit error(const std::string&);
-    virtual ~error(void) throw();
+    virtual ~error(void) noexcept;
 };
 
 
@@ -56,7 +56,7 @@ class api_error : public error {
 
 public:
     explicit api_error(const std::string&, const std::string&);
-    virtual ~api_error(void) throw();
+    virtual ~api_error(void) noexcept;
 
     static api_error from_stack(state&, const std::string&);
 
@@ -71,7 +71,7 @@ class file_not_found_error : public error {
 
 public:
     explicit file_not_found_error(const std::string&);
-    virtual ~file_not_found_error(void) throw();
+    virtual ~file_not_found_error(void) noexcept;
 
     const std::string& filename(void) const;
 };
diff --git a/state.cpp b/state.cpp
index 46ad32f..44e56b1 100644
--- a/state.cpp
+++ b/state.cpp
@@ -137,7 +137,7 @@ protected_settable(lua_State* state)
 /// function.
 static int
 call_cxx_function_from_c(lutok::cxx_function function,
-                         lua_State* raw_state) throw()
+                         lua_State* raw_state) noexcept
 {
     char error_buf[1024];
 

From cbf4e05d5d35f907997a179f28c42fe072136624 Mon Sep 17 00:00:00 2001
From: Minsoo Choo <minsoochoo0122@proton.me>
Date: Sun, 10 Mar 2024 20:41:14 -0400
Subject: [PATCH 06/24] Mark single-argument constructors explicit

This avoids unintentional implicit conversions.
---
 c_gate.hpp        | 2 +-
 stack_cleaner.hpp | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/c_gate.hpp b/c_gate.hpp
index 6415bcd..f98e276 100644
--- a/c_gate.hpp
+++ b/c_gate.hpp
@@ -57,7 +57,7 @@ class state_c_gate {
     state& _state;
 
 public:
-    state_c_gate(state&);
+    explicit state_c_gate(state&);
     ~state_c_gate(void);
 
     static state connect(lua_State*);
diff --git a/stack_cleaner.hpp b/stack_cleaner.hpp
index e0b62fa..bb0ea49 100644
--- a/stack_cleaner.hpp
+++ b/stack_cleaner.hpp
@@ -81,7 +81,7 @@ class stack_cleaner {
     stack_cleaner& operator=(const stack_cleaner&);
 
 public:
-    stack_cleaner(state&);
+    explicit stack_cleaner(state&);
     ~stack_cleaner(void);
 
     void forget(void) const;

From 7a5b4afffb4eb0f6c4b093bc01b7559997802fb2 Mon Sep 17 00:00:00 2001
From: Minsoo Choo <minsoochoo0122@proton.me>
Date: Sun, 10 Mar 2024 20:44:57 -0400
Subject: [PATCH 07/24] Remove const-qualified parameters in the function
 declaration

Const-qualification of parameters only has an effect in function
definitions.
---
 debug.hpp      |  2 +-
 operations.hpp | 10 ++++-----
 state.hpp      | 58 +++++++++++++++++++++++++-------------------------
 3 files changed, 35 insertions(+), 35 deletions(-)

diff --git a/debug.hpp b/debug.hpp
index 0ec6236..a810ae5 100644
--- a/debug.hpp
+++ b/debug.hpp
@@ -62,7 +62,7 @@ class debug {
     ~debug(void);
 
     void get_info(state&, const std::string&) const;
-    void get_stack(state&, const int) const;
+    void get_stack(state&, int) const;
 
     int event(void) const;
     std::string name(void) const;
diff --git a/operations.hpp b/operations.hpp
index ead7c77..c6a5296 100644
--- a/operations.hpp
+++ b/operations.hpp
@@ -43,11 +43,11 @@ namespace lutok {
 
 void create_module(state&, const std::string&,
                    const std::map< std::string, cxx_function >&);
-unsigned int do_file(state&, const std::string&, const int, const int,
-                     const int);
-unsigned int do_string(state&, const std::string&, const int, const int,
-                       const int);
-void eval(state&, const std::string&, const int);
+unsigned int do_file(state&, const std::string&, int, int,
+                     int);
+unsigned int do_string(state&, const std::string&, int, int,
+                       int);
+void eval(state&, const std::string&, int);
 
