X-Git-Url: http://nitlanguage.org

diff --git a/src/naive_interpreter.nit b/src/naive_interpreter.nit
index 9c866fa..592c90a 100644
--- a/src/naive_interpreter.nit
+++ b/src/naive_interpreter.nit
@@ -20,6 +20,7 @@ module naive_interpreter
 import literal
 import typing
 import auto_super_init
+import frontend
 
 redef class ToolContext
 	# --discover-call-trace
@@ -33,8 +34,8 @@ redef class ToolContext
 end
 
 redef class ModelBuilder
-	# Execute the program from the entry point (Sys::main) of the `mainmodule'
-	# `arguments' are the command-line arguments in order
+	# Execute the program from the entry point (`Sys::main`) of the `mainmodule`
+	# `arguments` are the command-line arguments in order
 	# REQUIRE that:
 	#   1. the AST is fully loaded.
 	#   2. the model is fully built.
@@ -57,12 +58,12 @@ redef class ModelBuilder
 		var mainobj = new MutableInstance(sys_type)
 		interpreter.mainobj = mainobj
 		interpreter.init_instance(mainobj)
-		var initprop = mainmodule.try_get_primitive_method("init", sys_type)
+		var initprop = mainmodule.try_get_primitive_method("init", sys_type.mclass)
 		if initprop != null then
 			interpreter.send(initprop, [mainobj])
 		end
 		interpreter.check_init_instance(mainobj)
-		var mainprop = mainmodule.try_get_primitive_method("main", sys_type)
+		var mainprop = mainmodule.try_get_primitive_method("main", sys_type.mclass)
 		if mainprop != null then
 			interpreter.send(mainprop, [mainobj])
 		end
@@ -102,7 +103,8 @@ private class NaiveInterpreter
 
 	fun force_get_primitive_method(name: String, recv: MType): MMethod
 	do
-		return self.modelbuilder.force_get_primitive_method(self.frame.current_node, name, recv, self.mainmodule)
+		assert recv isa MClassType
+		return self.modelbuilder.force_get_primitive_method(self.frame.current_node, name, recv.mclass, self.mainmodule)
 	end
 
 	# Is a return executed?
@@ -110,11 +112,11 @@ private class NaiveInterpreter
 	var returnmark: nullable Frame = null
 
 	# Is a break executed?
-	# Set this mark to skip the evaluation until a labeled statement catch it with `is_break'
+	# Set this mark to skip the evaluation until a labeled statement catch it with `is_break`
 	var breakmark: nullable EscapeMark = null
 
 	# Is a continue executed?
-	# Set this mark to skip the evaluation until a labeled statement catch it with `is_continue'
+	# Set this mark to skip the evaluation until a labeled statement catch it with `is_continue`
 	var continuemark: nullable EscapeMark = null
 
 	# Is a return or a break or a continue executed?
@@ -126,8 +128,8 @@ private class NaiveInterpreter
 	# Read the value when you catch a mark or reach the end of a method
 	var escapevalue: nullable Instance = null
 
-	# If there is a break and is associated with `escapemark', then return true an clear the mark.
-	# If there is no break or if `escapemark' is null then return false.
+	# If there is a break and is associated with `escapemark`, then return true an clear the mark.
+	# If there is no break or if `escapemark` is null then return false.
 	# Use this function to catch a potential break.
 	fun is_break(escapemark: nullable EscapeMark): Bool
 	do
@@ -139,8 +141,8 @@ private class NaiveInterpreter
 		end
 	end
 
-	# If there is a continue and is associated with `escapemark', then return true an clear the mark.
-	# If there is no continue or if `escapemark' is null then return false.
+	# If there is a continue and is associated with `escapemark`, then return true an clear the mark.
+	# If there is no continue or if `escapemark` is null then return false.
 	# Use this function to catch a potential continue.
 	fun is_continue(escapemark: nullable EscapeMark): Bool
 	do
@@ -152,9 +154,9 @@ private class NaiveInterpreter
 		end
 	end
 
