About reading Python code

[WaterWalk]

On Mar 17, 1:54 pm, Stargaming <stargam... at gmail.com> wrote:
> On Sun, 16 Mar 2008 20:54:01 -0700, WaterWalk wrote:
> > Hello. I wonder what's the effective way of figuring out how a piece of
> > python code works.
>
> If your Python code is well-written, it should be easy figuring out what
> it means by just reading it. For more complex programs, of course, this
> method can fail.
>
> > With C I often find it very useful to be able to run
> > the code in step mode and set breakpoints in a debugger so I can watch
> > how the it executes, how the data change and how the code jumps from one
> > function to another. But with Python, the debugger is a little
> > primitive. The default IDLE doesn't even allow me to set a breakpoint.
> > When the code is long, I am often lost in it.
>
> IDLE is just, well, a batteries-included editor. There are many people
> (me included) who do *not* like it because it's so weak and doesn't have
> any real uses cases if your programs get sufficiently complex (because
> IDLE itself is sufficiently primitive).
>
> You might be interested in *real* debuggers, such as the Python Debugger
> `PDB <http://docs.python.org/lib/module-pdb.html>`_. If you don't find
> its usage obvious, a quick google search just turned up a nice `tutorial
> <http://www.ferg.org/papers/debugging_in_python.html>`_.
>
> You might find the `Python Profilers <http://docs.python.org/lib/
> profile.html>`_ particularly interesting, `profile` for finding out which
> function sucks up the most calls/time, `trace` for more sophisticated
> stuff.
> `pythontracer <http://code.google.com/p/pythontracer/>` sounds like a
> good combination of both.
>
> > So I'm curious how to read code effectively. I agree that python code is
> > clear, but when it becomes long, reading it can still be a hard work.
>
> A common practice is just inserting `print` statements since it's so
> easy. If you think your debugging isn't temporary but could be useful and
> will be enabled every now and then, you could also use the `logging
> module <http://docs.python.org/lib/module-logging.html>`_ with the
> ``DEBUG`` level.
>
> There was a blog post recently about how to do this `generically for
> functions <http://wordaligned.org/articles/echo>`_.
>
> > BTW. I think this problem also exists in other script languages.
>
> FWIW, I think it's particularly easier in scripting languages to
> implement all kinds of tracing (apart from debugging, which is rather
> unpopular in Python) because you have one *extra* level (the interpreter)
> between your machine and your code.
>
> HTH,
> Stargaming

Thanks for your informative reply. I'll try them. I think I need more
practice to familiarize myself with those idioms of Python.