New private names proposal

[Allen Wirfs-Brock]

On Dec 22, 2010, at 11:12 AM, David Flanagan wrote:

> 've now realized that I don't actually object so much to the generative nature of private.  What bugs me is that it essentially declares a meta-identifier that is then used as if it were a regular identifier. It is the meta-mismatch that I have a problem with.

JavaScript already has such "meta identifiers".  But they can't be used as "regular identifiers"  (which I'll interpret as meaning expression contexts), instead they only occur after a dot or on the left hand side of a colon in an object literal.  the private names proposals creates the exact same kind of "meta identifier" for use in the exact same contexts  (and adds a new #. context).  It simply extends the scoping and binding of such meta identifiers.

More explicitly in JavaScript:
var x= new Object;
var obj={x:x};  //same identifier, two different meanings
obj.obj=obj;



> 
> If "private foo" declared a meta identifier <foo>, and I could then write o.<foo>, that would make sense to me.  But of course, that syntax is more cumbersome than just using square brackets.
> 
> It feels to me as if the private declaration is behaving like a macro.
> 
> Are there precedents for this kind of meta-identifier in other languages?

For example, member names in C structs scope to the type that defines them