diff --git a/luprex/core/cpp/invocation.hpp b/luprex/core/cpp/invocation.hpp
index 3c728327..a006a3ef 100644
--- a/luprex/core/cpp/invocation.hpp
+++ b/luprex/core/cpp/invocation.hpp
@@ -21,6 +21,7 @@ public:
         KIND_INVALID,
         KIND_PLAN,
         KIND_LUA,
+        KIND_FLUSH_PRINTS,
     };
 
 private:
diff --git a/luprex/core/cpp/luastack.cpp b/luprex/core/cpp/luastack.cpp
index b7245ac6..4238ace2 100644
--- a/luprex/core/cpp/luastack.cpp
+++ b/luprex/core/cpp/luastack.cpp
@@ -315,7 +315,7 @@ void LuaStack::makesubtable(LuaSlot sub, LuaSlot tab, const char *name) const {
     }
 }
 
-void LuaStack::cleartable(LuaSlot tab) const {
+void LuaStack::cleartable(LuaSlot tab, bool clearmeta) const {
     checktable(tab);
     lua_pushnil(L_);
     while (lua_next(L_, tab.index()) != 0) {
@@ -324,6 +324,10 @@ void LuaStack::cleartable(LuaSlot tab) const {
         lua_pushnil(L_); // Push the new value.
         lua_rawset(L_, tab.index());
     }
+    if (clearmeta) {
+        lua_pushnil(L_);
+        lua_setmetatable(L_, tab.index());
+    }
 }
 
 int LuaStack::rawlen(LuaSlot obj) const {
diff --git a/luprex/core/cpp/luastack.hpp b/luprex/core/cpp/luastack.hpp
index 89718f84..f3405f76 100644
--- a/luprex/core/cpp/luastack.hpp
+++ b/luprex/core/cpp/luastack.hpp
@@ -380,7 +380,7 @@ public:
     lua_State *newthread(LuaSlot target) const;
     void getglobaltable(LuaSlot gltab) const;
     void makesubtable(LuaSlot sub, LuaSlot tab, const char *name) const;
-    void cleartable(LuaSlot tab) const;
+    void cleartable(LuaSlot tab, bool clearmeta) const;
 
     int rawlen(LuaSlot val) const;
     
diff --git a/luprex/core/cpp/printbuffer.cpp b/luprex/core/cpp/printbuffer.cpp
index 42404afe..56d70311 100644
--- a/luprex/core/cpp/printbuffer.cpp
+++ b/luprex/core/cpp/printbuffer.cpp
@@ -46,9 +46,6 @@ void PrintBuffer::discard_upto(int n) {
         lines_.pop_front();
         first_line_ += 1;
     }
-    if (first_line_ < n) {
-        first_line_ = n;
-    }
     if (first_unchecked_ < first_line_) {
         first_unchecked_ = first_line_;
     }
@@ -95,6 +92,9 @@ void PrintBuffer::patch(StreamBuffer *sb) {
     }
     first_unchecked_ = first_line_ + lines_.size();
     discard_upto(auth_first);
+    if (first_line_ < auth_first) {
+        first_line_ = auth_first;
+    }
 }
 
 LuaDefine(unittests_printbuffer, "c") {
@@ -110,7 +110,7 @@ LuaDefine(unittests_printbuffer, "c") {
     pbm.discard_upto(2);
     LuaAssertStrEq(L, pbm.debug_string(), "2,6:baz;a;b;c;");
     pbm.discard_upto(8);
-    LuaAssertStrEq(L, pbm.debug_string(), "8,8:");
+    LuaAssertStrEq(L, pbm.debug_string(), "6,6:");
 
