Question

How do I make a function declared in a closure, global ? This is for a google apps script, hence no window.

There is documentation on how to use closures in google apps scripts, but the example declares an object instead of a function.
http://code.google.com/googleapps/appsscript/articles/appengine.html
var JSON = JSON || {};

// foo = function(){}
(function ()
{
    ...

    foo = function (a, b)
    {
        ...
    }

    foo.prototype =
    {
        ...
    }

    // window.foo = foo; // Not Possible
}());

Answer 1

This should work:

var globalFoo;

(function ()
{
    ...

    foo = function (a, b)
    {
        ...
    }

    foo.prototype =
    {
        ...
    }

    globalFoo = foo;
    // window.foo = foo; // Not Possible
}());

I’ve made a test in a regular html running on the browser and is works fine. Here is the example:

var globalFoo;
console.log("O1")
console.log(globalFoo);

(function(){
    console.log("I1")
    console.log(globalFoo);

    var x = 13;

    var foo = function() {
        console.log('foo caled ' + x);
        x++;
        return true;
    }

    foo();

    globalFoo = foo;

    console.log("I2")
    console.log(globalFoo); 
})();

console.log("O1")
console.log(globalFoo);
console.log(globalFoo());

The firebug output to that is:

O1
undefined
I1
undefined
foo caled 13
I2
function()
O1
function()
foo caled 14
true