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varByRef

varByRef = 16384

Example​

function HasIndirectStorage(const Value: Variant): Boolean;
begin
  Result := (VarType(Value) and varByRef) <> 0;
end;

Usage​

varByRef marks a Variant as an indirect reference whose pointer and referent lifetime are controlled outside the value itself.

Additional Technical Info​

varByRef is the TVarType flag $4000. It means the Variant stores an indirect pointer to a value rather than owning the base payload inline. The flag can be combined with a base code and with varArray.

VarType returns the raw top-level tag, so test this flag directly. Some Delphi predicates call FindVarData and resolve the special varByRef or varVariant wrapper before testing the underlying type. Raw and resolved classifications can therefore be intentionally different.

Lifetime and mutation

  • The referenced storage must remain alive, correctly typed and stable for every read or write. The numeric flag cannot prove any of those conditions.
  • A by-reference Variant may alias data owned by COM, a native caller or another Variant. Changes can be visible outside the script.
  • Copying the wrapper does not necessarily create an independent payload. Do not retain it beyond the callback or API scope that supplied it unless that API explicitly permits retention.
  • Concurrent access is unsafe when the owner can modify, release or rebind the referent.

Velox does not expose a general pointer constructor for scripts. Do not synthesize the tag, combine it with arbitrary numbers or pass it as the requested destination type to VarAsType/VarArrayCreate. Host APIs can legitimately return it, and Delphi's VarArrayRef can create by-reference array wrappers on the native side.

Invalid or expired references can cause more than a normal Variant conversion error, which is why technical flows should copy required values into owned script types promptly.

The example is source-reviewed only; no indirect pointer was dereferenced.

External references

Created 2026-07-15