Improve __eq metatag processing.

src/core/org/luaj/vm2/LuaBoolean.java

@@ -70,9 +70,4 @@ public class LuaBoolean extends LuaValue {
 	public LuaValue getmetatable() { 
 		return s_metatable; 
 	}
-	
-	// equality
-	public boolean eq_b( LuaValue val ) {
-		return this == val || (s_metatable!=null && val.isboolean() && LuaValue.eqmtcall(this, val, s_metatable)); 
-	}
 }

src/core/org/luaj/vm2/LuaDouble.java

@@ -75,7 +75,8 @@ public class LuaDouble extends LuaNumber {
 	public boolean equals(Object o) { return o instanceof LuaDouble? ((LuaDouble)o).v == v: false; }
 	
 	// equality w/ metatable processing
-	public boolean eq_b( LuaValue val )   { return val.raweq(v) || (s_metatable!=null && val.type()==TNUMBER && LuaValue.eqmtcall(val, this, s_metatable)); }
+	public LuaValue eq( LuaValue val )        { return val.raweq(v)? TRUE: FALSE; }
+	public boolean eq_b( LuaValue val )       { return val.raweq(v); }
 
 	// equality w/o metatable processing
 	public boolean raweq( LuaValue val )      { return val.raweq(v); }

src/core/org/luaj/vm2/LuaFunction.java

@@ -67,9 +67,4 @@ public class LuaFunction extends LuaValue {
 	public void setfenv(LuaValue env) {
 		this.env = env!=null? env: NIL;
 	}
-	
-	// equality
-	public boolean eq_b( LuaValue val ) {
-		return this == val || (s_metatable!=null && val.isfunction() && LuaValue.eqmtcall(this, val, s_metatable)); 
-	}
 }

src/core/org/luaj/vm2/LuaInteger.java

@@ -105,7 +105,8 @@ public class LuaInteger extends LuaNumber {
 	public boolean equals(Object o) { return o instanceof LuaInteger? ((LuaInteger)o).v == v: false; }
 	
 	// equality w/ metatable processing
-	public boolean eq_b( LuaValue val )   { return val.raweq(v) || (s_metatable!=null && val.type()==TNUMBER && LuaValue.eqmtcall(val, this, s_metatable)); }
+	public LuaValue eq( LuaValue val )    { return val.raweq(v)? TRUE: FALSE; }
+	public boolean eq_b( LuaValue val )   { return val.raweq(v); }
 	
 	// equality w/o metatable processing
 	public boolean raweq( LuaValue val )  { return val.raweq(v); }

src/core/org/luaj/vm2/LuaNil.java

@@ -83,8 +83,4 @@ public class LuaNil extends LuaValue {
 	public Object      optuserdata(Object defval)          { return defval; }
 	public Object      optuserdata(Class c, Object defval) { return defval; }
 	public LuaValue    optvalue(LuaValue defval)           { return defval; }
-	
-	// equality
-	public LuaValue   eq( LuaValue val )      { return this == val? TRUE: FALSE; }
-	public boolean  eq_b( LuaValue val )      { return this == val; } 
 }

src/core/org/luaj/vm2/LuaString.java

@@ -298,17 +298,8 @@ public class LuaString extends LuaValue {
 	}
 
 	// equality w/ metatable processing
-	public boolean eq_b( LuaValue val ) {
+	public LuaValue eq( LuaValue val )    { return val.raweq(this)? TRUE: FALSE; }
-		if ( val.raweq(this) ) return true;
+	public boolean eq_b( LuaValue val )   { return val.raweq(this); }
-		if ( s_metatable == null || val.type()!=TSTRING || s_inmeta) return false;
-		s_inmeta = true;
-		try {
-			return LuaValue.eqmtcall(val, this, s_metatable); 			
-		} finally { 
-			s_inmeta = false;
-		}
-	}
-	private static boolean s_inmeta = false;
 	
