Erik Hofman wrote :
> James Turner wrote:
>
> > Basically, I can envisage lots of things the ChangeListener API is
> > perfect for, whether you're observing a value that changes one a week or
> > 50 times a second, but right now those things won't work because some %
> > of the properties don't tell you they've changed. Now, we could always
> > flag some properties as 'immediate' I suppose, but that seems like a
> > hack. There's nothing wrong with the current API, we just ought to make
> > all the property nodes meet the contract it defines, or we need to
> > remove change listeners from the API and have everyone poll / update as
> > you suggest.
>
> Aren't the C++ opperators the perfect place to add this kind of action
> to tied properties?
I had the same idea reading the message from James.
imagine that template (we are not against templates, aren't we ? ;) :
template <class T>
class tied_value
{
public:
tied_value() : node( 0 ) {}
~tied_value() : { untie(); }
tie( SGPropertyNode_ptr n ) { node = n; n->tie( &val ); }
untie() { node = 0; n->untie( &val ); }
T operator=( const T &v ) { val = v; if (node) node->fireChangeListeners(); return
*this; }
operator T() { return val; }
private:
T val;
SGPropertyNode_ptr node;
}
Then replace every tied values with that template :
change :
double xPos;
into :
tied_value<double> xPos;
You get the picture ?
One can use xPos as usual and when the data is changed, listeners are advertised.
( disclaimer : all the above is written from memory and is presumably
incomplete )
Cheers,
-Fred
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