-	# Evaluate `n' as an expression in the current context.
+	# Evaluate `n` as an expression in the current context.
 	# Return the value of the expression.
-	# If `n' cannot be evaluated, then aborts.
+	# If `n` cannot be evaluated, then aborts.
 	fun expr(n: AExpr): nullable Instance
 	do
 		var frame = self.frame
@@ -165,15 +167,21 @@ private class NaiveInterpreter
 		if i == null and not self.is_escaping then
 			n.debug("inconsitance: no value and not escaping.")
 		end
+		var implicit_cast_to = n.implicit_cast_to
+		if implicit_cast_to != null then
+			var mtype = self.unanchor_type(implicit_cast_to)
+			if not self.is_subtype(i.mtype, mtype) then n.fatal(self, "Cast failed")
+		end
+
 		#n.debug("OUT Execute expr: value is {i}")
 		#if not is_subtype(i.mtype, n.mtype.as(not null)) then n.debug("Expected {n.mtype.as(not null)} got {i}")
 		frame.current_node = old
 		return i
 	end
 
-	# Evaluate `n' as a statement in the current context.
-	# Do nothing if `n' is sull.
-	# If `n' cannot be evaluated, then aborts.
+	# Evaluate `n` as a statement in the current context.
+	# Do nothing if `n` is null.
+	# If `n` cannot be evaluated, then aborts.
 	fun stmt(n: nullable AExpr)
 	do
 		if n != null then
@@ -186,46 +194,46 @@ private class NaiveInterpreter
 		end
 	end
 
-	# Map used to store values of nodes that must be evaluated once in the system (AOnceExpr)
+	# Map used to store values of nodes that must be evaluated once in the system (`AOnceExpr`)
 	var onces: Map[ANode, Instance] = new HashMap[ANode, Instance]
 
-	# Return the boolean instance associated with `val'.
+	# Return the boolean instance associated with `val`.
 	fun bool_instance(val: Bool): Instance
 	do
 		if val then return self.true_instance else return self.false_instance
 	end
 
-	# Return the integer instance associated with `val'.
+	# Return the integer instance associated with `val`.
 	fun int_instance(val: Int): Instance
 	do
 		var ic = self.mainmodule.get_primitive_class("Int")
 		return new PrimitiveInstance[Int](ic.mclass_type, val)
 	end
 
-	# Return the char instance associated with `val'.
+	# Return the char instance associated with `val`.
 	fun char_instance(val: Char): Instance
 	do
 		var ic = self.mainmodule.get_primitive_class("Char")
 		return new PrimitiveInstance[Char](ic.mclass_type, val)
 	end
 
-	# Return the float instance associated with `val'.
+	# Return the float instance associated with `val`.
 	fun float_instance(val: Float): Instance
 	do
 		var ic = self.mainmodule.get_primitive_class("Float")
 		return new PrimitiveInstance[Float](ic.mclass_type, val)
 	end
 
-	# The unique intance of the `true' value.
+	# The unique intance of the `true` value.
 	var true_instance: Instance
 
-	# The unique intance of the `false' value.
+	# The unique intance of the `false` value.
 	var false_instance: Instance
 
-	# The unique intance of the `null' value.
+	# The unique intance of the `null` value.
 	var null_instance: Instance
 
-	# Return a new array made of `values'.
+	# Return a new array made of `values`.
 	# The dynamic type of the result is Array[elttype].
 	fun array_instance(values: Array[Instance], elttype: MType): Instance
 	do
@@ -239,7 +247,7 @@ private class NaiveInterpreter
 		return res
 	end
 
-	# Return a new native string initialized with `txt'
+	# Return a new native string initialized with `txt`
 	fun native_string_instance(txt: String): Instance
 	do
 		var val = new Buffer.from(txt)
@@ -290,8 +298,8 @@ private class NaiveInterpreter
 	# Store known method, used to trace methods as thez are reached
 	var discover_call_trace: Set[MMethodDef] = new HashSet[MMethodDef]
 
-	# Execute `mpropdef' for a `args' (where args[0] is the receiver).
-	# Return a falue if `mpropdef' is a function, or null if it is a procedure.
+	# Execute `mpropdef` for a `args` (where `args[0]` is the receiver).
+	# Return a falue if `mpropdef` is a function, or null if it is a procedure.
 	# The call is direct/static. There is no message-seding/late-bindng.
 	fun call(mpropdef: MMethodDef, args: Array[Instance]): nullable Instance
 	do
@@ -335,9 +343,11 @@ private class NaiveInterpreter
 		var mproperty = mpropdef.mproperty
 		if self.modelbuilder.mpropdef2npropdef.has_key(mpropdef) then
 			var npropdef = self.modelbuilder.mpropdef2npropdef[mpropdef]
+			self.parameter_check(npropdef, mpropdef, args)
 			return npropdef.call(self, mpropdef, args)
 		else if mproperty.name == "init" then
 			var nclassdef = self.modelbuilder.mclassdef2nclassdef[mpropdef.mclassdef]
+			self.parameter_check(nclassdef, mpropdef, args)
 			return nclassdef.call(self, mpropdef, args)
 		else
 			fatal("Fatal Error: method {mpropdef} not found in the AST")
@@ -345,6 +355,28 @@ private class NaiveInterpreter
 		end
 	end
 