 	// equality w/o metatable processing
 	public boolean raweq( LuaValue val ) {

src/core/org/luaj/vm2/LuaTable.java

@@ -577,6 +577,7 @@ public class LuaTable extends LuaValue {
 	}
 	
 	// equality w/ metatable processing
+	public LuaValue eq( LuaValue val ) {  return eq_b(val)? TRUE: FALSE; }
 	public boolean eq_b( LuaValue val )  {
 		if ( this == val ) return true;
 		if ( m_metatable == null || !val.istable() ) return false;

src/core/org/luaj/vm2/LuaThread.java

@@ -242,9 +242,4 @@ public class LuaThread extends LuaValue implements Runnable {
 		}
 		
 	}
-
-	// equality
-	public boolean eq_b( LuaValue val ) {
-		return this == val || (s_metatable!=null && val.isthread() && LuaValue.eqmtcall(this, val, s_metatable)); 
-	}
 }

src/core/org/luaj/vm2/LuaUserdata.java

@@ -105,8 +105,8 @@ public class LuaUserdata extends LuaValue {
 	}
 
 	// equality w/ metatable processing
-	public LuaValue eq( LuaValue val )     { return val.eq_b(this)? TRUE: FALSE; } 
+	public LuaValue eq( LuaValue val )     { return eq_b(val)? TRUE: FALSE; } 
-	public boolean eq_b( LuaUserdata val ) { 
+	public boolean eq_b( LuaValue val ) { 
 		if ( val.raweq(this) ) return true;
 		if ( m_metatable == null || !val.isuserdata() ) return false;
 		LuaValue valmt = val.getmetatable();

src/core/org/luaj/vm2/LuaValue.java

@@ -256,8 +256,8 @@ public class LuaValue extends Varargs {
 	public boolean equals(Object obj)         { return this == obj; } 
 	
 	// arithmetic equality with metatag processing
-	public LuaValue   eq( LuaValue val )      { return eq_b(val)? TRUE: FALSE; }
+	public LuaValue   eq( LuaValue val )      { return this == val? TRUE: FALSE; }
-	public boolean  eq_b( LuaValue val )      { return false; } 
+	public boolean  eq_b( LuaValue val )      { return this == val; } 
 	public LuaValue  neq( LuaValue val )      { return  eq_b(val)? FALSE: TRUE;  }
 	public boolean neq_b( LuaValue val )      { return !eq_b(val); }
 
@@ -273,10 +273,6 @@ public class LuaValue extends Varargs {
 		LuaValue h = lhsmt.rawget(EQ);
 		return h.isnil() || h!=rhsmt.rawget(EQ)? false: h.call(lhs,rhs).toboolean();
 	}
-	public static final boolean eqmtcall(LuaValue lhs, LuaValue rhs, LuaValue sharedmt) {
-		LuaValue h = sharedmt.rawget(EQ);
-		return h.isnil()? false: h.call(lhs,rhs).toboolean();
-	}
 	
 	// arithmetic operators
 	public LuaValue   add( LuaValue rhs )        { return arithmt(ADD,rhs); }

src/core/org/luaj/vm2/lib/BaseLib.java

@@ -303,9 +303,11 @@ public class BaseLib extends OneArgFunction implements ResourceFinder {
 			case 17: { // "tostring", // (e) -> value
 				LuaValue arg = args.checkvalue(1);
 				LuaValue h = arg.metatag(TOSTRING);
-				if ( ! h.isnil() ) return h.call(arg);
+				if ( ! h.isnil() ) 
+					return h.call(arg);
 				LuaValue v = arg.tostring();
-				if ( ! v.isnil() ) return v;
+				if ( ! v.isnil() ) 
+					return v;
 				return valueOf(arg.tojstring());
 			}
 			case 18: { // "tonumber", // (e [,base]) -> value

