CORBA style was: [omniORB] CORBA::string_alloc(len) problem

[Bjorn Wennberg]

"Mark D. Landry" <mdlandry@lincoln.midcoast.com> writes:

> Is there any wonder why developers swear off C++ and CORBA for more
> accessible technologies like Java and VB? You'd need a friggin' master's
> degree in CS to understand this discussion. I've got one and it still
> doesn't make much sense. What ever happened to the art of writing code that
> others can read (and compilers can translate)?
> 
> Sorry, I know this is off topic for this group but unless CORBA becomes more
> usable by the typical business programmer it will fade into the sunset like
> so many other good technologies. One look at a mesage like this and most
> programmers' eyes glaze over. This may explain why we see so many
> unsubscribe messsages sent to the list.;-)
> 
> (Bruce, no offense intended.)

hehe - and then c++ introduced templates and error-messages with templates :-/

Back to the example of accessing the elements of the String_var;
What is wrong with doing:
String_var SomeString = CORBA::string_alloc(100);
char *ptr = SomeString; // uses the operator char *() to extract the raw _data ptr
                        // but does not copy the string
ptr[0] = 'c';
ptr[1] = '+''
ptr[2] = '+';
ptr[3] = 0;


> 
> Bruce Visscher wrote:
> 
> > Just a nit.
> >
> > Stephen Coy wrote:
> > >
> > > You probably need to do something like:
> > >
> > >     char * myStr = CORBA::string_alloc(100);
> > >     String_var myStrVar = myStr;
> >
> > I assume you meant CORBA::String_var.
> >
> > Please don't do this.  This is copy initialization.  According to the
> > ISO C++ standard this is defined to create a temporary using the
> > converting constructor, CORBA::String_var::String_var(char*), then to
> > invoke the copy constructor from the temporary and finally to invoke the
> > String_var destructor on the temporary.  This winds up doing a strlen on
> > unitialized memory in the copy constructor.
> >
> > Compilers are allowed to optimize away the temporary.  Most will.
> > However, the DEC C++ compiler on the VAX won't (it always does on Alpha
> > VMS;  I assume it does on Tru64 Unix).  Therefore, you will only have
> > problems on certain platforms (maybe just the VAX?).  But if you really
> > want to be portable you should use direct initialization syntax:
> >
> >         CORBA::String_var myStrVar(myStr);
> >
> > I realize there are even examples using copy initialization syntax like
> > the above in the CORBA standard.  IMHO, the (CORBA) standard is wrong.
> >
> > Bruce Visscher