     LuaAssertStrEq(L, pbs.debug_string(), "0,0:");
     pbs.add_string("foo\nbar\nbaz\n");
@@ -120,7 +120,7 @@ LuaDefine(unittests_printbuffer, "c") {
     pbs.discard_upto(2);
     LuaAssertStrEq(L, pbs.debug_string(), "2,2:baz;a;b;c;");
     pbs.discard_upto(8);
-    LuaAssertStrEq(L, pbs.debug_string(), "8,8:");
+    LuaAssertStrEq(L, pbs.debug_string(), "6,6:");
 
     pbm.clear();
     pbs.clear();
diff --git a/luprex/core/cpp/source.cpp b/luprex/core/cpp/source.cpp
index 3d6ee224..e1e8e3c3 100644
--- a/luprex/core/cpp/source.cpp
+++ b/luprex/core/cpp/source.cpp
@@ -172,7 +172,7 @@ void SourceDB::diff(const SourceDB &auth, StreamBuffer *sb) {
     SLS.result();
 }
 
-void SourceDB::patch(StreamBuffer *sb) {
+bool SourceDB::patch(StreamBuffer *sb) {
     lua_State *L = lua_state_;
     LuaVar db, info;
     LuaStack LS(L, db, info);
@@ -195,7 +195,7 @@ void SourceDB::patch(StreamBuffer *sb) {
         }
     }
     LS.result();
-    if (nupdates > 0) rebuild(false);
+    return (nupdates > 0);
 }
 
 void SourceDB::set(const std::string &fn, const std::string &code, int sequence) {
@@ -250,7 +250,7 @@ void SourceDB::update(const util::LuaSourceVec &source) {
         LS.newtable(sourcedb);
         LS.rawset(LuaRegistry, "sourcedb", sourcedb);
     }
-    LS.cleartable(sourcedb);
+    LS.cleartable(sourcedb, true);
 
     for (int i = 0; i < int(source.size()); i++) {
         const std::string &file = source[i].first;
@@ -278,8 +278,10 @@ static void source_clear_globals(lua_State *L) {
     LS.rawset(globtab, "_G", LuaNil);
     LS.set(classname, LuaNil);
     while (LS.next(globtab, classname, classtab) != 0) {
-        if (LS.istable(classtab)) {
-            table_clear(LS, classtab);
+        if (LS.rawequal(globtab, classtab)) {
+            LS.rawset(globtab, classname, LuaNil);
+        } else if (LS.istable(classtab)) {
+            LS.cleartable(classtab, true);
         } else {
             LS.rawset(globtab, classname, LuaNil);
         }
@@ -292,6 +294,8 @@ static void source_clear_globals(lua_State *L) {
 // Load all the 'LuaDefine' C functions into the lua state.
 //
 static void source_load_cfunctions(lua_State *L) {
+    LuaVar classobj;
+    LuaStack LS(L, classobj);
     auto regs = LuaFunctionReg::all();
     for (const LuaFunctionReg *r : regs) {
         const std::string &name = r->get_name();
@@ -307,24 +311,22 @@ static void source_load_cfunctions(lua_State *L) {
         lua_CFunction func = r->get_func();
         std::string mode = r->get_mode();
         if (mode.find('c') != std::string::npos) { // Insert into class
-            lua_pushlstring(L, classname.c_str(), classname.size());
-            lfn_source_makeclass(L);
-            lua_pushcfunction(L, func);
-            lua_setfield(L, -2, funcname.c_str());
+            LS.makeclass(classobj, classname);
+            LS.rawset(classobj, funcname, func);
         }
         if (mode.find('f') != std::string::npos) { // Make global function
-            lua_pushcfunction(L, func);
-            lua_setglobal(L, funcname.c_str());
+            LS.getglobaltable(classobj);
+            LS.rawset(classobj, funcname, func);
         }
     }
+    LS.result();
 }
 
 // Run all the closures from the source database.
 //
-static void source_load_lfunctions(lua_State *L, bool print_errors) {
-    LuaRet errors;
+static std::string source_load_lfunctions(lua_State *L) {
     LuaVar sourcedb, key, info, seq, closure, err;
-    LuaStack LS(L, sourcedb, errors, key, info, seq, closure, err);
+    LuaStack LS(L, sourcedb, key, info, seq, closure, err);
 
     // Get the source database.
     LS.rawget(sourcedb, LuaRegistry, "sourcedb");
@@ -349,9 +351,7 @@ static void source_load_lfunctions(lua_State *L, bool print_errors) {
 