test/junit/org/luaj/vm2/UnaryBinaryOperatorsTest.java

@@ -235,6 +235,10 @@ public class UnaryBinaryOperatorsTest extends TestCase {
 		LuaValue tbl = new LuaTable();
 		LuaValue tbl2 = new LuaTable();
 		LuaValue tbl3 = new LuaTable();
+		LuaValue uda  = new LuaUserdata(new Object());
+		LuaValue udb  = new LuaUserdata(uda.touserdata());
+		LuaValue uda2 = new LuaUserdata(new Object());
+		LuaValue uda3 = new LuaUserdata(uda.touserdata());
 		LuaValue nilb = LuaValue.valueOf( LuaValue.NIL.toboolean() );
 		LuaValue oneb = LuaValue.valueOf( LuaValue.ONE.toboolean() );
 		assertEquals( LuaValue.FALSE, nilb );
@@ -247,26 +251,30 @@ public class UnaryBinaryOperatorsTest extends TestCase {
 			LuaString.s_metatable = LuaValue.tableOf( new LuaValue[] { LuaValue.EQ, RETURN_NIL, } );
 			tbl.setmetatable(LuaValue.tableOf( new LuaValue[] { LuaValue.EQ, RETURN_NIL, } ));
 			tbl2.setmetatable(LuaValue.tableOf( new LuaValue[] { LuaValue.EQ, RETURN_NIL, } ));
+			uda.setmetatable(LuaValue.tableOf( new LuaValue[] { LuaValue.EQ, RETURN_NIL, } ));
+			udb.setmetatable(uda.getmetatable());
+			uda2.setmetatable(LuaValue.tableOf( new LuaValue[] { LuaValue.EQ, RETURN_NIL, } ));
 			// diff metatag function
 			tbl3.setmetatable(LuaValue.tableOf( new LuaValue[] { LuaValue.EQ, RETURN_ONE, } ));
+			uda3.setmetatable(LuaValue.tableOf( new LuaValue[] { LuaValue.EQ, RETURN_ONE, } ));
 			
-			// same type, same value, does not invoke metatag op
+			// primitive types or same valu do not invoke metatag as per C implementation
 			assertEquals( tru, tru.eq(tru) );
-			assertEquals( tru, tbl.eq(tbl) );
 			assertEquals( tru, one.eq(one) );
-			// same type, different value, same metatag op.  comparabile via metatag op
+			assertEquals( tru, abc.eq(abc) );
-			assertEquals( nilb, tbl.eq(tbl2) );
+			assertEquals( tru, tbl.eq(tbl) );
-			assertEquals( nilb, tbl2.eq(tbl) );
+			assertEquals( tru, uda.eq(uda) );
-			assertEquals( nilb, tru.eq(fal) );
+			assertEquals( tru, uda.eq(udb) );
-			assertEquals( nilb, fal.eq(tru) );
+			assertEquals( fal, tru.eq(fal) );
-			assertEquals( nilb, zer.eq(one) );
+			assertEquals( fal, fal.eq(tru) );
-			assertEquals( nilb, one.eq(zer) );
+			assertEquals( fal, zer.eq(one) );
-			assertEquals( nilb, pi.eq(ee) );
+			assertEquals( fal, one.eq(zer) );
-			assertEquals( nilb, ee.eq(pi) );
+			assertEquals( fal, pi.eq(ee) );
-			assertEquals( nilb, pi.eq(one) );
+			assertEquals( fal, ee.eq(pi) );
-			assertEquals( nilb, one.eq(pi) );
+			assertEquals( fal, pi.eq(one) );
-			assertEquals( nilb, abc.eq(def) );
+			assertEquals( fal, one.eq(pi) );
-			assertEquals( nilb, def.eq(abc) );
+			assertEquals( fal, abc.eq(def) );
+			assertEquals( fal, def.eq(abc) );
 			// different types.  not comparable
 			assertEquals( fal, fal.eq(tbl) );
 			assertEquals( fal, tbl.eq(fal) );
@@ -276,9 +284,20 @@ public class UnaryBinaryOperatorsTest extends TestCase {
 			assertEquals( fal, one.eq(fal) );
 			assertEquals( fal, abc.eq(one) );
 			assertEquals( fal, one.eq(abc) );
+			assertEquals( fal, tbl.eq(uda) );
+			assertEquals( fal, uda.eq(tbl) );
+			// same type, same value, does not invoke metatag op
+			assertEquals( tru, tbl.eq(tbl) );
+			// same type, different value, same metatag op.  comparabile via metatag op
+			assertEquals( nilb, tbl.eq(tbl2) );
+			assertEquals( nilb, tbl2.eq(tbl) );
+			assertEquals( nilb, uda.eq(uda2) );
+			assertEquals( nilb, uda2.eq(uda) );
 			// same type, different metatag ops.  not comparable
 			assertEquals( fal, tbl.eq(tbl3) );
 			assertEquals( fal, tbl3.eq(tbl) );
+			assertEquals( fal, uda.eq(uda3) );
+			assertEquals( fal, uda3.eq(uda) );
 