 
 }  // namespace lutok
diff --git a/state.hpp b/state.hpp
index dc933b5..a9d8776 100644
--- a/state.hpp
+++ b/state.hpp
@@ -74,8 +74,8 @@ class state {
     /// Pointer to the shared internal implementation.
     std::shared_ptr< impl > _pimpl;
 
-    void* new_userdata_voidp(const size_t) const;
-    void* to_userdata_voidp(const int) const;
+    void* new_userdata_voidp(size_t) const;
+    void* to_userdata_voidp(int) const;
 
     friend class state_c_gate;
     explicit state(void*);
@@ -88,46 +88,46 @@ class state {
     void close(void) const;
     void get_global(const std::string&);
     void get_global_table(void) const;
-    bool get_metafield(const int, const std::string&) const;
-    bool get_metatable(const int) const;
-    void get_table(const int);
+    bool get_metafield(int, const std::string&) const;
+    bool get_metatable(int) const;
+    void get_table(int);
     int get_top(void) const;
-    void insert(const int) const;
-    bool is_boolean(const int) const;
-    bool is_function(const int) const;
-    bool is_nil(const int) const;
-    bool is_number(const int) const;
-    bool is_string(const int) const;
-    bool is_table(const int) const;
-    bool is_userdata(const int) const;
+    void insert(int) const;
+    bool is_boolean(int) const;
+    bool is_function(int) const;
+    bool is_nil(int) const;
+    bool is_number(int) const;
+    bool is_string(int) const;
+    bool is_table(int) const;
+    bool is_userdata(int) const;
     void load_file(const std::string&);
     void load_string(const std::string&);
     void new_table(void) const;
     template< typename Type > Type* new_userdata(void);
-    bool next(const int);
+    bool next(int);
     void open_all(void) const;
     void open_base(void);
     void open_string(void) const;
     void open_table(void) const;
-    void pcall(const int, const int, const int);
-    void pop(const int) const;
-    void push_boolean(const bool) const;
-    void push_cxx_closure(cxx_function, const int) const;
+    void pcall(int, int, int);
+    void pop(int) const;
+    void push_boolean(bool) const;
+    void push_cxx_closure(cxx_function, int) const;
     void push_cxx_function(cxx_function) const;
-    void push_integer(const int) const;
+    void push_integer(int) const;
     void push_nil(void) const;
     void push_string(const std::string&) const;
-    void push_value(const int) const;
-    void raw_get(const int) const;
-    void raw_set(const int) const;
+    void push_value(int) const;
+    void raw_get(int) const;
+    void raw_set(int) const;
     void set_global(const std::string&);
-    void set_metatable(const int) const;
-    void set_table(const int);
-    bool to_boolean(const int) const;
-    long to_integer(const int) const;
-    template< typename Type > Type* to_userdata(const int);
-    std::string to_string(const int) const;
-    static int upvalue_index(const int);
+    void set_metatable(int) const;
+    void set_table(int);
+    bool to_boolean(int) const;
+    long to_integer(int) const;
+    template< typename Type > Type* to_userdata(int);
+    std::string to_string(int) const;
+    static int upvalue_index(int);
 };
 
 

From 38f24885cd261964af3487ec4a54e7075801a109 Mon Sep 17 00:00:00 2001
From: Minsoo Choo <minsoochoo0122@proton.me>
Date: Sun, 10 Mar 2024 20:47:23 -0400
Subject: [PATCH 08/24] Prefer using 'override' instead of 'virtual'

---
 exceptions.hpp | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/exceptions.hpp b/exceptions.hpp
index 91fc0df..ab90514 100644
--- a/exceptions.hpp
+++ b/exceptions.hpp
@@ -45,7 +45,7 @@ class state;
 class error : public std::runtime_error {
 public:
     explicit error(const std::string&);
-    virtual ~error(void) noexcept;
+    ~error(void) noexcept override;
 };
 
 
@@ -56,7 +56,7 @@ class api_error : public error {
 
 public:
     explicit api_error(const std::string&, const std::string&);
-    virtual ~api_error(void) noexcept;
+    ~api_error(void) noexcept override;
 
     static api_error from_stack(state&, const std::string&);
 
@@ -71,7 +71,7 @@ class file_not_found_error : public error {
 
 public:
     explicit file_not_found_error(const std::string&);
-    virtual ~file_not_found_error(void) noexcept;
+    ~file_not_found_error(void) noexcept override;
 
     const std::string& filename(void) const;
 };