+	# Generate type checks in the C code to check covariant parameters
+	fun parameter_check(node: ANode, mpropdef: MMethodDef, args: Array[Instance])
+	do
+		var msignature = mpropdef.msignature
+		for i in [0..msignature.arity[ do
+			# skip test for vararg since the array is instantiated with the correct polymorphic type
+			if msignature.vararg_rank == i then continue
+
+			# skip if the cast is not required
+			var origmtype =  mpropdef.mproperty.intro.msignature.mparameters[i].mtype
+			if not origmtype.need_anchor then continue
+
+			# get the parameter type
+			var mtype = msignature.mparameters[i].mtype
+			var anchor = args.first.mtype.as(MClassType)
+			mtype = mtype.anchor_to(self.mainmodule, anchor)
+			if not args[i+1].mtype.is_subtype(self.mainmodule, anchor, mtype) then
+				node.fatal(self, "Cast failed")
+			end
+		end
+	end
+
 	fun call_closure(closure: ClosureInstance, args: Array[Instance]): nullable Instance
 	do
 		var nclosuredef = closure.nclosuredef
@@ -368,8 +400,8 @@ private class NaiveInterpreter
 		return null
 	end
 
-	# Execute `mproperty' for a `args' (where args[0] is the receiver).
-	# Return a falue if `mproperty' is a function, or null if it is a procedure.
+	# Execute `mproperty` for a `args` (where `args[0]` is the receiver).
+	# Return a falue if `mproperty` is a function, or null if it is a procedure.
 	# The call is polimotphic. There is a message-seding/late-bindng according to te receiver (args[0]).
 	fun send(mproperty: MMethod, args: Array[Instance]): nullable Instance
 	do
@@ -385,20 +417,11 @@ private class NaiveInterpreter
 			fatal("Reciever is null")
 			abort
 		end
-		var propdefs = mproperty.lookup_definitions(self.mainmodule, mtype)
-		if propdefs.length > 1 then
-			fatal("NOT YET IMPLEMETED ERROR: Property conflict: {propdefs.join(", ")}")
-			abort
-		end
-		assert propdefs.length == 1 else
-			fatal("Fatal Error: No property '{mproperty}' for '{recv}'")
-			abort
-		end
-		var propdef = propdefs.first
+		var propdef = mproperty.lookup_first_definition(self.mainmodule, mtype)
 		return self.call(propdef, args)
 	end
 
-	# Read the attribute `mproperty' of an instance `recv' and return its value.
+	# Read the attribute `mproperty` of an instance `recv` and return its value.
 	# If the attribute in not yet initialized, then aborts with an error message.
 	fun read_attribute(mproperty: MAttribute, recv: Instance): Instance
 	do
@@ -417,8 +440,9 @@ private class NaiveInterpreter
 		if cache.has_key(mtype) then return cache[mtype]
 
 		var res = new Array[AAttrPropdef]
-		for cd in mtype.collect_mclassdefs(self.mainmodule)
-		do
+		var cds = mtype.collect_mclassdefs(self.mainmodule).to_a
+		self.mainmodule.linearize_mclassdefs(cds)
+		for cd in cds do
 			var n = self.modelbuilder.mclassdef2nclassdef[cd]
 			for npropdef in n.n_propdefs do
 				if npropdef isa AAttrPropdef then
@@ -433,8 +457,8 @@ private class NaiveInterpreter
 
 	var collect_attr_propdef_cache = new HashMap[MType, Array[AAttrPropdef]]
 
