[omniORB] Problem with method definitions

[Perham, David A. (Mission Systems)]

Howdy:
I am using Visual C++ .NET Version 7.1 and building IDL using omniOrb
Version 4.1.0.
In the IDL I decalre an interface with several methods that have as
parameters various combinations of base and complex types. Here is an
example:



boolean RequestCreateEntity( in EntityCreateDataType EntityData,
out long EntityId ) ;
The complex types passed as parameter:
typedef struct EntityCreateData
{
string<100> EntityName ;
string<8> EntityTag ;
short EntityClass ;
ENTITY_CLASSIFICATION_ENUM EntityClassification ;
ENTITY_TYPE_ENUM EntityType ;
boolean EntityActivationStatus ;
ENTITY_CONTROL_FLAG_ENUM EntityControlFlag ;
short EntityXPosition ;
short EntityYPosition ;
short EntityAltitude ;
float EntityCourse ;
short EntitySpeed ;
} EntityCreateDataType ;
In the Implementation class I define this method:
bool RequestCreateEntity(EntityCreateData EntityData,
long EntityId )
{ ... }
When I attempt to build the implementation class I get the following
error on any method which has a structure type (or pointer to such) as a
parameter:
Form1.cpp(270) : error C2259: 'ObjectServerImpl' : cannot instantiate
abstract class
due to following members:
'CORBA::Boolean _impl_EntityInterface::RequestCreateEntity(const
EntityCreateDataType &,CORBA::Long &)' : pure virtual function was not
defined
Looking at the omniOrb generated .h and .cpp files, I can find the
_impl_EntityInterface class with the following definition:
virtual CORBA::Boolean RequestCreateEntity(const EntityCreateDataType&
EntityData, CORBA::Long& EntityId) = 0;
Why does this signature not match the one (I thought) I was creating in
the idl? What am I missing here? Any help would be appreciated.
I have tried changing the parameters and return value of the methods to
CORBA::Long and CORBA::Boolean as well.
Thanks,

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[Luke Deller]

Hi David,

...

Post by Perham, David A. (Mission Systems)
bool RequestCreateEntity(EntityCreateData EntityData,
long EntityId )

...

As you have noticed from the error messages and the generated skeleton
files, the first parameter of your C++ function needs to be of type
"const EntityCreateData &". This is more efficient than
"EntityCreateData" because it doesn't require the whole struct to be
copied when the function is called.

There's a helpful table in the C++ Language Mapping Specification
(version 1.1) which shows the C++ type that you need in your function
signature for different IDL types. It's called "Table 1-3" and is
spread over pages 1-106 and 1-107, in section 1.22.1 "Operation
Parameters and Signatures". You can get this document from here:
http://www.omg.org/technology/documents/formal/c++.htm

Regards,
Luke.
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