devops day 1

Here's a script from the Groovy book that explains expandos and makes some sense of why you might want to mess with spinning up methods at runtime. - http://groovy.codehaus.org/ExpandoMetaClass+-+Dynamic+Method+Names

The first example might help you pull off some interactive UI.
The second lends to a more fluid api. 
Run that in your console and smoke it.

import org.springframework.web.util.HtmlUtils

class HTMLCodec {

    static encode = { theTarget ->

        HtmlUtils.htmlEscape(theTarget.toString())

    }

    static decode = { theTarget ->

    HtmlUtils.htmlUnescape(theTarget.toString())

    }

}

//So what we do with these classes is to evaluate the convention and add 

//"encodeAsXXX" methods to every object based on the first part of the 

//name of the codec class such as "encodeAsHTML". The pseudo code to achieve this is below:

def classes = [HTMLCodec]

def codecs = classes.findAll { it.name.endsWith('Codec') }

codecs.each { codec ->

    Object.metaClass."encodeAs${codec.name-'Codec'}" = { codec.newInstance().encode(delegate) }

    Object.metaClass."decodeFrom${codec.name-'Codec'}" = { codec.newInstance().decode(delegate) }

}

def html = '<html><body>hello</body></html>'

println '&lt;html&gt;&lt;body&gt;hello&lt;/body&gt;&lt;/html&gt;' == HtmlUtils.htmlEscape(html)

//vs.

println '&lt;html&gt;&lt;body&gt;hello&lt;/body&gt;&lt;/html&gt;' == html.encodeAsHTML()

println html.encodeAsHTML()