 			// always use right argument
 			LuaBoolean.s_metatable = LuaValue.tableOf( new LuaValue[] { LuaValue.EQ, RETURN_ONE, } );
@@ -286,26 +305,30 @@ public class UnaryBinaryOperatorsTest extends TestCase {
 			LuaString.s_metatable = LuaValue.tableOf( new LuaValue[] { LuaValue.EQ, RETURN_ONE, } );
 			tbl.setmetatable(LuaValue.tableOf( new LuaValue[] { LuaValue.EQ, RETURN_ONE, } ));
 			tbl2.setmetatable(LuaValue.tableOf( new LuaValue[] { LuaValue.EQ, RETURN_ONE, } ));
+			uda.setmetatable(LuaValue.tableOf( new LuaValue[] { LuaValue.EQ, RETURN_ONE, } ));
+			udb.setmetatable(uda.getmetatable());
+			uda2.setmetatable(LuaValue.tableOf( new LuaValue[] { LuaValue.EQ, RETURN_ONE, } ));
 			// diff metatag function
 			tbl3.setmetatable(LuaValue.tableOf( new LuaValue[] { LuaValue.EQ, RETURN_NIL, } ));
+			uda3.setmetatable(LuaValue.tableOf( new LuaValue[] { LuaValue.EQ, RETURN_NIL, } ));
 			
-			// same type, same value, does not invoke metatag op
+			// primitive types or same value do not invoke metatag as per C implementation
 			assertEquals( tru, tru.eq(tru) );
-			assertEquals( tru, tbl.eq(tbl) );
 			assertEquals( tru, one.eq(one) );
-			// same type, different value, same metatag op.  comparabile via metatag op
+			assertEquals( tru, abc.eq(abc) );
-			assertEquals( oneb, tbl.eq(tbl2) );
+			assertEquals( tru, tbl.eq(tbl) );
-			assertEquals( oneb, tbl2.eq(tbl) );
+			assertEquals( tru, uda.eq(uda) );
-			assertEquals( oneb, tru.eq(fal) );
+			assertEquals( tru, uda.eq(udb) );
-			assertEquals( oneb, fal.eq(tru) );
+			assertEquals( fal, tru.eq(fal) );
-			assertEquals( oneb, zer.eq(one) );
+			assertEquals( fal, fal.eq(tru) );
-			assertEquals( oneb, one.eq(zer) );
+			assertEquals( fal, zer.eq(one) );
-			assertEquals( oneb, pi.eq(ee) );
+			assertEquals( fal, one.eq(zer) );
-			assertEquals( oneb, ee.eq(pi) );
+			assertEquals( fal, pi.eq(ee) );
-			assertEquals( oneb, pi.eq(one) );
+			assertEquals( fal, ee.eq(pi) );
-			assertEquals( oneb, one.eq(pi) );
+			assertEquals( fal, pi.eq(one) );
-			assertEquals( oneb, abc.eq(def) );
+			assertEquals( fal, one.eq(pi) );
-			assertEquals( oneb, def.eq(abc) );
+			assertEquals( fal, abc.eq(def) );
+			assertEquals( fal, def.eq(abc) );
 			// different types.  not comparable
 			assertEquals( fal, fal.eq(tbl) );
 			assertEquals( fal, tbl.eq(fal) );
@@ -315,9 +338,20 @@ public class UnaryBinaryOperatorsTest extends TestCase {
 			assertEquals( fal, one.eq(fal) );
 			assertEquals( fal, abc.eq(one) );
 			assertEquals( fal, one.eq(abc) );
+			assertEquals( fal, tbl.eq(uda) );
+			assertEquals( fal, uda.eq(tbl) );
+			// same type, same value, does not invoke metatag op
+			assertEquals( tru, tbl.eq(tbl) );
+			// same type, different value, same metatag op.  comparabile via metatag op
+			assertEquals( oneb, tbl.eq(tbl2) );
+			assertEquals( oneb, tbl2.eq(tbl) );
+			assertEquals( oneb, uda.eq(uda2) );
+			assertEquals( oneb, uda2.eq(uda) );
 			// same type, different metatag ops.  not comparable
 			assertEquals( fal, tbl.eq(tbl3) );
 			assertEquals( fal, tbl3.eq(tbl) );
+			assertEquals( fal, uda.eq(uda3) );
+			assertEquals( fal, uda3.eq(uda) );
 			