From d15b98ad97fff6611b4cc3eada1d0afa800da946 Mon Sep 17 00:00:00 2001
From: Minsoo Choo <minsoochoo0122@proton.me>
Date: Sun, 10 Mar 2024 20:51:13 -0400
Subject: [PATCH 09/24] Use range-based loops

---
 operations.cpp | 7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)

diff --git a/operations.cpp b/operations.cpp
index 1b70dc4..12493ae 100644
--- a/operations.cpp
+++ b/operations.cpp
@@ -47,10 +47,9 @@ lutok::create_module(state& s, const std::string& name,
 {
     stack_cleaner cleaner(s);
     s.new_table();
-    for (std::map< std::string, cxx_function >::const_iterator
-         iter = members.begin(); iter != members.end(); iter++) {
-        s.push_string((*iter).first);
-        s.push_cxx_function((*iter).second);
+    for (const auto & member : members) {
+        s.push_string(member.first);
+        s.push_cxx_function(member.second);
         s.set_table(-3);
     }
     s.set_global(name);

From c582111941b3e7d4462ff8f924a457b16ad651aa Mon Sep 17 00:00:00 2001
From: Minsoo Choo <minsoochoo0122@proton.me>
Date: Sun, 10 Mar 2024 20:54:53 -0400
Subject: [PATCH 10/24] Use static_cast to avoid implicit conversion

---
 stack_cleaner.cpp | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/stack_cleaner.cpp b/stack_cleaner.cpp
index ccbeb1e..ef546d2 100644
--- a/stack_cleaner.cpp
+++ b/stack_cleaner.cpp
@@ -75,7 +75,7 @@ lutok::stack_cleaner::~stack_cleaner(void)
     assert(current_depth >= _pimpl->original_depth);
     const unsigned int diff = current_depth - _pimpl->original_depth;
     if (diff > 0)
-        _pimpl->state_ref.pop(diff);
+        _pimpl->state_ref.pop(static_cast<int>(diff));
 }
 
 

From 664a031d4904e9664178be974c81b8cb58084bf2 Mon Sep 17 00:00:00 2001
From: Minsoo Choo <minsoochoo0122@proton.me>
Date: Sun, 10 Mar 2024 20:56:11 -0400
Subject: [PATCH 11/24] Use a braced initializer list for return type

Repeating the return type from the declaration should be avoided.
---
 state.cpp | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/state.cpp b/state.cpp
index 44e56b1..9ad4e6c 100644
--- a/state.cpp
+++ b/state.cpp
@@ -875,7 +875,7 @@ lutok::state::to_string(const int index) const
     // Note that the creation of a string object below (explicit for clarity)
     // implies that the raw string is duplicated and, henceforth, the string is
     // safe even if the corresponding element is popped from the Lua stack.
-    return std::string(raw_string);
+    return {raw_string};
 }
 
 

From 412bbe474d6bd08dd3b3cf3adf75aad8bb43af7d Mon Sep 17 00:00:00 2001
From: Minsoo Choo <minsoochoo0122@proton.me>
Date: Sun, 10 Mar 2024 20:57:43 -0400
Subject: [PATCH 12/24] Use auto when initializing with a cast

This helps avoiding duplicating the type name.
---
 state.cpp | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/state.cpp b/state.cpp
index 9ad4e6c..1ea8309 100644
--- a/state.cpp
+++ b/state.cpp
@@ -183,7 +183,7 @@ cxx_closure_trampoline(lua_State* raw_state)
         nupvalues = debug.nups;
     }
 
