Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!tut.cis.ohio-state.edu!rutgers!ucsd!sdcsvax!ucsdhub!hp-sdd!hplabs!hpda!hpwala!hpwale!charlien
From: charlien@hpwale.HP.COM (Charlie Nuzzolo)
Newsgroups: comp.lang.c++
Subject: Re: using references vrs. pointers
Message-ID: <920005@hpwale.HP.COM>
Date: 27 Jan 89 16:31:57 GMT
References: <417@vilya.UUCP>
Organization: HP Waltham Division
Lines: 42


>Thus, I would like to get away from memory pointers in my C++ programs and
>make greater use of references.  However, I seem to have no way of initializing
>a reference to refer to nothing, or testing if it refers to nothing (akin
>to a pointer to NULL).


How about using macros:

   #define NULL_REF(type) *(type*)NULL

   #define IS_NULL_REF(arg) ((void*)&arg == NULL)


Then you can do things like:

   MyClass& obj = NULL_REF(MyClass);

and:

   MyTypedef& myType = NULL_REF(MyTypedef);


You can also pass null references for arguments:

   void myFunction(MyType& t = NULL_REF(MyType))
   {
     if (IS_NULL_REF(t))
	printf("default\n");
     else
	printf("not null default\n");
   }


You can do similar things with class references too but be sure
to use 'const MyClass&' to avoid constructor problems.


Charlie Nuzzolo
Hewlett Packard
(617) 890 6300
charlien@hpwarg.HP.COM