Javascript calling eval on an object literal (with functions)

Question

Disclaimer: I fully understand the risks/downsides of using eval but this is one niche case where I couldn't find any other way.

In Google Apps Scripting, there still is no built-in capability to import a script as a library so many sheets can use the same code; but, there is a facility built-in where I can import text from a plaintext file.

Here's the eval-ing code:

var id = [The-docID-goes-here];
var code = DocsList.getFileById(id).getContentAsString();
var lib = eval(code);
Logger.log(lib.fetchDate());

Here's some example code I'm using in the external file:

{
  fetchDate: function() {
    var d = new Date();
    var dateString = (d.getMonth() + 1) + "/" + d.getDate() + "/" + d.getFullYear();
    return dateString;
  }
}

What I'm aiming for is to drop a big object literal (containing all the library code) onto a local variable so I can reference it's properties/functions like they're contained in their own namespace.