 		} finally { 
 			LuaBoolean.s_metatable = null;

test/lua/metatags.lua

@@ -1,15 +1,15 @@
-print( '---- initial metatables' )
+local anumber,bnumber   = 111,23.45
-local anumber   = 111
+local astring,bstring = "abc","def"
-local aboolean  = false
+local anumstr,bnumstr = tostring(anumber),tostring(bnumber)
-local afunction = function() end
+local aboolean,bboolean  = false,true
-local athread   = coroutine.create( afunction )
+local afunction,bfunction = function() end, function() end
-local atable    = {}
+local athread,bthead = coroutine.create(afunction),coroutine.create(bfunction)
+local atable,btable    = {},{}
 local values = { anumber, aboolean, afunction, athread, atable }
-for i=1,#values do
+local groups 
-	print( debug.getmetatable( values[i] ) )
-end
 local ts = tostring
 local tb,count = {},0
+
 tostring = function(o)
 	local t = type(o)
 	if t~='thread' and t~='function' and t~='table' then return ts(o) end
@@ -21,11 +21,23 @@ tostring = function(o)
 end
 
 local buildop = function(name)
+	return function(a,b)
+		print( 'mt.__'..name..'()', a, b )
+		return '__'..name..'-result'
+	end
+end
+local buildop3 = function(name)
 	return function(a,b,c)
 		print( 'mt.__'..name..'()', a, b, c )
 		return '__'..name..'-result'
 	end
 end
+local buildop1 = function(name)
+	return function(a)
+		print( 'mt.__'..name..'()', a )
+		return '__'..name..'-result'
+	end
+end
 
 local mt = {
 	__call=buildop('call'),
@@ -35,17 +47,12 @@ local mt = {
 	__div=buildop('div'),
 	__pow=buildop('pow'),
 	__mod=buildop('mod'),
-	__unm=buildop('unm'),
+	__unm=buildop1('unm'),
-	__len=buildop('neg'),
+	__len=buildop1('len'),
-	__eq=buildop('eq'),
 	__lt=buildop('lt'),
 	__le=buildop('le'),
-	__tostring=function(a,b)
-		return 'mt.__tostring('..type(a)..','..type(b)..')'
-	end,
-	__metatable={},
 	__index=buildop('index'),
-	__newindex=buildop('newindex'),
+	__newindex=buildop3('newindex'),
 	__concat=buildop('concat'),
 }
 
