TCustomVariantType.RightPromotion Method

Indicates whether the right argument to a binary operation should be coerced to a different type.

Pascal

function RightPromotion(const V: TVarData; const Operator: TVarOp; out RequiredVarType: TVarType): Boolean; virtual;

C++

virtual __fastcall Boolean RightPromotion(const TVarData V, const TVarOp Operator, TVarType RequiredVarType);

Description

Override RightPromotion to indicate when the right-hand argument for a binary or comparison operation should be implicitly cast to another type before performing the operation. RightPromotion is called when the right-hand System::Variant in a binary or comparison operation is of this System::Variant type.

Note: In operations that involve two custom Variants, the left-hand argument's RightPromotion method is called first. The right-hand argument's LeftPromotion method is then called only if the left-hand argument's RightPromotion method returns false.

V is the TVarData record for the left-hand argument of the operation.

Operator indicates the type of operation. It can be any of the operators in the following table:

Value	Operation
opAdd	addition
opSubtract	subtraction
opMultiply	multiplication
opDivide	floating-point division
opIntDivide	integer division
opModulus	remainder
opShiftRight	right shift
opShiftRight	right shift
opAnd	bitwise and
opOr	bitwise or
opXor	bitwise exclusive or
opCompare	any comparison operation

RequiredVarType returns the System::Variant type code for the type to which the right-hand argument should be cast before performing the operation. If the operation can proceed with the right-hand argument left as-is, RequiredVarType returns the VType field of V.

RightPromotion returns true if the TCustomVariantType descendant can perform the operation (using the BinaryOp, CompareOp, or Compare method) assuming the right-hand argument can be cast to RequiredVarType. It returns false if the TCustomVariantType descendant can't perform the operation.

As implemented in TCustomVariantType, RightPromotion returns the VarType property as RequiredVarType, and returns true.