FdcFieldValueChangingCallback<T> typedef
FdcFieldValueChangingCallback<T> =
FdcFieldValueChangeResult<T> ? Function(FdcFieldValueChangingContext<T> context)
Callback invoked before a proposed field value is committed.
Return null or FdcFieldValueChangeResult.accept to accept the value,
return FdcFieldValueChangeResult.replaceValue to substitute another value,
or return FdcFieldValueChangeResult.cancel to reject the change.
Implementation
typedef FdcFieldValueChangingCallback<T> =
FdcFieldValueChangeResult<T>? Function(
FdcFieldValueChangingContext<T> context,
);