-	# Fill the initial values of the newly created instance `recv'.
-	# `recv.mtype' is used to know what must be filled.
+	# Fill the initial values of the newly created instance `recv`.
+	# `recv.mtype` is used to know what must be filled.
 	fun init_instance(recv: Instance)
 	do
 		for npropdef in collect_attr_propdef(recv.mtype) do
@@ -442,9 +466,8 @@ private class NaiveInterpreter
 		end
 	end
 
-	# Check that non nullable attributes of `recv' are correctly initialized.
+	# Check that non nullable attributes of `recv` are correctly initialized.
 	# This function is used as the last instruction of a new
-	# FIXME: this will work better once there is nullable types
 	fun check_init_instance(recv: Instance)
 	do
 		if not recv isa MutableInstance then return
@@ -474,7 +497,7 @@ abstract class Instance
 	# else aborts
 	fun is_true: Bool do abort
 
-	# Return true if `self' IS `o' (using the Nit semantic of is)
+	# Return true if `self` IS `o` (using the Nit semantic of is)
 	fun eq_is(o: Instance): Bool do return self is o
 
 	# Human readable object identity "Type#number"
@@ -572,7 +595,7 @@ end
 
 redef class ANode
 	# Aborts the program with a message
-	# `v' is used to know if a colored message is displayed or not
+	# `v` is used to know if a colored message is displayed or not
 	private fun fatal(v: NaiveInterpreter, message: String)
 	do
 		if v.modelbuilder.toolcontext.opt_no_color.value == true then
@@ -587,7 +610,7 @@ redef class ANode
 end
 
 redef class APropdef
-	# Execute a `mpropdef' associated with the current node.
+	# Execute a `mpropdef` associated with the current node.
 	private fun call(v: NaiveInterpreter, mpropdef: MMethodDef, args: Array[Instance]): nullable Instance
 	do
 		fatal(v, "NOT YET IMPLEMENTED method kind {class_name}. {mpropdef}")
@@ -656,11 +679,11 @@ redef class AInternMethPropdef
 			end
 		else if pname == "output_class_name" then
 			var recv = args.first
-			print recv.mtype.as(MClassType).mclass
+			print recv.mtype
 			return null
 		else if pname == "native_class_name" then
 			var recv = args.first
-			var txt = recv.mtype.as(MClassType).mclass.to_s
+			var txt = recv.mtype.to_s
 			return v.native_string_instance(txt)
 		else if pname == "==" then
 			# == is correclt redefined for instances
@@ -730,18 +753,27 @@ redef class AInternMethPropdef
 				return v.int_instance(recv <=> args[1].val.as(Char))
 			end
 		else if cname == "Float" then
+			var recv = args[0].to_f
 			if pname == "unary -" then
-				return v.float_instance(-args[0].to_f)
+				return v.float_instance(-recv)
 			else if pname == "+" then
-				return v.float_instance(args[0].to_f + args[1].to_f)
+				return v.float_instance(recv + args[1].to_f)
 			else if pname == "-" then
-				return v.float_instance(args[0].to_f - args[1].to_f)
+				return v.float_instance(recv - args[1].to_f)
 			else if pname == "*" then
-				return v.float_instance(args[0].to_f * args[1].to_f)
+				return v.float_instance(recv * args[1].to_f)
 			else if pname == "/" then
-				return v.float_instance(args[0].to_f / args[1].to_f)
+				return v.float_instance(recv / args[1].to_f)
+			else if pname == "<" then
+				return v.bool_instance(recv < args[1].to_f)
+			else if pname == ">" then
+				return v.bool_instance(recv > args[1].to_f)
+			else if pname == "<=" then
+				return v.bool_instance(recv <= args[1].to_f)
+			else if pname == ">=" then
+				return v.bool_instance(recv >= args[1].to_f)
 			else if pname == "to_i" then
-				return v.int_instance(args[0].to_f.to_i)
+				return v.int_instance(recv.to_i)
 			end
 		else if cname == "NativeString" then
 			var recvval = args.first.val.as(Buffer)
@@ -804,6 +836,11 @@ redef class AInternMethPropdef
 			mtype = mtype.arguments.first
 			var val = new Array[Instance].filled_with(v.null_instance, args[1].to_i)
 			return new PrimitiveInstance[Array[Instance]](v.mainmodule.get_primitive_class("NativeArray").get_mtype([mtype]), val)
+		else if pname == "native_argc" then
+			return v.int_instance(v.arguments.length)
+		else if pname == "native_argv" then
+			var txt = v.arguments[args[1].to_i]
+			return v.native_string_instance(txt)
 		end
 		fatal(v, "NOT YET IMPLEMENTED intern {mpropdef}")
 		abort
@@ -851,6 +888,8 @@ redef class AExternMethPropdef
 			if pname == "rand" then
 				var res = recvval.rand
 				return v.int_instance(res)
+			else if pname == "native_int_to_s" then
+				return v.native_string_instance(recvval.to_s)
 			end
 		else if cname == "NativeFile" then
 			var recvval = args.first.val
@@ -880,6 +919,8 @@ redef class AExternMethPropdef
 			else if pname == "system" then
 				var res = sys.system(recvval.to_s)
 				return v.int_instance(res)
+			else if pname == "atof" then
+				return v.float_instance(recvval.to_f)
 			end
 		else if cname == "Int" then
 			if pname == "rand" then
@@ -890,6 +931,24 @@ redef class AExternMethPropdef
 				return v.float_instance(args[0].to_f.cos)
 			else if pname == "sin" then
 				return v.float_instance(args[0].to_f.sin)
+			else if pname == "tan" then
+				return v.float_instance(args[0].to_f.tan)
+			else if pname == "acos" then
+				return v.float_instance(args[0].to_f.acos)
+			else if pname == "asin" then
+				return v.float_instance(args[0].to_f.asin)
+			else if pname == "atan" then
+				return v.float_instance(args[0].to_f.atan)
+			else if pname == "sqrt" then
+				return v.float_instance(args[0].to_f.sqrt)
+			else if pname == "exp" then
+				return v.float_instance(args[0].to_f.exp)
+			else if pname == "log" then
+				return v.float_instance(args[0].to_f.log)
+			else if pname == "pow" then
+				return v.float_instance(args[0].to_f.pow(args[1].to_f))
+			else if pname == "rand" then
+				return v.float_instance(args[0].to_f.rand)
 			end
 		else if pname == "native_argc" then
 			return v.int_instance(v.arguments.length)
@@ -898,6 +957,9 @@ redef class AExternMethPropdef
 			return v.native_string_instance(txt)
 		else if pname == "get_time" then
 			return v.int_instance(get_time)
+		else if pname == "srand_from" then
+			srand_from(args[1].to_i)
+			return null
 		else if pname == "atan2" then
 			return v.float_instance(atan2(args[1].to_f, args[2].to_f))
 		else if pname == "pi" then
@@ -931,7 +993,7 @@ redef class AAttrPropdef
 		end
 	end
 