@@ -56,9 +63,48 @@ ecall = function(pattern, ...)
 	return s,e
 end 
 
+print( '---- __eq same types' )
+local eqmt = { 	__eq=buildop('eq'), }
+groups = { {nil,nil}, {true,false}, {123,456}, {11,5.5}, {afunction,bfunction}, {athread,bthread}, {astring,bstring}, {anumber,anumstr} }
+for i=1,#groups do
+	local a,b = groups[i][1], groups[i][2]
+	local amt,bmt = debug.getmetatable(a),debug.getmetatable(b)
+	print( type(a), type(b), 'before', pcall( function() return a==b end ) )
+	print( type(a), type(b), 'before', pcall( function() return a~=b end ) )
+	print( debug.setmetatable( a, eqmt ) )
+	print( debug.setmetatable( b, eqmt ) )
+	print( type(a), type(b), 'after', pcall( function() return a==b end ) )
+	print( type(a), type(b), 'after', pcall( function() return a~=b end ) )
+	print( debug.setmetatable( a, amt ) )
+	print( debug.setmetatable( b, bmt ) )
+end
+
+print( '---- __eq, tables - should invoke metatag comparison' )
+groups = { {atable,btable} }
+for i=1,#groups do
+	local a,b = groups[i][1], groups[i][2]
+	local amt,bmt = debug.getmetatable(a),debug.getmetatable(b)
+	print( type(a), type(b), 'before', pcall( function() return a==b end ) )
+	print( type(a), type(b), 'before', pcall( function() return a~=b end ) )
+	print( debug.setmetatable( a, eqmt ) )
+	print( debug.setmetatable( b, eqmt ) )
+	print( type(a), type(b), 'after-a', pcall( function() return a==b end ) )
+	print( type(a), type(b), 'after-a', pcall( function() return a~=b end ) )
+	print( debug.setmetatable( a, amt ) )
+	print( debug.setmetatable( b, bmt ) )
+end
+
+
+print( 'nilmt', debug.getmetatable(nil) )
+print( 'boolmt', debug.getmetatable(true) )
+print( 'number', debug.getmetatable(1) )
+print( 'function', debug.getmetatable(afunction) )
+print( 'thread', debug.getmetatable(athread) )
+
 print( '---- __call' )
 for i=1,#values do
 	local a = values[i]
+	local amt = debug.getmetatable(a)
 	print( type(a), 'before', ecall( 'attempt to call', function() return a('a','b') end ) )
 	print( debug.setmetatable( a, mt ) )
 	print( type(a), 'after', pcall( function() return a() end ) )
@@ -66,13 +112,14 @@ for i=1,#values do
 	print( type(a), 'after', pcall( function() return a('a','b') end ) )
 	print( type(a), 'after', pcall( function() return a('a','b','c') end ) )
 	print( type(a), 'after', pcall( function() return a('a','b','c','d') end ) )
-	print( debug.setmetatable( a, nil ) )
+	print( debug.setmetatable( a, amt ) )
 end
 
 print( '---- __add, __sub, __mul, __div, __pow, __mod' )
 local groups = { {aboolean, aboolean}, {aboolean, athread}, {aboolean, afunction}, {aboolean, "abc"}, {aboolean, atable} }
 for i=1,#groups do
 	local a,b = groups[i][1], groups[i][2]
+	local amt,bmt = debug.getmetatable(a),debug.getmetatable(b)
 	print( type(a), type(b), 'before', ecall( 'attempt to perform arithmetic', function() return a+b end ) )
 	print( type(a), type(b), 'before', ecall( 'attempt to perform arithmetic', function() return b+a end ) )
 	print( type(a), type(b), 'before', ecall( 'attempt to perform arithmetic', function() return a-b end ) )
@@ -94,29 +141,33 @@ for i=1,#groups do
 	print( type(a), type(b), 'after', pcall( function() return b^a end ) )
 	print( type(a), type(b), 'after', pcall( function() return a%b end ) )
 	print( type(a), type(b), 'after', pcall( function() return b%a end ) )
-	print( debug.setmetatable( a, nil ) )
+	print( debug.setmetatable( a, amt ) )
+	print( debug.setmetatable( b, bmt ) )
 end
 
 print( '---- __len' )
-values = { aboolean, afunction, athread }
+values = { aboolean, afunction, athread, anumber }
 for i=1,#values do
 	local a = values[i]
+	local amt = debug.getmetatable(a)
 	print( type(a), 'before', ecall( 'attempt to get length of ', function() return #a end ) )
 	print( debug.setmetatable( a, mt ) )
 	print( type(a), 'after', pcall( function() return #a end ) )
-	print( debug.setmetatable( a, nil ) )
+	print( debug.setmetatable( a, amt ) )
 end
-
+-- 
 print( '---- __neg' )
-values = { aboolean, afunction, athread, "abcd", atable }
+values = { aboolean, afunction, athread, "abcd", atable, anumber }
 for i=1,#values do
-	print( type(values[i]), 'before', ecall( 'attempt to get length of ', function() return #values[i] end ) )
+	local a = values[i]
-	print( debug.setmetatable( values[i], mt ) )
+	local amt = debug.getmetatable(a)
-	print( type(values[i]), 'after', pcall( function() return #values[i] end ) )
+	print( type(v), 'before', ecall( 'attempt to perform arithmetic ', function() return -a end ) )
-	print( debug.setmetatable( values[i], nil ) )
+	print( debug.setmetatable( a, mt ) )
+	print( type(v), 'after', pcall( function() return -a end ) )
+	print( debug.setmetatable( a, amt ) )
 end
 
