whenOrNull<TResult extends Object?> method

  1. @optionalTypeArgs
TResult? whenOrNull<TResult extends Object?>(
  1. TResult? $default(
    1. String returnTypeName,
    2. String? returnTypeFullLibraryName,
    3. String name,
    4. bool isDeprecated,
    5. bool isExperimental,
    6. List<ExecutableParameterDeclaration> parameters,
    7. List<String> typeParameterNames,
    8. ExecutableType type,
    9. bool isStatic,
    10. Set<String>? entryPoints,
    11. String relativePath,
    )?
)

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 returnTypeName,
          String? returnTypeFullLibraryName,
          String name,
          bool isDeprecated,
          bool isExperimental,
          List<ExecutableParameterDeclaration> parameters,
          List<String> typeParameterNames,
          ExecutableType type,
          bool isStatic,
          Set<String>? entryPoints,
          String relativePath)?
      $default,
) {
  final _that = this;
  switch (_that) {
    case _ExecutableDeclaration() when $default != null:
      return $default(
          _that.returnTypeName,
          _that.returnTypeFullLibraryName,
          _that.name,
          _that.isDeprecated,
          _that.isExperimental,
          _that.parameters,
          _that.typeParameterNames,
          _that.type,
          _that.isStatic,
          _that.entryPoints,
          _that.relativePath);
    case _:
      return null;
  }
}