m_DefineElement it's impossible to guess names of available parameters and their current values. To ease the process
<inp2:m_PrintCurrentParams/> tag can be used, which will output value of each parameter, that is available in current element, e.g.
Unfortunately above mentioned tag fails to render parameter values correctly, when they are not mere text or numbers, but are objects.
Recently I've found new Symfony's VarDumper component (see http://symfony.com/doc/current/components/var_dumper/introduction.html), which is created to deal with that specific problem. It not only uses colors to distinguish each parameter data type, but also can expand/collapse complex data structures if any is present in parameter value.