         // If there's already an error in the sourcedb, collect it.
         if (!LS.isfunction(closure)) {
-            if (print_errors) {
-                errss << LS.ckstring(closure) << "\n";
-            }
+            errss << LS.ckstring(closure) << "\n";
             continue;
         }
         
@@ -362,22 +362,17 @@ static void source_load_lfunctions(lua_State *L, bool print_errors) {
             errss << LS.ckstring(err);
         }
     }
-    LS.set(errors, errss.str());
     LS.result();
+    return errss.str();
 }
 
-void SourceDB::rebuild(bool print_errors) {
+std::string SourceDB::rebuild() {
     lua_State *L = lua_state_;
-    LuaVar errs;
-    LuaStack LS(L, errs);
     source_clear_globals(L);
     source_install_builtins(L);
     source_load_cfunctions(L);
-    source_load_lfunctions(L, print_errors);
-    lua_replace(L, errs.index());
-    std::string errstr = LS.ckstring(errs);
-    std::cerr << errstr;
-    LS.result();
+    std::string errs = source_load_lfunctions(L);
+    return errs;
 }
 
 void SourceDB::run_unittests() {
diff --git a/luprex/core/cpp/source.hpp b/luprex/core/cpp/source.hpp
index e6b8dfea..fba7355b 100644
--- a/luprex/core/cpp/source.hpp
+++ b/luprex/core/cpp/source.hpp
@@ -141,18 +141,21 @@ public:
     //
     // Rebuild the lua environment: clear it out, then reinstall all the
     // functions that should be there.  See above for more information.
-    // If an error exists in any of the source files, or when loading any
-    // of the closures, the error can optionally be printed or ignored.
     //
-    void rebuild(bool print_errors);
-
+    // Any error messages will be collected into a single long string
+    // containing one error per line, and returned.  If the return value
+    // is the empty string, there were no errors.
+    //
+    std::string rebuild();
+    
     // Difference transmission.
     //
     // Note: The patch routine applies the differences to the source
     // database, and if there are any changes, it does a source rebuild.
+    // The patch routine returns true if anything was modified.
     //
     void diff(const SourceDB &auth, StreamBuffer *sb);
-    void patch(StreamBuffer *sb);
+    bool patch(StreamBuffer *sb);
 
     // run_unittests
     //
@@ -170,19 +173,6 @@ public:
     std::string get(const std::string &fn);
 };
 
-// The Lua 'makeclass' operator.
-//
-// Creates a table in the global environment with the specified name.
-// Adds a __class field and an __index field, and an action subtable.
-// If there's already a table with this name in the global environment,
-// leaves it there, and repairs the __class and __index fields.
-//
-int lfn_source_makeclass(lua_State *L);
-
-// Return true if the specified table is a class created by 'makeclass'
-//
-int lfn_source_isclass(lua_State *L);
-
 #endif // SOURCE_HPP
 
 
diff --git a/luprex/core/cpp/table.cpp b/luprex/core/cpp/table.cpp
index 41ee306f..cf156449 100644
--- a/luprex/core/cpp/table.cpp
+++ b/luprex/core/cpp/table.cpp
@@ -128,14 +128,23 @@ LuaDefine(table_count, "c") {
     return 1;
 }
 
-void table_clear(LuaStack &LS0, LuaSlot table) {
-    LS0.cleartable(table);
-}
-
 LuaDefine(table_clear, "c") {
-    LuaArg tab;
-    LuaStack LS(L, tab);
-    table_clear(LS, tab);
+    LuaArg tab, clearmeta;
+    LuaVar metatable, metafield;
+    LuaStack LS(L, tab, clearmeta, metatable, metafield);
+    if (LS.ckboolean(clearmeta)) {
+        LS.getmetatable(metatable, tab);
+        if (LS.istable(metatable)) {
+            LS.rawget(metafield, metatable, "__metatable");
+            if (!LS.isnil(metafield)) {
+                luaL_error(L, "Cannot clear metatable.");
+                return LS.result();
+            }
+        }
+        LS.cleartable(tab, true);
+    } else {
+        LS.cleartable(tab, false);
+    }
     return LS.result();
 }
 
diff --git a/luprex/core/cpp/table.hpp b/luprex/core/cpp/table.hpp
index 20d133a5..99d3e883 100644
--- a/luprex/core/cpp/table.hpp
+++ b/luprex/core/cpp/table.hpp
@@ -12,13 +12,6 @@
 
