Object "dumping"

[Andrew Bennetts]

On Mon, Feb 03, 2003 at 11:47:38AM +1000, Derek Thomson wrote:
> Hi all,
> 
> I'm debugging a particularly nasty problem in a moderately complex bit 
> of Python, and I really need something that I can use to just print out 
> the state of an object.
> 
> I also do a lot of Perl, and that's available in Perl with the 
> Data::Dumper module.
> 
> I know Python has pprint, but that stops when it encounters an object 
> ie. it only dumps sequences and hashes, which is less than what I want.

The problem is harder than it seems... simply recursively printing the
objects and their contents won't work for cyclic objects, so for many data
structures, you *need* something that can cope with this, like pickle.

So, if you simply want to dump the objects to a file, and read them back in,
and don't care about human-readability, use pickle.

If you want to read it too, I'd recommend twisted.spread.jelly, from
Twisted.  It's an s-expression based serialisation format that essentially
does the same job as pickle, but is human readable -- particularly if you
run it through pprint <wink>.  I've used it a couple of times for debugging.

There are other pickle alternatives too, like an XMLPickle, iirc.  

-Andrew.