Initialize your GWT widgets

I’m a big fan of using GWT to increase web application usability in an incremental fashion. It may be fine to use GWT to build a whole-blown application, but I’ve never done that. When you go the widget approach, often you want to configure the widget, perhaps based on the page it is on. Kevin Jansz talks about how to give a GWT module init params (very much like init-param elements in web.xml). He suggests using the Dictionary class, which is in the i18n module. For a sweet example (that is not even related to i18n), read the Dictionary doc linked to above.There are some caveats. From the aforementioned documentation:

…the Dictionary class is fully dynamic. As a result, a variety of error conditions (particularly those involving key mismatches) cannot be caught until runtime. Similarly, the GWT compiler is unable discard unused dictionary values since the structure cannot be statically analyzed.

To me, using a Dictionary is a better way of getting configuration information from a host page than what I’ve done in the past: write a value to a hidden span and use the DOM GWT class to access it. Much clearer and no unneeded DOM elements. In fact, if you wanted to get fancy, you could generate the javascript object properties dynamically (this is conjecture, I’ve not tested this).

Nice find Kevin!