-    lutok::cxx_function* function = state.to_userdata< lutok::cxx_function >(
+    auto* function = state.to_userdata< lutok::cxx_function >(
         state.upvalue_index(nupvalues));
     return call_cxx_function_from_c(*function, raw_state);
 }
@@ -203,7 +203,7 @@ static int
 cxx_function_trampoline(lua_State* raw_state)
 {
     lutok::state state = lutok::state_c_gate::connect(raw_state);
-    lutok::cxx_function* function = state.to_userdata< lutok::cxx_function >(
+    auto* function = state.to_userdata< lutok::cxx_function >(
         state.upvalue_index(1));
     return call_cxx_function_from_c(*function, raw_state);
 }
@@ -679,7 +679,7 @@ lutok::state::push_boolean(const bool value) const
 void
 lutok::state::push_cxx_closure(cxx_function function, const int nvalues) const
 {
-    cxx_function *data = static_cast< cxx_function* >(
+    auto *data = static_cast< cxx_function* >(
         lua_newuserdata(_pimpl->lua_state, sizeof(cxx_function)));
     *data = function;
     lua_pushcclosure(_pimpl->lua_state, cxx_closure_trampoline, nvalues + 1);
@@ -695,7 +695,7 @@ lutok::state::push_cxx_closure(cxx_function function, const int nvalues) const
 void
 lutok::state::push_cxx_function(cxx_function function) const
 {
-    cxx_function *data = static_cast< cxx_function* >(
+    auto *data = static_cast< cxx_function* >(
         lua_newuserdata(_pimpl->lua_state, sizeof(cxx_function)));
     *data = function;
     lua_pushcclosure(_pimpl->lua_state, cxx_function_trampoline, 1);

From 410b14c6e4b89d5087f03f6abcaf575b48db628f Mon Sep 17 00:00:00 2001
From: Minsoo Choo <minsoochoo0122@proton.me>
Date: Sun, 10 Mar 2024 21:03:22 -0400
Subject: [PATCH 13/24] Don't access static member through instance

---
 state.cpp | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/state.cpp b/state.cpp
index 1ea8309..1f2d90f 100644
--- a/state.cpp
+++ b/state.cpp
@@ -184,7 +184,7 @@ cxx_closure_trampoline(lua_State* raw_state)
     }
 
     auto* function = state.to_userdata< lutok::cxx_function >(
-        state.upvalue_index(nupvalues));
+        lutok::state::upvalue_index(nupvalues));
     return call_cxx_function_from_c(*function, raw_state);
 }
 
@@ -204,7 +204,7 @@ cxx_function_trampoline(lua_State* raw_state)
 {
     lutok::state state = lutok::state_c_gate::connect(raw_state);
     auto* function = state.to_userdata< lutok::cxx_function >(
-        state.upvalue_index(1));
+        lutok::state::upvalue_index(1));
     return call_cxx_function_from_c(*function, raw_state);
 }
 

From 8414b69e3d44aec5e54577073cdd9e2ccf872612 Mon Sep 17 00:00:00 2001
From: Minsoo Choo <minsoochoo0122@proton.me>
Date: Sun, 10 Mar 2024 21:04:50 -0400
Subject: [PATCH 14/24] Use make_shared()

---
 state.cpp | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/state.cpp b/state.cpp
index 1f2d90f..27c0a91 100644
--- a/state.cpp
+++ b/state.cpp
@@ -32,6 +32,7 @@ extern "C" {
 
 #include <cassert>
 #include <cstring>
+#include <memory>
 
 #include "c_gate.hpp"
 #include "exceptions.hpp"
@@ -244,7 +245,7 @@ lutok::state::state(void)
     lua_State* lua = luaL_newstate();
     if (lua == nullptr)
         throw lutok::error("lua open failed");
-    _pimpl.reset(new impl(lua, true));
+    _pimpl = std::make_shared<impl>(lua, true);
 }
 
 

From ccd96c53b2a35e7517062d02ebf644d73ef62fb0 Mon Sep 17 00:00:00 2001
From: Minsoo Choo <minsoochoo0122@proton.me>
Date: Sun, 10 Mar 2024 21:35:09 -0400
Subject: [PATCH 15/24] Do not include unused headers

---
 debug.cpp         | 1 -
 stack_cleaner.cpp | 1 -
 2 files changed, 2 deletions(-)

diff --git a/debug.cpp b/debug.cpp
index ff7ec04..c6e35a4 100644
--- a/debug.cpp
+++ b/debug.cpp
@@ -33,7 +33,6 @@
 #include <lutok/c_gate.hpp>
 #include <lutok/debug.hpp>
 #include <lutok/exceptions.hpp>
-#include <lutok/state.ipp>
 
 
 /// Internal implementation for lutok::debug.
diff --git a/stack_cleaner.cpp b/stack_cleaner.cpp
index ef546d2..dd5075a 100644
--- a/stack_cleaner.cpp
+++ b/stack_cleaner.cpp
@@ -27,7 +27,6 @@
 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
 #include <cassert>
-#include <cstring>
 
 #include "stack_cleaner.hpp"
 #include "state.ipp"

