[omniORB] string intialization

[Sai-Lai Lo]

For backward compatiability with C, string constants in C++ are "char *"
and not "const char *" as you might expect. The use of (const char*)"Hello"
to force string copy is defined in the CORBA C++ mapping as the correct
way of assigning string constants to a CORBA string Var or string member.
See "Mapping for Struct Types" in the C++ mapping chapter for details.

Sai-Lai

"Dominic Chorafakis XE41 ext. 9049" <chorafad@access.bel.alcatel.be> writes:

> I have a question about the implementation of the
> class String_member.
> 
> If I define:  typedef sequence?string>  MySeq;
> and in a client I do:
> 
> {
>   MySeq s;
>   s.length(1);
>   s[0] = "Hello";
>   ...
>  }
> 
> the compiler (GNU) interpretes "Hello" as a char *
> (not const char *).
> As a result, the String_member assignment operator
> in CORBA.h
> line 213 is invoked:
> 
> inline String_member? operator= (char *s) {
>   if (_ptr) {
>     string_free(_ptr);
>     _ptr = 0;
>   }
>   _ptr = s;
>   return *this;
> }
> When the variable "MySeq  s"  goes out of scope,
> the destructor of String_member
> invokes string_free to deallocate _ptr , which
> should not be done.
> The problem is solved by doing s[0] = (const char
> *)"Hello", which actually
> allocates a buffer for _ptr and copies the string.
> 
> Is it intentional that the above assignment
> operator just copies the pointer ?  If so,
> should the class String_member not call
> string_free ONLY if it has allocated _ptr
> by a call to string_alloc ?
> 
> Sorry if this topic is already covered in the
> mailing archive but I have some
> problems searching it.

-- 
Dr. Sai-Lai Lo                          |       Research Scientist
                                        |
E-mail:         S.Lo@orl.co.uk          |       Olivetti & Oracle Research Lab
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