Migrating code that used the Carmenta Engine 4.x C++ API
The section describes some changes in the C++ API in Carmenta Engine 5.
dynamic_ptr_cast<T>
The dynamic_ptr_cast<T>() function has been removed. Use the standard dynamic_cast operator instead. For example:
// Check if a layer is a layerset
bool isLayerSet(const LayerPtr& layer)
{
LayerSetPtr layerSet = dynamic_ptr_cast<LayerSet>(layer);
return layerSet != 0;
}
// Check if a layer is a layerset
bool isLayerSet(const LayerPtr& layer)
{
LayerSetPtr layerSet = dynamic_cast<LayerSet*>(layer.get());
return layerSet != 0;
}
static_cast
The static_cast operator is now safe to use in Carmenta Engine 5. It was not supported in Carmenta Engine 4.x.
// Safe to used static_cast<LayerSet*>(), if operand is guaranteed to be a LayerSet
LayerPtr l = methodReturningALayerSet();
LayerCollectionPtr subLayers = static_cast<LayerSet*>(l.get());
Interface pointers
In Carmenta Engine 4.x, references to interfaces like ICustomOperator or ITool were held as raw C++ pointers. It was up to the application to control the lifetime of these instances. A release() method was later added to the interfaces to simplify this, but it was still difficult to use.
In Carmenta Engine 5, the C++ interfaces have been changed to work with the Ptr smart pointer class. Custom objects implementing these interfaces should always be created with new and managed with the smart pointers, just like any other Carmenta Engine object derived from EngineObject. The lifetime of the custom object will be controlled automatically: when the last reference to the object is removed, the object will be deleted.
// Create a custom operator
ICustomOperatorPtr myOperator = new MyOperator();
CustomOperatorProxyPtr myProxy = new CustomOperatorProxy(myOperator, new AttributeSet());