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varUString

varUString = 258

Example​

function HasNativeUnicodeString(const Value: Variant): Boolean;
begin
  Result := (VarType(Value) and varTypeMask) = varUString;
end;

Usage​

varUString identifies a Velox-managed UnicodeString Variant used by ordinary strings on Velox's current Unicode target.

Additional Technical Info​

varUString is the base TVarType code $0102 for a Delphi-managed UnicodeString. The modified compiler registers it only on Unicode Delphi targets; Velox's current target satisfies that condition, and ordinary script String values normally use this representation when stored in a Variant.

The payload is reference-counted UTF-16 text and is explicitly not an OLE base type. Automation uses varOleStr (BSTR), so crossing that boundary can allocate/copy even though both hold Unicode text.

Text and ownership boundaries

  • Length is measured in UTF-16 code units, not user-perceived characters. A supplementary Unicode character uses a surrogate pair.
  • Embedded null characters are valid in the managed string but can be truncated by null-terminated APIs.
  • Assignment shares reference-counted storage until copy-on-write behavior requires separation; clearing releases a reference.
  • Conversion to/from varString applies a byte-string code page and can lose data.
  • Delphi VarArrayCreate does not accept varUString as a fixed SAFEARRAY element type; use varOleStr or Variant elements.

VarAsType can request varUString for supported values. VarType inspects without formatting or allocation.

The example is source-reviewed only; no Unicode text was allocated or converted.

External references

Created 2026-07-15