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AddDouble

function AddDouble(const aName: String;
  const aValue: Double): TJSONNumber;

Example​

procedure ScriptEvent(var Value: variant);
var
  Document: TJSONObject;
begin
  Document := TJSONObject.Create;
  try
    Document.AddDouble('amount', 12.5);
    Value := Document.AsString;
  finally
    Document.Free;
  end;
end;

Usage​

AddDouble adds a named binary64 number while exposing the hidden misparented TJSONNumber return type and locale-sensitive JSON output.

Additional Technical Info​

AddDouble constructs TJSONDouble, assigns aName and the binary64 payload, and transfers the node to the receiver. The parent owns the node. The declared result is hidden TJSONNumber, whose PascalScript ancestor is incorrectly registered as TObject rather than TJSONValue; the returned expression therefore exposes no generic JSON properties. Usually ignore the result and reacquire the child through an object/array lookup typed as TJSONValue.

The stored payload is a Delphi Double. Serialization delegates to FloatToStrF(..., ffGeneral, 15, 0). It is limited to 15 significant digits and uses process format settings, so a locale whose decimal separator is a comma can produce invalid JSON or conflict with delimiters. Binary rounding also applies.

No finite-value check exists. NaN or infinity accepted by the script/runtime can serialize as implementation-specific non-JSON tokens. This method therefore does not guarantee RFC-compliant numeric output; validate range, finiteness and the serialized text when exchanging data with strict systems.

The allocated child is mutable and borrowed. Parent deletion, erase/reload or destruction invalidates it. Allocation/assignment/insertion exceptions propagate, and an exception during the final owning-list Add can leak the child because the method has no cleanup guard.

External references

Created 2026-07-15