pls add syntactic sugars of List and Map

[stategen]

1. add property or getter of selected to List;

2. list?.asMap()?.keys?.map(...) =>list?.asMap().keys.map(...);
   when ?. get null , cade after should stop ;

3. {...map} , map should can be null like javascript?

[leafpetersen]

1. dd property or getter of selected to List;

Not sure what is meant by this, can you elaborate?

2. list?.asMap()?.keys?.map(...) =>list?.asMap().keys.map(...);
when ?. get null , cade after should stop ;

If I understand this request correctly, this is planned for the NNBD release.

3. {...map} , map should can be null like javascript?

You can currently write {...?map} which evaluates to {} if map is null. Is that what you're looking for?

[stategen]

2 & 3, yes!thanks!,
for 1:
List sometimes for render, the item's property of selected of checked is importent. and will save more code.
var list =['aaa','bbb','ccc','ddd'];
list.select(1);
list.select(2);
list.asMap().keys.map((index)=>{
if (list.selected(index)){
...
} else {
...
}
});

[stategen]

can you add these
var list =beans?.list;
4. list??(list.add(1)); //<=== if (list!=null) {list.add(1)};
5.list!!=null?list.add(1) ; //<=== list!!=null?list.add(1):null;

[lrhn]

Dart Lists does not have any notion of elements being "selected". They are plain arrays of values. Selection is a UI concept that is not relevant to most uses of lists in programs. For something like that, you probably want some custom list selection model class which matches your use-case.

Ad 4:

  list?.add(1)

will add 1 to the list if the list is not null.

Not sure what 5. mean. The type of list.add(1) is void, so it's not a good choice for an expression's value.(I also don't recognize the !!= operator).
Maybe list?..add(1) will do what you want. This syntax will be added with the NNBD update as a null-aware cascade. It will evaluate to the value of list, and add 1 if that value is not null.

[stategen]

4. list??(myList.addAll(list)); //<=== if (list!=null) {myList.addAll(list)};
   5.list!=null?myList.addAll(list) ; //<=== list!=null?myList.addAll(list):null;

[lrhn]

There is currently no easy way to take an action if an argument value is not null. We have ?. to take an action if the receiver is not null, but nothing shorter than:

if (list != null) myList.addAll(list);

For addAll, it's possible because it has a neutral element: myList.addAll(list ?? const []).
This performs the call in all cases, but we know that it will do nothing with const [] as argument.
If you really need to not call the function at all, then you still need a conditional to guard it.

The syntax list ?? myList.addAll(list) is already valid and means the opposite of what you want—it calls the function only if list is null.

The unmatched ? (with no :) is interesting, but hard to parse, and will likely be problematic with non-nullable types where you can't just use null as a default value.

[stategen]

thanks!

4. list??(myList.addAll(list)); //<=== if (list!=null) {myList.addAll(list)};
   beacuse of format rules, word if must with {} even there is 1 line(this condition is common) ,so I can not write:
   if (list != null) myList.addAll(list);
   but :
   if (list != null) {
   myList.addAll(list);
   } //three lines

5. must with : is ugly, even do nothing after, javascript ,java,typescript...,dart is new lang