var vm = require('vm');

function myfn() {
    console.log("MYFN");
    console.log("MYFN: a="+ a);
}


var sandbox={console:console, a:42};
var ctx = new vm.createContext(sandbox);

// Evaluates the source code of myfn in the new context
// This will ensure that myfn uses the global context of 'ctx'
vm.runInContext(myfn.toString(), ctx, {filename: "TEST"});

// Retained in the context
console.log(ctx.myfn);

// Use it
vm.runInContext("function okfn() { console.log('OKFN'); console.log('OKFN: a='+a); } console.log('TEST'); console.log('TEST: a='+a);okfn();  myfn();", ctx, {filename:"TEST"});