Debugging Ruby/Python/Groovy

Question

I'm rephrasing this question because it was either too uninteresting or too incomprehensible. :)

The original question came about because I'm making the transation from Java to Groovy, but the example could apply equally when transitioning to any of the higher-level languages (Ruby, Python, Groovy).

Java is easy to debug because there is a clear relationship between lines of code, and fairly fine-grained behaviour, e.g. manipulate an array using a for loop:

for ( int i=0; i < array1.size(); i++ )
{
    if ( meetsSomeCriterion(array1.elementAt(i) )
    {
        array2.add( array1.elementAt(i) );
    }   
}

so you can set a breakpoint on the test in the loop and see what happens next. (I know there are better ways to write this; it's just to illustrate the point.)

In languages like Ruby the idiomatic style seems to favour higher-level one-liner coding, e.g. from http://rubyquiz.com/quiz113.html

quiz.to_s.reverse.scan(/(?:\d*\.)?\d{1,3}-?/).join(',').reverse

I'm wondering if you can suggest any effective techniques for debugging this, for example if you changed the regular expression ... would you still use the traditional debugger, and step into/over the chained methods? Or is there a better way?

Thanks!

Answer 1

If I were to debug your example, the first thing I would do is break it down into multiple steps. I don't care if it's "pythonic" or "the ruby way" or "tclish" or whatever, code like that can be difficult to debug.

That's not to say I don't write code like that. Once it's been debugged it is sometimes OK to join it all into a single line but I find myself leaning more toward readability and maintainability and less toward writing concise code. If the one-liner approach is genuinely more readable I'll go with it, but if it's not, I don't.