whenOrNull<TResult extends Object?> method

  1. @optionalTypeArgs
TResult? whenOrNull<TResult extends Object?>({
  1. TResult? system(
    1. String programId,
    2. ParsedSystemInstruction parsed
    )?,
  2. TResult? splToken(
    1. ParsedSplTokenInstruction parsed
    )?,
  3. TResult? memo(
    1. String? memo
    )?,
  4. TResult? unsupported(
    1. String? program
    )?,
})

A variant of when that fallback to returning null

It is equivalent to doing:

switch (sealedClass) {
  case Subclass(:final field):
    return ...;
  case _:
    return null;
}

Implementation

@optionalTypeArgs TResult? whenOrNull<TResult extends Object?>({TResult? Function( String programId,  ParsedSystemInstruction parsed)?  system,TResult? Function( ParsedSplTokenInstruction parsed)?  splToken,TResult? Function(@JsonKey(name: 'parsed')  String? memo)?  memo,TResult? Function( String? program)?  unsupported,}) {final _that = this;
switch (_that) {
case ParsedInstructionSystem() when system != null:
return system(_that.programId,_that.parsed);case ParsedInstructionSplToken() when splToken != null:
return splToken(_that.parsed);case ParsedInstructionMemo() when memo != null:
return memo(_that.memo);case ParsedInstructionUnsupported() when unsupported != null:
return unsupported(_that.program);case _:
  return null;

}
}