NodeSystemDerivationHandlerInterface Class Reference

#include <nodesystem_derivation.h>

Inheritance diagram for NodeSystemDerivationHandlerInterface:

Detailed Description

A node system derivation handler defines a set of methods to customize the attribute derivation behavior of node systems. Usually you don't have to bother about this because the default handler is sufficient. However some node templates have to specialize the default behavior for the node systems which they instantiate, for example to define a custom constant value computation.

To change the handler of a node system a node template has to call MutableRoot::SetDerivationHandler().

Public Member Functions
MAXON_METHOD Result< Opt< Data > >	DeriveAttributeValue (const Block< const Port > &nesting, const DerivedAttribute &attr) const
MAXON_METHOD Result< Tuple< VALUEMODE, Data > >	ComputeConstantValue (const Port &port) const
MAXON_METHOD Result< Bool >	FilterDerivationConnection (const Port &src, const Port &dst) const

Private Member Functions
	MAXON_INTERFACE (NodeSystemDerivationHandlerInterface, MAXON_REFERENCE_CONST, "net.maxon.node.interface.nodesystemderivationhandler")

Member Function Documentation

MAXON_INTERFACE()

MAXON_INTERFACE ( NodeSystemDerivationHandlerInterface  , MAXON_REFERENCE_CONST  , "net.maxon.node.interface.nodesystemderivationhandler"    )

private

DeriveAttributeValue()

MAXON_METHOD Result<Opt<Data> > DeriveAttributeValue	(	const Block< const Port > &	nesting,
		const DerivedAttribute &	attr
	)		const

Computes the value of the derived attribute attr at the port specified by nesting. This method is called during validation of derived attributes. The default implementation just calls attr.DeriveAttributeValue(), but implementations may override this default behavior.

Parameters

[in]	nesting	The last element of nesting if the port for which the attribute value shall be computed, the previous elements are its enclosing ports up to the top-level port.
[in]	attr	The derived attribute whose value shall be computed.

Returns

The derived attribute value.

ComputeConstantValue()

MAXON_METHOD Result<Tuple<VALUEMODE, Data> > ComputeConstantValue

(

const Port &

port

)

const

Computes the value of the ConstantValue attribute at the given port. This method is called during validation of derived attributes. The default implementation returns VALUEMODE::DYNAMIC to indicate that no constant value can be computed. Implementations may override this default behavior.

Parameters

[in]

port

The port for which the constant value shall be computed.

Returns

The value of the ConstantValue attribute of the port.

FilterDerivationConnection()

MAXON_METHOD Result<Bool> FilterDerivationConnection	(	const Port &	src,
		const Port &	dst
	)		const

Checks if connections from src do dst shall be reported by PortFunctions::GetConnections when the GET_CONNECTIONS_MODE::DERIVATION_FILTER flag is set. This method is called by PortFunctions::GetConnections whenever the source port of a connection has GNODE_FLAGS::DERIVATION_FILTER_SOURCE set, the target port has GNODE_FLAGS::DERIVATION_FILTER_TARGET set and both ports belong to instantiations of the same template. Only if this method returns true the connection will be reported by PortFunctions::GetConnections. This allows to hide connections which aren't needed, for example because they transport constant values.

Parameters

[in]	src	The source port of a connection.
[in]	dst	The target port of a connection.

Returns

True if the connection shall be reported by PortFunctions::GetConnections, false otherwise.