Sunday, September 30, 2012

Team Geek Book Review

Team Geek: A Software Developer's Guide to Working Well with Others by Brian W. Fitzpatrick and Ben Collins-Sussman, is a new book published in July 2012. It is written by two Engineers who are thought leaders within Google. They also heavily contributed and led the open source Subversion SVN) project. At the heart of the book is a central theme: Humility, Respect, and Trust (HRT).

The book focuses on the social aspect of software development, team culture, and personal interactions. Although it surrounds a technical field, the book does not dive into any technical jargon. There is no elaboration on the merits of elegant design patterns or database bottle neck optimizations. Through simple stories and anecdotes, the authors mentor the reader through the obstacles of the IT office place. From hairy pointed bosses, to the perfectionist, to the ego maniac, the authors have encountered a variety of situations and offer the reader practical advice. 

Sunday, August 12, 2012

Groovy Closures Do Not Have Access to Private Methods in a Super Class

Recently I came upon a groovy oddity. (At least it is perceived by me to be an oddity). Closures in a groovy class do not have access to a private method if that method is defined in the superclass. This seems odd paired against the fact that regular methods in a super class can access private method defined in the super class


Groovy closures have the same scope access to class member variables and methods as a regular groovy method. In other words, closures are bound to variables in the scope they are defined. See the codehaus link for the official documentation:

This implies that a closure will play by the rules of Object Orientation in the Java language. However, I found that closures do not have access to private methods that are defined in a super class.

The best way to demonstrate is through a short example from Grails. I have used TDD for the example. Note this is a dummy case with no business purpose. Later on I will offer a more reasonable scenario in the business context where I encountered this scenario.

Sunday, May 20, 2012

Grails Dynamic Dropdown

Recently I had a UI requirement where a customer wanted to select values from two separate dropdowns. The value of the first dropdown essentially filtered the values for the second dropdown. Given the financial projects we support are not heavy on UI requirements, I had to do some initial learning and experimentation to yield a good implementation. This blog entry details the how to implement dynamic dropdowns in Grails with ajax and minimal JavaScript.

Example Problem

A contrived for dynamic dropdowns can be described below:

A user would like to select a sports team for a city. The user first selects a value for a dropdown to choose a city. A second dropdown is filtered with the sports teams within that city. An example to clarify:
  • The user selects Dallas as the city in the first dropdown. The second dropdown now displays values: Mavericks, Cowboys and Rangers.
  • The user selects Pittsburgh as the city in the first dropdown. The second dropdown now displays values Steelers, Pirates, and Penguins.

High Level Design in Grails 

Before we get into the details, we can take a step back and describe how we can accomplish a dynamic dropdown in the grails framework.
  • On a gsp page, create a select dropdown with the list of cities.
  • On change of the city dropdown, send an ajax call to the server with a param of the city selected.
  • A controller on the server receives the parameter and looks for teams based on the city selected.
  • Return a template with a new select dropdown for the teams, providing a model with the filtered list of teams.
We will continue below with code snippets. The code was demoed with Grails 2.0.

Domain Objects
The domain objects for this example are quite simple: A City object with a name, and a Team object.