TdxSpreadSheetFunction Type

The procedural type for implementation routines of spreadsheet function signatures.

Declaration

TdxSpreadSheetFunction = procedure(Sender: TdxSpreadSheetFormulaResult; const AParams: TdxSpreadSheetFormulaToken);

Parameters

Name	Type
Sender	TdxSpreadSheetFormulaResult
AParams	TdxSpreadSheetFormulaToken

Remarks

A function signature’s implementation routine:

• Evaluates accepted parameters for possible errors and extracts the parameters from a function call token (via the AParams parameter) in a parsed formula expression.

• Uses the extracted parameters to perform calculations.

• Populates the result token (via the Sender parameter) with one or more calculated results according to the function signature’s ResultKind field value.

The following code example shows how to implement a function that calculates the area of a triangle (S) given two sides (a and b) and the angle (γ, in degrees) between them according to the formula: S = 0.5 * a * b * sin γ.

Delphi

procedure functionTriangleArea(Sender: TdxSpreadSheetFormulaResult; const AParams: TdxSpreadSheetFormulaToken);
var
  P1, P2, P3: Variant;  // The function accepts three numeric parameters
begin
  if(Sender.GetParamsCount(AParams) <> 3) then  // The function has three mandatory parameters
    Sender.SetError(ecValue)  // The function inserts the #VALUE! error code into the result token instead of a calculated value if the parameter count is incorrect
  else
// The function consecutively extracts the three numeric values from a formula call token into the P1, P2, and P3 temporary variables
    if(Sender.ExtractNumericParameter(P1, AParams, 0) and
      Sender.ExtractNumericParameter(P2, AParams, 1) and
      Sender.ExtractNumericParameter(P3, AParams, 2)) then
// The function calculates the area of a triangle if all parameters are successfully extracted as numeric values
      Sender.AddValue(0.5 * P1 * P2 * SIN(P3 * Pi / 180));  // Inserts the calculated result into the result token
end;

C++

void __fastcall functionTriangleArea(TdxSpreadSheetFormulaResult* Sender, const TdxSpreadSheetFormulaToken* AParams)
{
  Variant P1, P2, P3;  // The function accepts three numeric parameters
  if(Sender->GetParamsCount(AParams) != 3)  {  // The function has three mandatory parameters
    Sender->SetError(ecValue);  }  // The function inserts the #VALUE! error code into the result token instead of a calculated value if the parameter count is incorrect
  else {
// The function consecutively extracts the three numeric values from a formula call token into the P1, P2, and P3 temporary variables
    if((Sender->ExtractNumericParameter(P1, AParams)) &&
      (Sender->ExtractNumericParameter(P2, AParams, 1)) &&
      (Sender->ExtractNumericParameter(P3, AParams, 2))) {
// The function calculates the area of a triangle if all parameters are successfully extracted as numeric values
        Sender->AddValue(0.5 * P1 * P2 * P3 * sin(P3 * M_PI / 180));  // Inserts the calculated result into the result token
    }
  }
}

A function signature’s Proc field references the TdxSpreadSheetFunction procedural type.