 #include "luastack.hpp"
 
-// table_clear
-//
-// Remove all key/value pairs from the table.  Does not remove
-// the metatable.
-//
-void table_clear(LuaStack &LS0, LuaSlot tab);
-
 // table_equal
 //
 // True if two tables contain the same key/value pairs.
diff --git a/luprex/core/cpp/textgame.cpp b/luprex/core/cpp/textgame.cpp
index eca08921..e2488d51 100644
--- a/luprex/core/cpp/textgame.cpp
+++ b/luprex/core/cpp/textgame.cpp
@@ -180,6 +180,11 @@ void TextGame::channel_printbuffer() {
         std::cerr << "* " << printbuffer->nth(printbuffer_line_) << std::endl;
         printbuffer_line_ += 1;
     }
+    if (printbuffer_line_ > printbuffer->first_line()) {
+        InvocationData data;
+        Invocation inv(Invocation::KIND_FLUSH_PRINTS, actor_id_, actor_id_, std::to_string(printbuffer_line_), data);
+        world_->invoke(inv);
+    }
 }
 
 
diff --git a/luprex/core/cpp/world-core.cpp b/luprex/core/cpp/world-core.cpp
index 06c45425..f4c39792 100644
--- a/luprex/core/cpp/world-core.cpp
+++ b/luprex/core/cpp/world-core.cpp
@@ -67,7 +67,11 @@ World::World(util::WorldType wt) {
     // Initialize the SourceDB.  At this stage, the sourcedb is
     // empty, so it's just populating the lua builtins.
     source_db_.init(state());
-    source_db_.rebuild(true);
+    std::string srcerrs = source_db_.rebuild();
+
+    // There shouldn't be any lua errors in the sourceDB at this
+    // point, since there's no lua code in the sourceDB.
+    assert(srcerrs == "");
 
     LS.result();
     assert (stack_is_clear());
@@ -212,8 +216,7 @@ void World::tangible_delete(int64_t id) {
     assert(LS.istable(database));
     
     // Clear out the database.
-    LS.clearmetatable(database);
-    LS.cleartable(database);
+    LS.cleartable(database, true);
     LS.settabletype(database, LUA_TT_DEADTANGIBLE);
 
     // Remove the lua portion from the tangibles table.
@@ -252,6 +255,7 @@ World::Redirects World::fetch_redirects() {
 }
 
 int64_t World::create_login_actor() {
+    assert(stack_is_clear());
     int64_t id = id_global_pool_.get_one();
     Tangible *tan = tangible_make(state(), id, "nowhere", true);
     LuaArg database;
@@ -323,10 +327,23 @@ void World::update_gui(int64_t actor_id, int64_t place_id, Gui *gui) {
 }
 
 void World::update_source(util::LuaSourcePtr source) {
+    assert(stack_is_clear());
     if (source != nullptr) {
         source_db_.update(*source);
-        source_db_.rebuild(true);
+        assert(stack_is_clear());
+        std::string errs = source_db_.rebuild();
+        // I don't have a good place to send the error messages right
+        // now.  The engine needs a catch-all place to send errors that
+        // occur at unexpected times.
+        std::cerr << errs;
     }
+    assert(stack_is_clear());
+}
+
+void World::run_unittests() {
+    assert(stack_is_clear());
+    source_db_.run_unittests();
+    assert(stack_is_clear());
 }
 
 void World::invoke(const Invocation &inv) {
@@ -337,6 +354,9 @@ void World::invoke(const Invocation &inv) {
     case Invocation::KIND_LUA:
         invoke_lua(inv.actor(), inv.place(), inv.action(), inv.data());
         break;
+    case Invocation::KIND_FLUSH_PRINTS:
+        invoke_flush_prints(inv.actor(), inv.place(), inv.action(), inv.data());
+        break;
     default:
         // Do nothing.  Standard behavior for any invalid command is to
         // simply do nothing at all.  Perhaps eventually we may add a flag
@@ -347,6 +367,28 @@ void World::invoke(const Invocation &inv) {
     }
 }
 
