RAD Studio VCL Reference
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Indicates whether the right argument to a binary operation should be coerced to a different type.
function RightPromotion(const V: TVarData; const Operator: TVarOp; out RequiredVarType: TVarType): Boolean; virtual;
virtual __fastcall Boolean RightPromotion(const TVarData V, const TVarOp Operator, TVarType RequiredVarType);
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 Variant in a binary or comparison operation is of this Variant type.
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 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.
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