In article <hpa.13cf0000.Just.say.no.to.DOS@ahab.eecs.nwu.edu>
hpa@ahab.eecs.nwu.edu (H. Peter Anvin) writes:

|> An lvalue is a value you can take the address of.

False.  To quote the ARM: "The operand [of operator&] must be a
function, an lvalue, or a qualified-name."  So there are things (like
functions) whose address can be taken which are not l-values.

Even without these exceptions, the above is a circular definition: A
lvalue is something whose address can be take, and to take something's
address, it must be an lvalue.

One thing is certain: the definition of lvalue used in the C standard
cannot simply be taken over into C++.  It just doesn't work.
--
James Kanze      Tel.: (+33) 88 14 49 00     email: kanze@lts.sel.alcatel.de
GABI Software, Sarl., 8 rue des Francs-Bourgeois, F-67000 Strasbourg, France
Conseils en informatique industrielle --
                              -- Beratung in industrieller Datenverarbeitung

In article <rfgCw432B.MGn@netcom.com> rfg@netcom.com (Ronald
F. Guilmette) writes:

|> In article <Cw30u1.LA4@undergrad.math.uwaterloo.ca> cwvernon@undergrad.math.uwaterloo.ca (Vern) writes:
|> >Is the "this" pointer still a valid variable in ANSI C++?

|> Nope.

|> Last I read, it wasn't even an lvalue anymore.  So you can't use it as
|> the left operand of an assignment operator (except perhaps an overloaded
|> user-defined one) and you also can't take its address.

I'm not sure whether it is an l-value (or even what lvalue, as opposed
to rvalue, means with regards to C++), but its type is: "T *const" in
the ARM (and I don't think that this has been changed).  So you cannot
assign to it.

Even in the earliest versions of C++, it wasn't a variable in the
classical sense of the word, since assigning to it had very special
semantics.

And of course, since it is not of class, you cannot define a user
overload for assignment to it, nor for taking its address.
--
James Kanze      Tel.: (+33) 88 14 49 00     email: kanze@lts.sel.alcatel.de
GABI Software, Sarl., 8 rue des Francs-Bourgeois, F-67000 Strasbourg, France
Conseils en informatique industrielle --
                              -- Beratung in industrieller Datenverarbeitung

In article <Cw30u1.LA4@undergrad.math.uwaterloo.ca> cwvernon@undergrad.math.uwaterloo.ca (Vern) writes:
>Is the "this" pointer still a valid variable in ANSI C++?

Nope.

Last I read, it wasn't even an lvalue anymore.  So you can't use it as
the left operand of an assignment operator (except perhaps an overloaded
user-defined one) and you also can't take its address.

--

-- Ron Guilmette, Sunnyvale, CA ---------- RG Consulting -------------------
---- domain addr: rfg@netcom.com ----------- Purveyors of Compiler Test ----
---- uucp addr: ...!uunet!netcom!rfg ------- Suites and Bullet-Proof Shoes -

Is the "this" pointer still a valid variable in ANSI C++?


--
  Never trouble trouble 'til trouble troubles you.