> I've wanted something like that in Python at different times... thanks!

Python's auto-vivification doens't allow Perl's hap hazard auto-vivification. Perl allows you to say:

    my $foo = {};
    $foo->{'blah'}[0]->{'bar'}++;

And after this statement, $foo will refer a hash which has the structure as accessed in the statement.

I don't think this can be done for a generalized case in Python. Whether I want is a totally different question.

Why is this haphazard? If you don't want reads to change your data structure shape in a well-defined manner, use 'exists' or make an immutable hash with Hash::Util.

I always use http://stackoverflow.com/a/651879/276569

wow thanks i was actually really curious if there was a name for this sort of thing! added a note about it to the gist.

i wonder whether it will be made part of more languages as JSON-esque nested objects proliferate in our code and minds.