when<TResult extends Object?> method
TResult
when<TResult extends Object?>({})
A switch
-like method, using callbacks.
As opposed to map
, this offers destructuring.
It is equivalent to doing:
switch (sealedClass) {
case Subclass(:final field):
return ...;
case Subclass2(:final field2):
return ...;
}
Implementation
@optionalTypeArgs
TResult when<TResult extends Object?>({
required TResult Function(File file) file,
required TResult Function(String url) network,
}) {
final _that = this;
switch (_that) {
case XXFile():
return file(_that.file);
case XXImage():
return network(_that.url);
}
}