-print( '---- __eq, __lt, __le, same types' )
+print( '---- __lt, __le, same types' )
 local bfunction = function() end
 local bthread = coroutine.create( bfunction )
 local btable = {}
@@ -124,69 +175,59 @@ local groups
 groups = { {true, true}, {true, false}, {afunction, bfunction}, {athread, bthread}, {atable, atable}, {atable, btable} }
 for i=1,#groups do
 	local a,b = groups[i][1], groups[i][2]
-	print( type(a), type(b), 'before', pcall( function() return a==b end ) )
+	local amt,bmt = debug.getmetatable(a),debug.getmetatable(b)
-	print( type(a), type(b), 'before', pcall( function() return a~=b end ) )
 	print( type(a), type(b), 'before', ecall( 'attempt to compare', function() return a<b end ) )
 	print( type(a), type(b), 'before', ecall( 'attempt to compare', function() return a<=b end ) )
 	print( type(a), type(b), 'before', ecall( 'attempt to compare', function() return a>b end ) )
 	print( type(a), type(b), 'before', ecall( 'attempt to compare', function() return a>=b end ) )
 	print( debug.setmetatable( a, mt ) )
 	print( debug.setmetatable( b, mt ) )
-	print( type(a), type(b), 'after', pcall( function() return a==b end ) )
-	print( type(a), type(b), 'after', pcall( function() return a~=b end ) )
 	print( type(a), type(b), 'after', pcall( function() return a<b end ) )
 	print( type(a), type(b), 'after', pcall( function() return a<=b end ) )
 	print( type(a), type(b), 'after', pcall( function() return a>b end ) )
 	print( type(a), type(b), 'after', pcall( function() return a>=b end ) )
-	print( debug.setmetatable( a, nil ) )
+	print( debug.setmetatable( a, amt ) )
-	print( debug.setmetatable( b, nil ) )
+	print( debug.setmetatable( b, bmt ) )
 end
 
-print( '---- __eq, __lt, __le, different types' )
+print( '---- __lt, __le, different types' )
 groups = { {aboolean, athread}, }
 for i=1,#groups do
 	local a,b = groups[i][1], groups[i][2]
-	print( type(a), type(b), 'before', pcall( function() return a==b end ) )
+	local amt,bmt = debug.getmetatable(a),debug.getmetatable(b)
-	print( type(a), type(b), 'before', pcall( function() return a~=b end ) )
 	print( type(a), type(b), 'before', ecall( 'attempt to compare', function() return a<b end ) )
 	print( type(a), type(b), 'before', ecall( 'attempt to compare', function() return a<=b end ) )
 	print( type(a), type(b), 'before', ecall( 'attempt to compare', function() return a>b end ) )
 	print( type(a), type(b), 'before', ecall( 'attempt to compare', function() return a>=b end ) )
 	print( debug.setmetatable( a, mt ) )
 	print( debug.setmetatable( b, mt ) )
-	print( type(a), type(b), 'after-a', pcall( function() return a==b end ) )
-	print( type(a), type(b), 'after-a', pcall( function() return a~=b end ) )
 	print( type(a), type(b), 'after-a', ecall( 'attempt to compare', function() return a<b end ) )
 	print( type(a), type(b), 'after-a', ecall( 'attempt to compare', function() return a<=b end ) )
 	print( type(a), type(b), 'after-a', ecall( 'attempt to compare', function() return a>b end ) )
 	print( type(a), type(b), 'after-a', ecall( 'attempt to compare', function() return a>=b end ) )
-	print( debug.setmetatable( a, nil ) )
+	print( debug.setmetatable( a, amt ) )
-	print( debug.setmetatable( b, nil ) )
+	print( debug.setmetatable( b, bmt ) )
 end
 
