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varDispatch

varDispatch = 9

Example​

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

Usage​

varDispatch identifies a reference-counted IDispatch Automation interface whose dynamic property or method access can execute external code.

Additional Technical Info​

varDispatch is the base TVarType code $0009 for an IDispatch Automation interface. The Variant normally owns a reference-counted interface pointer and can support late-bound method/property access.

The type code does not prove that the pointer is non-nil, that a requested member exists, that the server is trusted or that invocation is side-effect free. Automation access may cross process boundaries, display UI, perform network/file/database operations, block, mutate external state or raise dispatch/COM exceptions.

Ownership and use

  • Assignment/copying normally adjusts the interface reference count; clearing releases it. A varByRef form instead depends on external storage lifetime.
  • varUnknown identifies an IUnknown without promising late-bound dispatch. Conversion/querying between the two can fail.
  • A nil interface can still carry an interface type code. Test the operation you require and handle errors rather than relying only on the tag.
  • Do not invoke members derived from untrusted configuration without allow-listing the object and member contract.

VarType reads only the tag and does not invoke the object. Mask the code when flags may be present. Actual late binding uses the current host's Automation support and threading/apartment rules; the Variant constant does not make a server thread-safe.

The example is source-reviewed only; no Automation object was invoked.

External references

Created 2026-07-15