Wierd template problem.

Submitted by Vandenbroucke Sander on Wed, 2008-05-07 11:24.

Hi,

I have a template wrapper class around RTT::Event:

template<SignatureT>
class MyEvent : public RTT::Event<SignatureT>
{ 

	....
	bool connect(const std::string& Component, const std::string&

Event, boost::function<SignatureT> const& SyncFun);
}

template<typename SignatureT>
bool VDWEvent<SignatureT>::connect(const std::string& Component, const
std::string& Event, boost::function<SignatureT> const& SyncFun)
{ 

	VDWTaskContext* p_comp = VDWTaskContext::nameserver()->

getObject(Component); 

	if(p_comp)
	{
		VDWEvent<SignatureT> event(p_comp->events()->

getEvent<SignatureT>(Event)); 

		event.connect(SyncFun);
	}
	else
	{
		RTT::Logger::In in("VDWEvent::connect");
		RTT::log(RTT::Error) << "Could not connect to event " <<

Event << ", " << "component " << Component << " not
found." << RTT::endlog(); 

		return false;
	}
	return true;

}

When compiling I get an error on line:
VDWEvent<SignatureT>
event(p_comp->events()->getEvent<SignatureT>(Event));

'error: expected primary-expression before '>' token'

I don't have a clue...

In EventService.hpp getEvent is declared as follows:

template<class Signature>
boost::shared_ptr<ActionInterface> getEvent(const std::string& ename)
{ 

	if ( mevents.count(ename) )
      	return mevents[ename];
	return boost::shared_ptr<ActionInterface>();

}

When removing the template<class Signature> all compiles just fine.

Sander.


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Wierd template problem.

Submitted by sspr on Wed, 2008-05-07 11:45.

On Wednesday 07 May 2008 13:24:55 Vandenbroucke Sander wrote:
> Hi,
>
> I have a template wrapper class around RTT::Event:
[...]

>
>
> When compiling I get an error on line:
> VDWEvent<SignatureT>
> event(p_comp->events()->getEvent<SignatureT>(Event));
>
> 'error: expected primary-expression before '>' token'
>
> I don't have a clue...

A classical case of 'typename' omission. You need to write: 

 event(p_comp->events()->getEvent<typename SignatureT>(Event));

The compiler does not 'know' if SignatureT is a type or a value, because it is
passed as a template type. For some really wrong reason 'value' is assumed to
be default, os each time you use SignatureT in a class which depends on that
template parameter, you need to prefix it with 'typename'.

Peter


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Wierd template problem.

Submitted by sspr on Wed, 2008-05-07 11:50.

On Wednesday 07 May 2008 13:40:55 Peter Soetens wrote:
> On Wednesday 07 May 2008 13:24:55 Vandenbroucke Sander wrote:
> > Hi,
> >
> > I have a template wrapper class around RTT::Event:
>
> [...]
>
> > When compiling I get an error on line:
> > VDWEvent<SignatureT>
> > event(p_comp->events()->getEvent<SignatureT>(Event));
> >
> > 'error: expected primary-expression before '>' token'
> >
> > I don't have a clue...
>
> A classical case of 'typename' omission. You need to write:
>
> event(p_comp->events()->getEvent<typename SignatureT>(Event));

And for the type decl as well of course: 

 VDWEvent<typename SignatureT>
 event(p_comp->events()->getEvent<typename SignatureT>(Event));

Peter


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RE: Wierd template problem.

Submitted by Vandenbroucke Sander on Wed, 2008-05-07 13:00.

> >
> > A classical case of 'typename' omission. You need to write:
> >
> > event(p_comp->events()->getEvent<typename SignatureT>(Event));
>
> And for the type decl as well of course:
>
> VDWEvent<typename SignatureT>
> event(p_comp->events()->getEvent<typename SignatureT>(Event));
>
Nope, even more obscure errors.

At least this is compiling:
if(p_comp)
{ 

	RTT::EventService* p_es = p_comp->events();
	VDWEvent<SignatureT> event(p_es->getEvent<SignatureT>(Event));
	event.connect(SyncFun);

}

gcc issue maybe?

Sander.


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