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Clone

function Clone: TJSONValue;

Example​

procedure ScriptEvent(var Value: variant);
var
  Source, CopyValue: TJSONValue;
  Text: TJSONString;
begin
  Text := TJSONString.Create;
  CopyValue := nil;
  try
    Source := Text;
    Source.Name := 'status';
    Source.AsString := 'ready';
    CopyValue := Source.Clone;
    Value := CopyValue.AsString;
  finally
    CopyValue.Free;
    Text.Free;
  end;
end;

Usage​

Clone creates a caller-owned same-runtime-class copy of a scalar or complete JSON subtree.

Additional Technical Info​

Clone obtains the receiver's Delphi runtime class, invokes that class's virtual constructor, then calls virtual CopyFrom with the receiver as source. The result therefore has the same actual class, Name, null state and scalar payload. Array and object overrides recursively clone every child in physical order, preserving duplicate names and concrete child classes.

The returned root is a new caller-owned object. Free it in finally. Its descendants are owned by that new root and must not be freed separately. The source is unchanged and shares no owned child objects with a successful container clone.

Cloning a scalar is constant-time apart from managed String copying. Cloning a container is linear in the complete descendant count, recursive, and can temporarily require approximately another tree's memory. Deep nesting can consume significant call stack. The operation has no synchronization; do not mutate the source concurrently.

Construction, allocation and descendant copying exceptions propagate. There is no try..except around the newly constructed result. If CopyFrom raises, the new root is not freed and a partially cloned tree can leak. Use ordinary error handling around untrusted or very large structures; the method offers no transactional or size limit.

The source-reviewed example uses a correctly registered TJSONString. The importer defect on directly constructed TJSONDouble/TJSONInteger expressions means they do not expose this ancestor method.

External references

Created 2026-07-15