TCustomVariantType class

In unit Variants

Base class for a custom variant type.

Declaration

pascal

TCustomVariantType = class(TObject)

Inheritance

TCustomVariantType
TObject

Descends from it: TInvokeableVariantType

Description

TCustomVariantType is used as a base class to implement custom variants. To define a custom variant type, a descendent of TCustomVariant must be made, and the appropriate methods must be overridden and implemented according to the specifications of the new type. Typically this means defining how your new type maps to another variant or a basic type.

Note that the TCustomVariantType descendent does not hold the data of the variant: it just describes how a variant record (TVarRec) that contains the new type's data can be examined or manipulated.

Properties

VarType public Registered type.

Methods

`QueryInterface`	protected
`_AddRef`	protected
`_Release`	protected
`SimplisticClear`	protected
`SimplisticCopy`	protected
`RaiseInvalidOp`	protected
`RaiseCastError`	protected
`RaiseDispError`	protected
`LeftPromotion`	protected
`RightPromotion`	protected
`OlePromotion`	protected
`DispInvoke`	protected
`VarDataInit`	protected
`VarDataClear`	protected
`VarDataCopy`	protected
`VarDataCopyNoInd`	protected
`VarDataCast`	protected
`VarDataCastTo`	protected
`VarDataCastToOleStr`	protected
`VarDataFromStr`	protected
`VarDataFromOleStr`	protected
`VarDataToStr`	protected
`VarDataIsEmptyParam`	protected
`VarDataIsByRef`	protected
`VarDataIsArray`	protected
`VarDataIsOrdinal`	protected
`VarDataIsFloat`	protected
`VarDataIsNumeric`	protected
`VarDataIsStr`	protected
`Create`	public	Instantiate a new custom variant type.
`Destroy`	public	Unregister variant type.
`IsClear`	public	Is the custom value unassigned ?
`Cast`	public	Cast a custom variant to another type.
`CastTo`	public	Cast a custom variant to another type.
`CastToOle`	public	Cast variant value to OLE value.
`Clear`	public	Clear a value.
`Copy`	public	Copy a custom variant value.
`BinaryOp`	public	Perform a binary mathematical operation.
`UnaryOp`	public	Perform a unary mathematical operation.
`CompareOp`	public	Check result of a comparison between 2 custom variant values.
`Compare`	public	Comparison 2 custom variant values.

Inherited

From TObject (40)

AfterConstruction BeforeDestruction CheckDisposed ClassInfo ClassName ClassNameIs ClassParent ClassType CleanupInstance DefaultHandler DefaultHandlerStr Dispatch DispatchStr Disposed DisposeOf Equals FieldAddress Free FreeInstance GetDisposed GetHashCode GetInterface GetInterfaceByStr GetInterfaceEntry GetInterfaceEntryByStr GetInterfaceTable GetInterfaceWeak GetLastCastErrorInfo InheritsFrom InitInstance InstanceSize MethodAddress MethodName newinstance QualifiedClassName SafeCallException StringMessageTable SystemHasExtendedRTTI ToString UnitName

An experiment, built from development snapshots. Not the official Free Pascal or Lazarus documentation.