children 属性
实现
List<Element> get children {
if (_docChildren == null) {
_docChildren = new FilteredElementList(this);
}
return _docChildren!;
}
实现
set children(List<Element> value) {
// Copy list first since we don't want liveness during iteration.
var copy = value.toList();
var children = this.children;
children.clear();
children.addAll(copy);
}