721555 - Provide read-only built-in for accessing native constructors

Status: RESOLVED WONTFIX

(Core :: JavaScript Engine, enhancement)

Description

[Alex Vincent [:WeirdAl]]

Lately, there have been a lot of new top-level functions added.  Most of these have names which are not likely to generate collisions (Int32Array, for example).  However, recently a Map and a Set top-level constructor were also added.

As a library developer, I would like to ensure I get the native Map function, and not one which a webpage developer writes.  It's easy for a webpage developer to write:

function Map() {
  // do something
}

and replace the built-in in that scope.

Of course, technically that's his fault, but it's still interfering with my library's function.

Would it be practical to provide a read-only global (BuiltIn) which has these constructors as read-only properties?  I could then call new BuiltIn.Map(), and be assured it's the right thing.

Comment 1

[David Mandelin [:dmandelin]]

Have you checked out Harmony Modules? 

  http://wiki.ecmascript.org/doku.php?id=harmony:modules
  and bug 568953

Modules have static scoping, so your names would not be polluted by anything else. It's part of ES6 and coming to Firefox this year.