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VarArraySet

procedure VarArraySet(C: Variant; I: Integer; var S: Variant);

Example​

procedure ScriptEvent(var Value: variant);
var
  Items: Variant;
begin
  Items := VarArrayCreate(2, varVariant);
  VarArraySet('EDI', 0, Items);
  Value := VarArrayGet(Items, 0); // EDI
end;

Usage​

VarArraySet converts and assigns one element in a one-dimensional Variant array.

Parameters

NameTypeDescription
CVariantValue to assign. A fixed-element array converts it to the array's base type.
IIntegerIndex within the array's actual bounds. Velox-created arrays use 0..aLength - 1.
SVariant (var)Existing one-dimensional Variant array to mutate.

Additional Technical Info​

VarArraySet assigns C to the element at index I in Variant array S. It mutates the caller's array and returns no status value; conversion or index failures raise an exception.

The example is fictional and source-reviewed only.

Implementation

The modified PascalScript runtime calls Delphi System.Variants.VarArrayPut(S, C, [I]) with a one-item index list. The compiler also lowers direct assignment syntax such as S[I] := C through this same registered wrapper.

For a fixed-element array, Delphi casts C to the array's base type before writing. For a varVariant array, most Variant values retain their type. Native Delphi string Variants are a special case: they are converted to Automation varOleStr representation before being stored in the SAFEARRAY cell.

Behaviour and errors

  • The public wrapper can address exactly one dimension. A multidimensional array fails because Delphi requires one index per dimension.
  • S must be an actual Variant array. A scalar, Empty or Null value raises a Variant invalid-argument/not-an-array exception.
  • An out-of-range I raises EVariantBadIndexError; no element is selected by wrapping or clamping the index.
  • A value that cannot be converted to a fixed element type raises a Variant type-cast, overflow or range exception. For example, assigning non-numeric text to a varInteger array does not silently produce zero.
  • Assignment replaces the previous managed element and updates its references. If an exception occurs before the SAFEARRAY write, do not assume that a useful conversion result exists.

Side effects, performance and concurrency

The selected cell of S is changed. Fixed-type conversion can allocate temporary string/interface data, and replacing a managed value can release its previous references. A normal indexed write is constant-time apart from conversion and managed-value work.

Do not write the same underlying array concurrently without external synchronisation. Ordinary Delphi Variant assignment copies Variant-array storage, but explicit by-reference Variant representations can still expose shared mutable storage.

Related entries

  • VarArrayCreate chooses the bounds and fixed or mixed element model.
  • VarArrayGet reads a copied element.
  • VarAsType lets a script perform and handle conversion before the write.

External references

Created 2026-07-15