-	# Evaluate and set the default value of the attribute in `recv'
+	# Evaluate and set the default value of the attribute in `recv`
 	private fun init_expr(v: NaiveInterpreter, recv: Instance)
 	do
 		assert recv isa MutableInstance
@@ -947,8 +1009,7 @@ redef class AAttrPropdef
 			return
 		end
 		var mtype = self.mpropdef.static_mtype.as(not null)
-		# TODO The needinit info is statically computed, move it to modelbuilder or whatever
-		mtype = mtype.resolve_for(self.mpropdef.mclassdef.bound_mtype, self.mpropdef.mclassdef.bound_mtype, self.mpropdef.mclassdef.mmodule, true)
+		mtype = mtype.anchor_to(v.mainmodule, recv.mtype.as(MClassType))
 		if mtype isa MNullableType then
 			recv.attributes[self.mpropdef.mproperty] = v.null_instance
 		end
@@ -964,7 +1025,7 @@ redef class ADeferredMethPropdef
 end
 
 redef class AClassdef
-	# Execute an implicit `mpropdef' associated with the current node.
+	# Execute an implicit `mpropdef` associated with the current node.
 	private fun call(v: NaiveInterpreter, mpropdef: MMethodDef, args: Array[Instance]): nullable Instance
 	do
 		var super_inits = self.super_inits
@@ -992,7 +1053,7 @@ end
 redef class AExpr
 	# Evaluate the node as a possible expression.
 	# Return a possible value
-	# NOTE: Do not call this method directly, but use `v.expr'
+	# NOTE: Do not call this method directly, but use `v.expr`
 	# This method is here to be implemented by subclasses.
 	private fun expr(v: NaiveInterpreter): nullable Instance
 	do
@@ -1001,7 +1062,7 @@ redef class AExpr
 	end
 