 print( '---- __tostring' )
 values = { aboolean, afunction, athread, atable, "abc" }
+local strmt = { __tostring=function(a)
+		return 'mt.__tostring('..type(a)..')'
+	end,
+}
 for i=1,#values do
 	local a = values[i]
-	print( debug.setmetatable( a, mt ) )
+	local amt = debug.getmetatable(a)
+	print( debug.setmetatable( a, strmt ) )
 	print( type(a), 'after', pcall( function() return ts(a) end ) )
-	print( debug.setmetatable( a, nil ) )
+	print( debug.setmetatable( a, amt ) )
-end
-
-print( '---- __metatable' )
-values = { aboolean, afunction, athread, atable, "abc" }
-for i=1,#values do
-	local a = values[i]
-	print( type(a), 'before', pcall( function() return debug.getmetatable(a), getmetatable(a) end ) )
-	print( debug.setmetatable( a, mt ) )
-	print( type(a), 'after', pcall( function() return debug.getmetatable(a), getmetatable(a) end ) )
-	print( debug.setmetatable( a, nil ) )
 end
 
 print( '---- __index, __newindex' )
 values = { aboolean, anumber, afunction, athread }
 for i=1,#values do
 	local a = values[i]
+	local amt = debug.getmetatable(a)
 	print( type(a), 'before', ecall( 'attempt to index', function() return a.foo end ) )
 	print( type(a), 'before', ecall( 'attempt to index', function() return a[123] end ) )
 	print( type(a), 'before', ecall( 'index', function() a.foo = 'bar' end ) )
@@ -198,7 +239,7 @@ for i=1,#values do
 	print( type(a), 'after', pcall( function() a.foo = 'bar' end ) )
 	print( type(a), 'after', pcall( function() a[123] = 'bar' end ) )
 	print( type(a), 'after', ecall( 'attempt to call', function() return a:foo() end ) )
-	print( debug.setmetatable( a, nil ) )
+	print( debug.setmetatable( a, amt ) )
 end
 
 print( '---- __concat' )
@@ -216,6 +257,7 @@ local concatmt = {
 }	
 for i=1,#groups do
 	local a,b = groups[i][1], groups[i][2]
+	local amt,bmt = debug.getmetatable(a),debug.getmetatable(b)
 	print( type(a), type(b), 'before', ecall( 'attempt to concatenate ', function() return a..b end ) )
 	print( type(a), type(b), 'before', ecall( 'attempt to concatenate ', function() return b..a end ) )
 	print( type(a), type(s), type(t), 'before', ecall( 'attempt to concatenate ', function() return a..s..t end ) )
@@ -227,6 +269,18 @@ for i=1,#groups do
 	print( type(a), type(s), type(t), 'before', pcall( function() return a..s..t end ) )
 	print( type(s), type(a), type(t), 'before', ecall( 'attempt to concatenate ', function() return s..a..t end ) )
 	print( type(s), type(t), type(a), 'before', ecall( 'attempt to concatenate ', function() return s..t..a end ) )
-	print( debug.setmetatable( a, nil ) )
+	print( debug.setmetatable( a, amt ) )
+	print( debug.setmetatable( b, bmt ) )
 end
 
+print( '---- __metatable' )
+values = { aboolean, afunction, athread, atable, "abc" }
+local mtmt = { 	__metatable={}, }
+for i=1,#values do
+	local a = values[i]
+	local amt = debug.getmetatable(a)
+	print( type(a), 'before', pcall( function() return debug.getmetatable(a), getmetatable(a) end ) )
+	print( debug.setmetatable( a, mtmt ) )
+	print( type(a), 'after', pcall( function() return debug.getmetatable(a), getmetatable(a) end ) )
+	print( debug.setmetatable( a, amt ) )
+end