[WHIRR-215] Add builder pattern to addRunUrl() call

• Type: Improvement
• Status: Resolved
• Priority: Minor
• Resolution: Not A Problem
• Affects Version/s: 0.3.0
• Fix Version/s: 0.4.0
• Component/s: core
• Assignee: Lars George
• Reporter: Lars George
• Created: 25/Jan/11 12:48
• Updated: 27/Jan/11 18:48
• Resolved: 27/Jan/11 18:48

Description

If we get optional parameters then the code using varargs gets messy:

String tarurl = clusterSpec.getConfiguration().getString(
  HBaseConstants.KEY_TARBALL_URL);
if (tarurl != null) {
  addRunUrl(event, hbaseInstallRunUrl,
    HBaseConstants.PARAM_PROVIDER, clusterSpec.getProvider(),
    HBaseConstants.PARAM_TARBALL_URL, tarurl);
} else {
  addRunUrl(event, hbaseInstallRunUrl,
    HBaseConstants.PARAM_PROVIDER, clusterSpec.getProvider());
}

We should extend or add a builder pattern so that one can do something like

RunUrl ru = RunUrl.create(event)
  .url(hbaseInstallRunUrl)
  .arg(HBaseConstants.PARAM_PROVIDER, clusterSpec.getProvider());
if (tarUrl != null) {
  st.addArg(HBaseConstants.PARAM_TARBALL_URL, tarurl);
}
addRunUrl(ru);

Or similar to http://stackoverflow.com/questions/3838053/mapmaker-design-pattern referring to the Guava MapMaker class.