From 74466f9b092af5293a8f9c74b401a0cc408eb9be Mon Sep 17 00:00:00 2001
From: Minsoo Choo <minsoochoo0122@proton.me>
Date: Sun, 10 Mar 2024 21:38:15 -0400
Subject: [PATCH 16/24] Remove redundant static keyword

Static definition in anonymous namspace is redundant
---
 state.cpp | 16 ++++++++--------
 1 file changed, 8 insertions(+), 8 deletions(-)

diff --git a/state.cpp b/state.cpp
index 27c0a91..3e7f8c7 100644
--- a/state.cpp
+++ b/state.cpp
@@ -50,7 +50,7 @@ namespace {
 /// \param state The Lua C API state.
 ///
 /// \return The number of return values pushed onto the stack.
-static int
+int
 protected_getglobal(lua_State* state)
 {
     lua_getglobal(state, lua_tostring(state, -1));
@@ -67,7 +67,7 @@ protected_getglobal(lua_State* state)
 /// \param state The Lua C API state.
 ///
 /// \return The number of return values pushed onto the stack.
-static int
+int
 protected_gettable(lua_State* state)
 {
     lua_gettable(state, -2);
@@ -84,7 +84,7 @@ protected_gettable(lua_State* state)
 /// \param state The Lua C API state.
 ///
 /// \return The number of return values pushed onto the stack.
-static int
+int
 protected_next(lua_State* state)
 {
     const int more = lua_next(state, -2) != 0;
@@ -101,7 +101,7 @@ protected_next(lua_State* state)
 /// \param state The Lua C API state.
 ///
 /// \return The number of return values pushed onto the stack.
-static int
+int
 protected_setglobal(lua_State* state)
 {
     lua_setglobal(state, lua_tostring(state, -2));
@@ -118,7 +118,7 @@ protected_setglobal(lua_State* state)
 /// \param state The Lua C API state.
 ///
 /// \return The number of return values pushed onto the stack.
-static int
+int
 protected_settable(lua_State* state)
 {
     lua_settable(state, -3);
@@ -136,7 +136,7 @@ protected_settable(lua_State* state)
 ///
 /// \return The number of return values pushed onto the Lua stack by the
 /// function.
-static int
+int
 call_cxx_function_from_c(lutok::cxx_function function,
                          lua_State* raw_state) noexcept
 {
@@ -171,7 +171,7 @@ call_cxx_function_from_c(lutok::cxx_function function,
 /// \param raw_state The Lua C API state.
 ///
 /// \return The number of return values of the called closure.
-static int
+int
 cxx_closure_trampoline(lua_State* raw_state)
 {
     lutok::state state = lutok::state_c_gate::connect(raw_state);
@@ -200,7 +200,7 @@ cxx_closure_trampoline(lua_State* raw_state)
 /// \param raw_state The Lua C API state.
 ///
 /// \return The number of return values of the called function.
-static int
+int
 cxx_function_trampoline(lua_State* raw_state)
 {
     lutok::state state = lutok::state_c_gate::connect(raw_state);

From d790993f82c20d799192c6ea17c84a5aa004e334 Mon Sep 17 00:00:00 2001
From: Minsoo Choo <minsoochoo0122@proton.me>
Date: Sun, 10 Mar 2024 21:58:27 -0400
Subject: [PATCH 17/24] Use final when possible

---
 exceptions.hpp | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/exceptions.hpp b/exceptions.hpp
index ab90514..52bfa30 100644
--- a/exceptions.hpp
+++ b/exceptions.hpp
@@ -50,7 +50,7 @@ class error : public std::runtime_error {
 
 
 /// Exception for errors raised by the Lua API library.
-class api_error : public error {
+class api_error final : public error {
     /// Name of the Lua C API function that caused the error.
     std::string _api_function;
 
@@ -65,7 +65,7 @@ class api_error : public error {
 
 
 /// File not found error.
-class file_not_found_error : public error {
+class file_not_found_error final : public error {
     /// Name of the not-found file.
     std::string _filename;
 

From 366b7a85f477ffe24b93f7d13c971d4ac6aa9213 Mon Sep 17 00:00:00 2001
From: Minsoo Choo <minsoochoo0122@proton.me>
Date: Sun, 10 Mar 2024 22:40:28 -0400
Subject: [PATCH 18/24] Make function parameters const

