IlvAccessor Class Reference

Base class of all dynamic accessors. More...

#include <ilviews/protos/accessor.h>

Inheritance diagram for IlvAccessor:

List of all members.

Public Member Functions
	IlvAccessor (const char *name, IlvValueTypeClass *type)
	Creates a new accessor of name name and type type.
virtual IlBoolean	changeValue (IlvAccessorHolder *object, const IlvValue &val)
	Called by the method IlvAccessible::changeValue for each IlvAccessor attached to the IlvAccessorHolder.
virtual IlBoolean	changeValues (IlvAccessorHolder *object, const IlvValue *values, IlUShort count)
	Called by the method IlvAccessible::changeValues for each IlvAccessor attached to the IlvAccessorHolder.
virtual IlUInt	compareValues (const IlvAccessorHolder *object, const IlvAccessible *ref, IlvValue *values, IlUShort count, IlvValueArray &diffs) const
	Compares the values in ref and object and returns the differing values.
virtual void	getAccessors (const IlSymbol *const **accessors, const IlvValueTypeClass *const **types, IlUInt &count) const
	Returns the names and types of the values handled by this accessor.
const IlSymbol *	getName () const
	Returns the name of the accessor.
IlvValueTypeClass *	getType () const
	Returns the type of the accessor.
virtual IlBoolean	isOutputAccessor (IlBoolean &inputAndOutput)
	Queries if the accessor is an output accessor.
virtual IlBoolean	isOutputValue (const IlSymbol *name) const
	Queries if the accessor is an output accessor.
virtual IlShort	matchValues (const IlvAccessorHolder *object, const IlvValue *values, IlUShort count, IlvValue *matchingValues=0) const
	Returns the number of values that are handled by the accessor in the values array of length count.
virtual IlvValue &	queryValue (const IlvAccessorHolder *object, IlvValue &val) const
	Called by the method IlvAccessible::queryValue for each IlvAccessor attached to the IlvAccessorHolder.
virtual void	queryValues (const IlvAccessorHolder *object, IlvValue *values, IlUShort count) const
	Called by the method IlvAccessiblequeryValues for each IlvAccessor attached to the IlvAccessorHolder.
void	setName (const IlSymbol *name)
	Sets the name of the accessor.
Friends
class	IlvAccessorHolder

---

Detailed Description

Base class of all dynamic accessors.

Library: ilvproto

IlvAccessor is the base class of all dynamic accessors in the prototypes library. An IlvAccessor associates a value name, which can be accessed with the changeValue/queryValue interface, with methods that will be called when the value is changed, queried, and compared to another value. An IlvAccessor can be dynamically added to an instance of a subclass of IlvAccessorHolder (most often, an IlvPrototype), which will cause the object to respond to changeValue/queryValue requests for the new value. IlvAccessor provides methods that are similar to those of the IlvAccessible class, except that they have an additional argument, the object for which the accessor is called. IlvAccessorHolder methods call the corresponding methods of IlvAccessor for all accessors attached to the holder. IlvAccessor is subclassed into many specialized classes with particular behaviors. These accessor subclasses provide a simple way of programming the side effects of prototype attributes by combining appropriate IlvAccessors. The most important IlvAccessor subclass is IlvUserAccessor. It provides persistence methods, which make it possible to save accessors to files (in particular, prototype description files). Unless you write new subclasses of IlvGroupNode that define built-in accessors, you will not need to use IlvAccessor subclasses that are not IlvUserAccessor subclasses.

Accessors are base 'bricks' of behavior that hold data (in which case they are called 'attributes') or perform side effects. Therefore, an attribute is a name that can be referenced to store data or perform side effects when a call to changeValue or queryValue is made. An attribute can consist of several accessors, each of them defining part of what the attribute is meant to do.

See also:

IlvAccessible, IlvAccessorHolder, IlvGroupAccessor, IlvGroupNode, IlvMultipleAccessor, IlvProtoInstance, IlvUserAccessor.

---

Member Function Documentation

virtual IlUInt IlvAccessor::compareValues	(	const IlvAccessorHolder *	object,
		const IlvAccessible *	ref,
		IlvValue *	values,
		IlUShort	count,
		IlvValueArray &	diffs
	)			const [virtual]

Compares the values in ref and object and returns the differing values.

Compares the objects object and ref for the values specified by the values array of length count. The differences are stored in the diffs array, and the method returns the number of differences. The default implementation simply calls the IlvAccessible::compareValues method, which will query the values for the two objects and compare them one by one. Subclasses may compare values more cleverly by grouping differences: for example, the IlvGroupAccessor subclass detects when all nodes of a group differ homogeneously and reports only one difference for the whole group.

See also:

IlvAccessible::compareValues, IlvProtoInstance, IlvPrototype.

Reimplemented in IlvGroupAccessor, IlvMultipleGroupAccessor, IlvPrototypeAccessor, IlvUserAccessor, IlvCompositeAccessor, and IlvGroupUserAccessor.

virtual void IlvAccessor::getAccessors	(	const IlSymbol *const **	accessors,
		const IlvValueTypeClass *const **	types,
		IlUInt &	count
	)			const [virtual]

Returns the names and types of the values handled by this accessor.

Returns:

The names and types of the values handled by this accessor. The base class implementation adds only the name and type of this accessor to the accessors and types lists, but subclasses (for example IlvMultipleAccessor) may add several names and types to signal that the accessor can respond to requests for several values.

Reimplemented in IlvMultipleAccessor, IlvPrototypeAccessor, and IlvMultipleUserAccessor.

const IlSymbol* IlvAccessor::getName

(

)

const

Returns the name of the accessor.

Returns:

The name of the accessor.

IlvValueTypeClass* IlvAccessor::getType

(

)

const

Returns the type of the accessor.

Returns:

A pointer to the type instance of the accessor.

virtual IlBoolean IlvAccessor::isOutputAccessor

(

IlBoolean &

inputAndOutput

)

[virtual]

Queries if the accessor is an output accessor.

Parameters:

inputAndOutput

Is set to IlTrue if this accessor is both an input and an output accessor. If this is not the case, inputAndOutput is set to IlFalse when returning from this member function.

Returns:

IlTrue if the accessor is an output accessor, and IlFalse otherwize.

virtual IlBoolean IlvAccessor::isOutputValue

(

const IlSymbol *

name

)

const [virtual]

Queries if the accessor is an output accessor.

Returns:

IlTrue if the accessor is an output accessor, and IlFalse otherwize.

Reimplemented in IlvCallbackAccessor, IlvOutputAccessor, IlvExportOutputAccessor, IlvPrototypeAccessor, and IlvUserAccessor.

virtual IlShort IlvAccessor::matchValues	(	const IlvAccessorHolder *	object,
		const IlvValue *	values,
		IlUShort	count,
		IlvValue *	matchingValues = 0
	)			const [virtual]

Returns the number of values that are handled by the accessor in the values array of length count.

The matching values are copied to the matchingValues array, which must have a length of at least count. This method is called by the changeValue[s]/queryValue[s] methods of the IlvAccessorHolder class to determine which IlvAccessors respond to a request for a set of value names. All the accessors that return a non-null count of matching values will be called by the IlvAccessorHolder, with the matching values as arguments. The base class implementation looks for a value corresponding to the accessor name given in values and copies it to matchingValues. Subclasses of IlvAccessor (for example IlvMultipleAccessor) may match several values.

Reimplemented in IlvMultipleAccessor, IlvPrototypeAccessor, and IlvMultipleUserAccessor.

void IlvAccessor::setName

(

const IlSymbol *

name

)

Sets the name of the accessor.

Parameters:

name

The new name of the accessor.