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VarIsEmpty

function VarIsEmpty(const V: Variant): Boolean;

Example​

procedure ScriptEvent(var Value: variant);
var
  Candidate: Variant;
begin
  Candidate := Unassigned;
  Value := VarIsEmpty(Candidate); // True
end;

Usage​

VarIsEmpty tests whether a Variant contains exactly the Empty or Unassigned state.

Parameters and result

ItemTypeDescription
VVariant (const)Value to inspect. Velox resolves nested Variant/by-reference Variant indirection for the predicate.
ResultBooleanTrue only when the resolved stored type is varEmpty; otherwise False.

Additional Technical Info​

VarIsEmpty returns True only when V contains the Variant Empty state represented by varEmpty and normally produced by Unassigned or an uninitialised Variant.

The example is fictional and source-reviewed only.

Implementation and behaviour

The modified PascalScript runtime registers System.Variants.VarIsEmpty directly. Delphi resolves the underlying Variant data and compares its type code with varEmpty; it does not convert or compare the value.

Consequently:

  • Null is not Empty;
  • '', zero and False are not Empty;
  • a nil interface Variant is not Empty, even though VarIsClear can regard it as clear;
  • an allocated array with no meaningful business values is still not Empty; and
  • a custom Variant's clear semantics are not consulted.

Use this predicate when the distinction between never-assigned and explicitly missing/Null is meaningful. Do not use it as a general blank-value test.

Side effects, errors, performance and concurrency

The routine performs a type inspection only. It has no side effects, I/O, allocation or locale dependency and is constant-time apart from following Variant indirection. Normal built-in values do not raise. Concurrent access is safe only while the same underlying Variant is not being changed by another execution context.

Related entries

  • VarIsClear also recognises nil interfaces and custom clear values.
  • VarIsNull recognises the explicit Null state.
  • VarType returns the actual type code rather than a Boolean classification.

External references

Created 2026-07-15