reduce method return type to type and introduce a single instruction for instance get

lib/ast/basic_expressions.rb

@@ -63,7 +63,18 @@ module Ast
     end
   end
   class AssignmentExpression < Expression
+    #attr_reader  :left, :right
+
     def compile frame , method
+      raise "must assign to NameExpression , not #{left}" unless left.instance_of? NameExpression 
+      r = right.compile(frame,method)
+      frame.compile_set( method , left.name , r )
+    end
+  end
+
+  class VariableExpression < NameExpression
+    def compile frame ,method
+      Virtual::ObjectGet.new(name)
     end
   end
 end

lib/ast/call_site_expression.rb

@@ -53,12 +53,4 @@ module Ast
     end
   end
   
-  class VariableExpression < CallSiteExpression
-#      super( :_get_instance_variable  , [StringExpression.new(name)] )
-    def make_setter 
-      @name = :_set_instance_variable
-      @args << StringExpression.new("value")
-    end
-  end
-  
 end

lib/ast/if_expression.rb

@@ -2,7 +2,9 @@ module Ast
   class IfExpression < Expression
 #    attr_reader  :cond, :if_true, :if_false
     def compile frame , method
-      return nil
+      Virtual::Reference
+    end
+    def old
       f = context.function
       # to execute the logic as the if states it, the blocks are the other way around
       # so we can the jump over the else if true ,and the else joins unconditionally after the true_block

lib/ast/operator_expressions.rb

@@ -2,7 +2,7 @@ module Ast
   class OperatorExpression < Expression
 #    attr_reader  :operator, :left, :right
     def compile frame , method
-      nil
+      Virtual::Reference.new
     end
     def scratch
       into = context.function

lib/ast/return_expression.rb

@@ -2,7 +2,7 @@ module Ast
   class ReturnExpression < Expression
 #    attr_reader  :expression
     def compile frame ,method
-      nil
+      Virtual::Reference.new
     end
     def sc
       into = context.function

lib/ast/while_expression.rb

@@ -2,7 +2,7 @@ module Ast
   class WhileExpression < Expression
 #    attr_reader  :condition, :body
     def compile frame , method
-      nil
+      Virtual::Reference.new
     end
     def old
       into = context.function