AW: [omniORB] fixed-length structs

[Fischer, Clemens]

Hi,

the difference in fixed-length and variable-length structs is that the former ones are returned by value, not by pointer. Yet another of the thousand pitfalls in the IDL to C++ mapping.

In case your get() method is an implemetatation of a CORBA interface method, the correct signature would be DateTime get( <stuff> ). It's also not necessary to create a DateTime instance on the heap. You can simply do it like this:

  DateTime get( <stuff> )
  {
    DateTime ret;
    ret.year = 2007;
    ...
    ret.seconds = 0;
    return ret;
  }

So you don't need the _var type at all. I guess it's only there for symmetry and in case you later want to make the struct variable-length without changing your code.

If you take a look at _CORBA_ConstrType_Fix_Var, you'll notice that it handles its content by value instead of pointer and immediately deletes the value passed as pointer to its contructor.

Kind Regards
Clemens Fischer


-----Ursprüngliche Nachricht-----
Von: omniorb-list-bounces at omniorb-support.com [mailto:omniorb-list-bounces at omniorb-support.com] Im Auftrag von Sean Parker
Gesendet: Mittwoch, 11. Juli 2007 02:08
An: omniorb-list at omniorb-support.com
Betreff: [omniORB] fixed-length structs 

Hello -

  I've encountered an issue simply because I'm trying to
use a struct for the first that is "fixed length" (i.e.
it's a series of longs, w/o a string in it)

  For example, I define a struct:

[Begin IDL]
  struct DateTime
  {
    long year;
    ...
    long seconds;
  };
[End IDL]

  This results in C++ template using the *_Fix_* class (I
forget the exact name) as opposed to the *_Variable_*
template class if the struct had a string in it.

[Begin C++]
  DateTime* get( <stuff> )
  {
    DateTime_var ret = new DateTime();
    ret->year = 2007;
    ...
    ret->seconds = 0;
    return ret._retn();
  }
[End C++]

  Now the compile complains "can't convert DateTime to
DateTime* in return" on return line.
 
 I never had this problem when the template class was for
variable-length structs. Am I doing something wrong?

 Any assistance appreciated.

  Thanks and God Bless
    Sean





God Bless 
    Sean Parker 





       
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