---
 state.cpp | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/state.cpp b/state.cpp
index 3e7f8c7..c95b3c7 100644
--- a/state.cpp
+++ b/state.cpp
@@ -137,7 +137,7 @@ protected_settable(lua_State* state)
 /// \return The number of return values pushed onto the Lua stack by the
 /// function.
 int
-call_cxx_function_from_c(lutok::cxx_function function,
+call_cxx_function_from_c(const lutok::cxx_function function,
                          lua_State* raw_state) noexcept
 {
     char error_buf[1024];
@@ -228,7 +228,7 @@ struct lutok::state::impl {
     ///
     /// \param lua_ The Lua internal state.
     /// \param owned_ Whether we own the state or not.
-    impl(lua_State* lua_, bool owned_) :
+    impl(lua_State* lua_, const bool owned_) :
         lua_state(lua_),
         owned(owned_)
     {
@@ -678,7 +678,7 @@ lutok::state::push_boolean(const bool value) const
 /// \param function The C++ function to be pushed as a closure.
 /// \param nvalues The number of upvalues that the function receives.
 void
-lutok::state::push_cxx_closure(cxx_function function, const int nvalues) const
+lutok::state::push_cxx_closure(const cxx_function function, const int nvalues) const
 {
     auto *data = static_cast< cxx_function* >(
         lua_newuserdata(_pimpl->lua_state, sizeof(cxx_function)));
@@ -694,7 +694,7 @@ lutok::state::push_cxx_closure(cxx_function function, const int nvalues) const
 ///
 /// \param function The C++ function to be pushed.
 void
-lutok::state::push_cxx_function(cxx_function function) const
+lutok::state::push_cxx_function(const cxx_function function) const
 {
     auto *data = static_cast< cxx_function* >(
         lua_newuserdata(_pimpl->lua_state, sizeof(cxx_function)));

From ba2c74a19636a1dcc08b3c1186dea1a4d28a6e5c Mon Sep 17 00:00:00 2001
From: Minsoo Choo <minsoochoo0122@proton.me>
Date: Sun, 10 Mar 2024 22:40:54 -0400
Subject: [PATCH 19/24] Remove redundant static_cast

---
 c_gate.cpp | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/c_gate.cpp b/c_gate.cpp
index 7de7ad3..deddd26 100644
--- a/c_gate.cpp
+++ b/c_gate.cpp
@@ -60,7 +60,7 @@ lutok::state_c_gate::~state_c_gate(void) = default;
 lutok::state
 lutok::state_c_gate::connect(lua_State* raw_state)
 {
-    return state(static_cast< void* >(raw_state));
+    return state(raw_state);
 }
 
 

From 5494f7ae035fbdc415f7b499bec1f2d78a4fa3f3 Mon Sep 17 00:00:00 2001
From: Minsoo Choo <minsoochoo0122@proton.me>
Date: Sun, 10 Mar 2024 22:58:43 -0400
Subject: [PATCH 20/24] Use explicit constructor

---
 test_utils.hpp | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/test_utils.hpp b/test_utils.hpp
index 9cbb8ed..38f3a92 100644
--- a/test_utils.hpp
+++ b/test_utils.hpp
@@ -107,7 +107,7 @@ class stack_balance_checker {
     ///     validate upon exit that the item is still there.  This is an attempt
     ///     to ensure that already-existing items are not removed from the stack
     ///     by the code under test.
-    stack_balance_checker(lutok::state& state_,
+    explicit stack_balance_checker(lutok::state& state_,
                           const bool with_sentinel_ = true) :
         _state(state_),
         _with_sentinel(with_sentinel_),

From 72f2a93ae435cf1b1751faee8942a83b07b5ebc0 Mon Sep 17 00:00:00 2001
From: Minsoo Choo <minsoochoo0122@proton.me>
Date: Sun, 10 Mar 2024 23:00:35 -0400
Subject: [PATCH 21/24] Don't access static member through instance

---
 state_test.cpp | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/state_test.cpp b/state_test.cpp
index 40c70a6..b9e5af3 100644
--- a/state_test.cpp
+++ b/state_test.cpp
@@ -109,8 +109,8 @@ static int
 c_get_upvalues(lua_State* raw_state)
 {
     lutok::state state = lutok::state_c_gate::connect(raw_state);
-    const int i1 = lua_tointeger(raw_state, state.upvalue_index(1));
-    const int i2 = lua_tointeger(raw_state, state.upvalue_index(2));
+    const int i1 = lua_tointeger(raw_state, lutok::state::upvalue_index(1));
+    const int i2 = lua_tointeger(raw_state, lutok::state::upvalue_index(2));
     lua_pushinteger(raw_state, i1);
     lua_pushinteger(raw_state, i2);
     return 2;

