Add custom function constructor option

README.md

@@ -98,6 +98,7 @@ You should never give end-users unfettered access to the EJS render method, If y
     previously resolved path. Should return an object `{ filename, template }`,
     you may return only one of the properties, where `filename` is the final parsed path and `template`
     is the included content.
+  - `functionClass`         Custom [function constructor](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Function/Function) replacement for a scenario where you would want to add hooks or provide a different execution backend.
 
 This project uses [JSDoc](http://usejsdoc.org/). For the full public API
 documentation, clone the repository and run `jake doc`. This will run JSDoc

lib/ejs.js

@@ -535,6 +535,7 @@ function Template(text, opts) {
   options.async = opts.async;
   options.destructuredLocals = opts.destructuredLocals;
   options.legacyInclude = typeof opts.legacyInclude != 'undefined' ? !!opts.legacyInclude : true;
+  options.functionClass = typeof opts.functionClass === 'function' ? opts.functionClass : undefined;
 
   if (options.strict) {
     options._with = false;
@@ -652,7 +653,9 @@ Template.prototype = {
     }
 
     try {
-      if (opts.async) {
+      if (opts.functionClass !== undefined) {
+        ctor = opts.functionClass;
+      } else if (opts.async) {
         // Have to use generated function for this, since in envs without support,
         // it breaks in parsing
         try {

test/ejs.js

@@ -204,6 +204,15 @@ suite('ejs.compile(str, options)', function () {
     assert.ok(func.name === 'anonymous');
     return done();
   });
+
+  test('allow custom function ctor', function () {
+    var fn = ejs.compile('', {
+      functionClass: function(){
+        return function(){ return 'potato'; }
+      }
+    });
+    assert.equal(fn(), 'potato');
+  });
 });
 
 suite('client mode', function () {