IlvAccessor Class Reference

Base class of all dynamic accessors. More...

#include <ilviews/protos/accessor.h>

Inheritance diagram for IlvAccessor:

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. More...
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. More...
const IlSymbol *	getName () const
	Returns the name of the accessor. More...
IlvValueTypeClass *	getType () const
	Returns the type of the accessor. More...
virtual IlBoolean	isOutputAccessor (IlBoolean &inputAndOutput)
	Queries if the accessor is an output accessor. More...
virtual IlBoolean	isOutputValue (const IlSymbol *name) const
	Queries if the accessor is an output accessor. More...
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. More...
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 IlvAccessible::queryValues() for each IlvAccessor attached to the IlvAccessorHolder.
void	setName (const IlSymbol *name)
	Sets the name of the accessor. More...

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 IlvAccessor objects.

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

compareValues()

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 default implementation simply calls the IlvAccessible::compareValues(const IlvAccessible*, IlvValue*, IlUShort, IlvValueArray&) const 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.

Parameters

object	The object to compare.
ref	The reference to compare to.
values	The values to be compared.
count	The number of elements in the array values.
diffs	Where the differences are stored.

Returns

The number of differences found. This is therefore the size of the output array diffs.

See also

IlvAccessible::compareValues().

IlvProtoInstance, IlvPrototype.

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

getAccessors()

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 IlvPrototypeAccessor, IlvMultipleAccessor, and IlvMultipleUserAccessor.

getName()

const IlSymbol* IlvAccessor::getName

(

)

const

Returns the name of the accessor.

Returns

The name of the accessor.

getType()

IlvValueTypeClass* IlvAccessor::getType

(

)

const

Returns the type of the accessor.

Returns

A pointer to the type instance of the accessor.

isOutputAccessor()

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 otherwise.

isOutputValue()

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 otherwise.

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

matchValues()

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 IlvAccessor objects 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 IlvPrototypeAccessor, IlvMultipleAccessor, and IlvMultipleUserAccessor.

setName()

void IlvAccessor::setName

(

const IlSymbol *

name

)

Sets the name of the accessor.

Parameters

name	The new name of the accessor.