From e4c499fb1f569ddf6ae6598238691e8b786444a9 Mon Sep 17 00:00:00 2001
From: Minsoo Choo <minsoochoo0122@proton.me>
Date: Sun, 10 Mar 2024 23:04:51 -0400
Subject: [PATCH 22/24] Add [[nodiscard]] to some functions

---
 c_gate.hpp     |  2 +-
 debug.hpp      | 20 ++++++++++----------
 exceptions.hpp |  4 ++--
 state.hpp      | 32 ++++++++++++++++----------------
 4 files changed, 29 insertions(+), 29 deletions(-)

diff --git a/c_gate.hpp b/c_gate.hpp
index f98e276..eceb846 100644
--- a/c_gate.hpp
+++ b/c_gate.hpp
@@ -62,7 +62,7 @@ class state_c_gate {
 
     static state connect(lua_State*);
 
-    lua_State* c_state(void) const;
+    [[nodiscard]] lua_State* c_state(void) const;
 };
 
 
diff --git a/debug.hpp b/debug.hpp
index a810ae5..1a125bc 100644
--- a/debug.hpp
+++ b/debug.hpp
@@ -64,16 +64,16 @@ class debug {
     void get_info(state&, const std::string&) const;
     void get_stack(state&, int) const;
 
-    int event(void) const;
-    std::string name(void) const;
-    std::string name_what(void) const;
-    std::string what(void) const;
-    std::string source(void) const;
-    int current_line(void) const;
-    int n_ups(void) const;
-    int line_defined(void) const;
-    int last_line_defined(void) const;
-    std::string short_src(void) const;
+    [[nodiscard]] int event(void) const;
+    [[nodiscard]] std::string name(void) const;
+    [[nodiscard]] std::string name_what(void) const;
+    [[nodiscard]] std::string what(void) const;
+    [[nodiscard]] std::string source(void) const;
+    [[nodiscard]] int current_line(void) const;
+    [[nodiscard]] int n_ups(void) const;
+    [[nodiscard]] int line_defined(void) const;
+    [[nodiscard]] int last_line_defined(void) const;
+    [[nodiscard]] std::string short_src(void) const;
 };
 
 
diff --git a/exceptions.hpp b/exceptions.hpp
index 52bfa30..6465b50 100644
--- a/exceptions.hpp
+++ b/exceptions.hpp
@@ -60,7 +60,7 @@ class api_error final : public error {
 
     static api_error from_stack(state&, const std::string&);
 
-    const std::string& api_function(void) const;
+    [[nodiscard]] const std::string& api_function(void) const;
 };
 
 
@@ -73,7 +73,7 @@ class file_not_found_error final : public error {
     explicit file_not_found_error(const std::string&);
     ~file_not_found_error(void) noexcept override;
 
-    const std::string& filename(void) const;
+    [[nodiscard]] const std::string& filename(void) const;
 };
 
 
diff --git a/state.hpp b/state.hpp
index a9d8776..314804e 100644
--- a/state.hpp
+++ b/state.hpp
@@ -74,12 +74,12 @@ class state {
     /// Pointer to the shared internal implementation.
     std::shared_ptr< impl > _pimpl;
 
-    void* new_userdata_voidp(size_t) const;
-    void* to_userdata_voidp(int) const;
+    [[nodiscard]] void* new_userdata_voidp(size_t) const;
+    [[nodiscard]] void* to_userdata_voidp(int) const;
 
     friend class state_c_gate;
     explicit state(void*);
-    void* raw_state(void) const;
+    [[nodiscard]] void* raw_state(void) const;
 
