diff --git a/luprex/core/cpp/luastack.cpp b/luprex/core/cpp/luastack.cpp
index 6ed7fe22..4a2bd95b 100644
--- a/luprex/core/cpp/luastack.cpp
+++ b/luprex/core/cpp/luastack.cpp
@@ -34,10 +34,6 @@ const LuaFunctionReg *LuaFunctionReg::lookup(lua_CFunction fn) {
 
 LuaFunctionReg *LuaFunctionReg::LuaFunctionRegistry;
 
-bool LuaStack::issortablekey(LuaSlot s) const {
-    int type = lua_type(L_, s);
-    return (type == LUA_TBOOLEAN) || (type == LUA_TNUMBER) || (type == LUA_TSTRING);
-}
 
 bool LuaStack::ckboolean(LuaSlot s) const {
     luaL_checktype(L_, s, LUA_TBOOLEAN);
@@ -106,27 +102,6 @@ int LuaStack::result() {
     return nret_;
 }
 
-void LuaStack::pop_any_value(lua_Integer &s) const {
-    luaL_checktype(L_, -1, LUA_TNUMBER);
-    s = lua_tointeger(L_, -1);
-    lua_pop(L_, 1);
-}
-
-void LuaStack::pop_any_value(lua_Number &s) const {
-    luaL_checktype(L_, -1, LUA_TNUMBER);
-    s = lua_tonumber(L_, -1);
-    lua_pop(L_, 1);
-}
-    
-
-void LuaStack::pop_any_value(std::string &s) const {
-    luaL_checktype(L_, -1, LUA_TSTRING);
-    size_t len;
-    const char *str = lua_tolstring(L_, -1, &len);
-    s = std::string(str, len);
-    lua_pop(L_, 1);
-}
-
 void LuaStack::clearmetatable(LuaSlot tab) const {
     lua_pushnil(L_);
     lua_setmetatable(L_, tab);
@@ -148,15 +123,6 @@ bool LuaStack::getmetatable(LuaSlot mt, LuaSlot tab) const {
     }
 }
 
-void LuaStack::checknometa(LuaSlot index) const {
-    if (lua_istable(L_, index)) {
-        if (!lua_getmetatable(L_, index)) {
-            return;
-        }
-    }
-    luaL_error(L_, "expected simple table with no metatable");
-}
-
 int LuaStack::next(LuaSlot tab, LuaSlot key, LuaSlot value) const {
     lua_pushvalue(L_, key);
     int ret = lua_next(L_, tab);
@@ -359,6 +325,10 @@ int64_t LuaStack::tanid(LuaSlot tab) const {
     return result;
 }
 
+bool LuaStack::issortablekey(LuaSlot s) const {
+    int type = lua_type(L_, s);
+    return (type == LUA_TBOOLEAN) || (type == LUA_TNUMBER) || (type == LUA_TSTRING);
+}
 
 void LuaStack::movesortablekey(LuaSlot key, LuaStack &otherstack, LuaSlot otherslot) {
     int type = lua_type(L_, key);
@@ -379,25 +349,23 @@ void LuaStack::movesortablekey(LuaSlot key, LuaStack &otherstack, LuaSlot others
         break;
     }
     default:
-        luaL_error(L_, "movesortablekey: not a sortable key");
+        assert(false && "movesortablekey: not a sortable key");
     }
 }
 
 void LuaStack::makesubtable(LuaSlot sub, LuaSlot tab, const char *name) const {
+    assert(istable(tab));
     rawget(sub, tab, name);
     if (istable(sub)) {
         return;
-    } else if (isnil(sub)) {
+    } else {
         newtable(sub);
         rawset(tab, name, sub);
-        return;
-    } else {
-        luaL_error(L_, "%s is not a table", name);
     }
 }
 
 void LuaStack::cleartable(LuaSlot tab, bool clearmeta) const {
-    checktable(tab);
+    assert(istable(tab));
     lua_pushnil(L_);
     while (lua_next(L_, tab.index()) != 0) {
         lua_pop(L_, 1); // Pop the old value.
diff --git a/luprex/core/cpp/luastack.hpp b/luprex/core/cpp/luastack.hpp
index 04626fa0..fc44d0de 100644
--- a/luprex/core/cpp/luastack.hpp
+++ b/luprex/core/cpp/luastack.hpp
@@ -304,12 +304,6 @@ private:
     void push_any_value(lua_CFunction s) const { lua_pushcfunction(L_, s); }
     void push_any_value(bool b) const { lua_pushboolean(L_, b ? 1:0); }
 