+void World::invoke_flush_prints(int64_t actor_id, int64_t place_id, const std::string &action, const InvocationData &data) {
+    assert(stack_is_clear());
+    // Check argument sanity.
+    if (actor_id != place_id) {
+        return;
+    }
+    int line = util::strtoint(action, -1);
+    if (line < 0) {
+        return;
+    }
+    Tangible *tactor = tangible_get(actor_id);
+    if (tactor == nullptr) {
+        return;
+    }
+    if (tactor->print_buffer_ == nullptr) {
+        return;
+    }
+    tactor->print_buffer_->discard_upto(line);
+    assert(stack_is_clear());
+}
+
+
 void World::invoke_lua(int64_t actor_id, int64_t place_id, const std::string &action, const InvocationData &data) {
     assert(stack_is_clear());
 
diff --git a/luprex/core/cpp/world-diffxmit.cpp b/luprex/core/cpp/world-diffxmit.cpp
index b33aa610..e1011dec 100644
--- a/luprex/core/cpp/world-diffxmit.cpp
+++ b/luprex/core/cpp/world-diffxmit.cpp
@@ -1,4 +1,5 @@
 #include "world.hpp"
+#include <iostream>
 
 util::IdVector World::get_visible_union(int64_t actor_id, World *master) {
     return util::sort_union_id_vectors(
@@ -263,7 +264,13 @@ void World::diff_tanclass(int64_t actor_id, World *master, StreamBuffer *xsb) {
 }
 
 void World::patch_source(StreamBuffer *sb) {
-    source_db_.patch(sb);
+    bool modified = source_db_.patch(sb);
+    if (modified) {
+        std::string errs = source_db_.rebuild();
+        // TODO: I don't currently have any good place to send the
+        // error messages.  This is a stopgap.
+        std::cerr << errs;
+    }
 }
 
 void World::diff_source(World *master, StreamBuffer *sb) {
diff --git a/luprex/core/cpp/world.hpp b/luprex/core/cpp/world.hpp
index 3c2bd2d5..62ecb997 100644
--- a/luprex/core/cpp/world.hpp
+++ b/luprex/core/cpp/world.hpp
@@ -194,7 +194,7 @@ public:
 
     // Run all unit tests.
     //
-    void run_unittests() { source_db_.run_unittests(); }
+    void run_unittests();
     
     // fetch_global_pointer
     //
@@ -263,6 +263,10 @@ private:
     //
     void invoke_lua(int64_t actor_id, int64_t place_id, const std::string &action, const InvocationData &data);
     
+    // Invoke the flush-prints operation.
+    //
+    void invoke_flush_prints(int64_t actor_id, int64_t place_id, const std::string &action, const InvocationData &data);
+    
 public:
     ////////////////////////////////////////////////////////////////////////////
     //
diff --git a/luprex/core/lua/ut-table.lua b/luprex/core/lua/ut-table.lua
index bf8e48f6..6831d98f 100644
--- a/luprex/core/lua/ut-table.lua
+++ b/luprex/core/lua/ut-table.lua
@@ -1,12 +1,6 @@
 
 makeclass("unittests")
 
-function cmt()
-    for i=1,100000 do
-        local t = {1,2,3,4,5,a=1,b=2,c=3,d=4,e=5}
-        table.clear(t)
-    end
-end
 
 function unittests.tables()
     -- check table.count
@@ -16,7 +10,7 @@ function unittests.tables()
 
     -- check table.clear
     local t = { a = 1, b = 2 }
-    table.clear(t)
+    table.clear(t, true)
     assert(t.a == nil)
     assert(t.b == nil)
     assert(table.count(t) == 0)