 public:
     state(void);
@@ -88,18 +88,18 @@ class state {
     void close(void) const;
     void get_global(const std::string&);
     void get_global_table(void) const;
-    bool get_metafield(int, const std::string&) const;
-    bool get_metatable(int) const;
+    [[nodiscard]] bool get_metafield(int, const std::string&) const;
+    [[nodiscard]] bool get_metatable(int) const;
     void get_table(int);
-    int get_top(void) const;
+    [[nodiscard]] int get_top(void) const;
     void insert(int) const;
-    bool is_boolean(int) const;
-    bool is_function(int) const;
-    bool is_nil(int) const;
-    bool is_number(int) const;
-    bool is_string(int) const;
-    bool is_table(int) const;
-    bool is_userdata(int) const;
+    [[nodiscard]] bool is_boolean(int) const;
+    [[nodiscard]] bool is_function(int) const;
+    [[nodiscard]] bool is_nil(int) const;
+    [[nodiscard]] bool is_number(int) const;
+    [[nodiscard]] bool is_string(int) const;
+    [[nodiscard]] bool is_table(int) const;
+    [[nodiscard]] bool is_userdata(int) const;
     void load_file(const std::string&);
     void load_string(const std::string&);
     void new_table(void) const;
@@ -123,10 +123,10 @@ class state {
     void set_global(const std::string&);
     void set_metatable(int) const;
     void set_table(int);
-    bool to_boolean(int) const;
-    long to_integer(int) const;
+    [[nodiscard]] bool to_boolean(int) const;
+    [[nodiscard]] long to_integer(int) const;
     template< typename Type > Type* to_userdata(int);
-    std::string to_string(int) const;
+    [[nodiscard]] std::string to_string(int) const;
     static int upvalue_index(int);
 };
 

From 1cd22fc076b80389a6fcb4a9bad03b3302602c5b Mon Sep 17 00:00:00 2001
From: Minsoo Choo <minsoochoo0122@proton.me>
Date: Mon, 11 Mar 2024 10:35:51 -0400
Subject: [PATCH 23/24] Throw with runtime_err

---
 state_test.cpp | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/state_test.cpp b/state_test.cpp
index b9e5af3..a69f6d9 100644
--- a/state_test.cpp
+++ b/state_test.cpp
@@ -158,7 +158,7 @@ cxx_divide(lutok::state& state)
     if (divisor == 0)
         throw std::runtime_error("Divisor is 0");
     if (dividend < 0 || divisor < 0)
-        throw std::string("Cannot divide negative numbers");
+        throw std::runtime_error("Cannot divide negative numbers");
     state.push_integer(dividend / divisor);
     state.push_integer(dividend % divisor);
     return 2;

From c2419931862b1c0d62d801fd86096610aa5a8135 Mon Sep 17 00:00:00 2001
From: Minsoo Choo <minsoochoo0122@proton.me>
Date: Mon, 11 Mar 2024 11:06:42 -0400
Subject: [PATCH 24/24] Correct return type

---
 state.cpp      | 2 +-
 state.hpp      | 2 +-
 state_test.cpp | 2 +-
 3 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/state.cpp b/state.cpp
index c95b3c7..811bf49 100644
--- a/state.cpp
+++ b/state.cpp
@@ -835,7 +835,7 @@ lutok::state::to_boolean(const int index) const
 /// \param index The second parameter to lua_tointeger.
 ///
 /// \return The return value of lua_tointeger.
-long
+int
 lutok::state::to_integer(const int index) const
 {
     assert(is_number(index));
diff --git a/state.hpp b/state.hpp
index 314804e..65d4abc 100644
--- a/state.hpp
+++ b/state.hpp
@@ -124,7 +124,7 @@ class state {
     void set_metatable(int) const;
     void set_table(int);
     [[nodiscard]] bool to_boolean(int) const;
-    [[nodiscard]] long to_integer(int) const;
+    [[nodiscard]] int to_integer(int) const;
     template< typename Type > Type* to_userdata(int);
     [[nodiscard]] std::string to_string(int) const;
     static int upvalue_index(int);
diff --git a/state_test.cpp b/state_test.cpp
index a69f6d9..aa15cca 100644
--- a/state_test.cpp
+++ b/state_test.cpp
@@ -802,7 +802,7 @@ ATF_TEST_CASE_BODY(push_cxx_function__fail_anything)
     lua_setglobal(raw(state), "cxx_divide");
 
     ATF_REQUIRE(luaL_dostring(raw(state), "return cxx_divide(-3, -1)") != 0);
-    ATF_REQUIRE_MATCH("Unhandled exception", lua_tostring(raw(state), -1));
+    ATF_REQUIRE_MATCH("Cannot divide negative numbers", lua_tostring(raw(state), -1));
     lua_pop(raw(state), 1);
 }