 	# Evaluate the node as a statement.
-	# NOTE: Do not call this method directly, but use `v.stmt'
+	# NOTE: Do not call this method directly, but use `v.stmt`
 	# This method is here to be implemented by subclasses (no need to return something).
 	private fun stmt(v: NaiveInterpreter)
 	do
@@ -1011,6 +1072,17 @@ redef class AExpr
 end
 
 redef class ABlockExpr
+	redef fun expr(v)
+	do
+		var last = self.n_expr.last
+		for e in self.n_expr do
+			if e == last then break
+			v.stmt(e)
+			if v.is_escaping then return null
+		end
+		return last.expr(v)
+	end
+
 	redef fun stmt(v)
 	do
 		for e in self.n_expr do
@@ -1040,11 +1112,12 @@ redef class AVarExpr
 end
 
 redef class AVarAssignExpr
-	redef fun stmt(v)
+	redef fun expr(v)
 	do
 		var i = v.expr(self.n_value)
-		if i == null then return
+		if i == null then return null
 		v.frame.map[self.variable.as(not null)] = i
+		return i
 	end
 end
 
@@ -1115,6 +1188,17 @@ redef class AAbortExpr
 end
 
 redef class AIfExpr
+	redef fun expr(v)
+	do
+		var cond = v.expr(self.n_expr)
+		if cond == null then return null
+		if cond.is_true then
+			return v.expr(self.n_then.as(not null))
+		else
+			return v.expr(self.n_else.as(not null))
+		end
+	end
+
 	redef fun stmt(v)
 	do
 		var cond = v.expr(self.n_expr)
@@ -1236,6 +1320,16 @@ redef class AOrExpr
 	end
 end
 
+redef class AImpliesExpr
+	redef fun expr(v)
+	do
+		var cond = v.expr(self.n_expr)
+		if cond == null then return null
+		if not cond.is_true then return v.true_instance
+		return v.expr(self.n_expr2)
+	end
+end
+
 redef class AAndExpr
 	redef fun expr(v)
 	do
@@ -1532,12 +1626,7 @@ redef class ASuperExpr
 
 		# stantard call-next-method
 		var mpropdef = v.frame.mpropdef
-		# FIXME: we do not want an ugly static call!
-		var mpropdefs = mpropdef.mproperty.lookup_super_definitions(mpropdef.mclassdef.mmodule, mpropdef.mclassdef.bound_mtype)
-		if mpropdefs.length != 1 then
-			debug("Warning: NOT YET IMPLEMENTED: multiple MPRODFEFS for super {mpropdef} for {recv}: {mpropdefs.join(", ")}")
-		end
-		mpropdef = mpropdefs.first
+		mpropdef = mpropdef.lookup_next_definition(v.mainmodule, recv.mtype)
 		assert mpropdef isa MMethodDef
 		var res = v.call(mpropdef, args)
 		return res
@@ -1572,6 +1661,7 @@ redef class AAttrExpr
 	do
 		var recv = v.expr(self.n_expr)
 		if recv == null then return null
+		if recv.mtype isa MNullType then fatal(v, "Reciever is null")
 		var mproperty = self.mproperty.as(not null)
 		return v.read_attribute(mproperty, recv)
 	end
@@ -1582,6 +1672,7 @@ redef class AAttrAssignExpr
 	do
 		var recv = v.expr(self.n_expr)
 		if recv == null then return
+		if recv.mtype isa MNullType then fatal(v, "Reciever is null")
 		var i = v.expr(self.n_value)
 		if i == null then return
 		var mproperty = self.mproperty.as(not null)
@@ -1595,6 +1686,7 @@ redef class AAttrReassignExpr
 	do
 		var recv = v.expr(self.n_expr)
 		if recv == null then return
+		if recv.mtype isa MNullType then fatal(v, "Reciever is null")
 		var value = v.expr(self.n_value)
 		if value == null then return
 		var mproperty = self.mproperty.as(not null)
@@ -1611,6 +1703,7 @@ redef class AIssetAttrExpr
 	do
 		var recv = v.expr(self.n_expr)
 		if recv == null then return null
+		if recv.mtype isa MNullType then fatal(v, "Reciever is null")
 		var mproperty = self.mproperty.as(not null)
 		assert recv isa MutableInstance
 		return v.bool_instance(recv.attributes.has_key(mproperty))