Tech talk on proxies and traits

Tom Van Cutsem tomvc at
Fri Apr 30 15:42:26 PDT 2010


I recently gave a Google tech talk on my joint work with Mark S. Miller on
Harmony proxies and the traits.js library. Below is an abstract and a link
to the video.


We discuss two proposed language features for inclusion in
ECMAScript-Harmony. The first, dynamic proxies, enables Javascript
programmers to create proxy objects that can intercept property access,
assignment, enumeration, etc. It is a powerful metaprogramming mechanism
that provides a standard API for creating generic wrappers for transparent
access control, implementing legacy API adaptors, profilers, lazy
initialization, etc.

The second part of the talk introduces a traits library for ECMAScript 5.
Traits are a more robust alternative to multiple inheritance or mixin-based
composition. Based on ECMAScript 5's new "property descriptor" API, we built
a portable lightweight library that supports trait-based object composition.
We discuss the limitations of introducing traits using a library approach
and highlight the benefits of direct support for traits in

Talk slides:
traits.js library:

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