-    // Pop any value off the stack, by type.
-    void pop_any_value(LuaSlot &s) const { lua_replace(L_, s); }
-    void pop_any_value(lua_Integer &s) const;
-    void pop_any_value(lua_Number &s) const;
-    void pop_any_value(std::string &s) const;
-
     // Push multiple values on the stack, in order, by type.
     template<typename T0, typename... T>
     void push_any_values(T0 arg0, T... args) {
@@ -353,7 +347,6 @@ public:
     bool isboolean(LuaSlot s) const { return lua_type(L_, s) == LUA_TBOOLEAN; }
     bool isnil(LuaSlot s) const { return lua_type(L_, s) == LUA_TNIL; }
     bool iscfunction(LuaSlot s) const { return lua_iscfunction(L_, s) != 0; }
-    bool issortablekey(LuaSlot s) const;
 
     void checktable(LuaSlot index) const { checktype(index, LUA_TTABLE); }
     void checkstring(LuaSlot index) const { checktype(index, LUA_TSTRING); }
@@ -373,7 +366,6 @@ public:
     void clearmetatable(LuaSlot tab) const;
     void setmetatable(LuaSlot tab, LuaSlot mt) const;
     bool getmetatable(LuaSlot mt, LuaSlot tab) const;
-    void checknometa(LuaSlot index) const;
 
     void newtable(LuaSlot target) const;
     void createtable(LuaSlot target, int narr, int nrec) const;
@@ -415,6 +407,12 @@ public:
     // this module.
     int64_t tanid(LuaSlot tab) const;
 
+    // Return true if the value is a sortable key (string, number, or boolean).
+    bool issortablekey(LuaSlot s) const;
+
+    // Move a sortable key (string, number, or boolean) from one lua
+    // environment to another lua environment.  WARNING: this assert-fails
+    // if the value is not a sortable key.
     void movesortablekey(LuaSlot val, LuaStack &other, LuaSlot otherslot);
 
     bool rawequal(LuaSlot v1, LuaSlot v2) const {
@@ -428,23 +426,22 @@ public:
         return result;
     }
     
-    template<typename T1, typename T2>
-    void set(T1 &target, T2 value) const {
+    template<typename VT>
+    void set(LuaSlot target, VT value) const {
         push_any_value(value);
-        pop_any_value(target);
+        lua_replace(L_, target);
     }
 
-    template<typename RT, typename KT>
-    void rawget(RT &target, LuaSlot tab, KT key) const {
+    template<typename KT>
+    void rawget(LuaSlot target, LuaSlot tab, KT key) const {
         push_any_value(key);
         lua_rawget(L_, tab);
-        pop_any_value(target);
+        lua_replace(L_, target);
     }
 
-    template<typename RT>
-    void rawget(RT &target, LuaSlot tab, int key) const {
-        lua_rawgeti(L_, tab, key);
-        pop_any_value(target);
+    void rawget(LuaSlot target, LuaSlot tab, int key) const {
+         lua_rawgeti(L_, tab, key);
+         lua_replace(L_, target);
     }
     
     template<typename KT, typename VT>
diff --git a/luprex/core/cpp/table.cpp b/luprex/core/cpp/table.cpp
index 794088b9..5a25c1a2 100644
--- a/luprex/core/cpp/table.cpp
+++ b/luprex/core/cpp/table.cpp
@@ -118,6 +118,7 @@ LuaDefine(table_clear, "table,metaflag", "clear all keys, and optionally the met
     LuaArg tab, clearmeta;
     LuaVar metatable, metafield;
     LuaStack LS(L, tab, clearmeta, metatable, metafield);
+    LS.checktable(tab);
     if (LS.ckboolean(clearmeta)) {
         LS.getmetatable(metatable, tab);
         if (LS.istable(metatable)) {