How to say $a=$b->{"A"} ||={} in Python?

[Nick Craig-Wood]

Paul McGuire <ptmcg at austin.rr.com> wrote:
>  Carl Banks' post using defaultdict is the correct solution.  The
>  raison d'etre for defaultdict, and the reason that it is the solution
>  to the OP's question, is that instead of creating a just-in-case
>  default value every time, the defaultdict itself is constructed with a
>  factory method of some kind (in practice, it appears that this factory
>  method is usually the list or dict class constructor).  If a reference
>  to the defaultdict gives a not-yet-existing key, then the factory
>  method is called to construct the new value, that value is stored in
>  the dict with the given key, and the value is passed back to the
>  caller.  No instances are created unless they are truly required for
>  initializing an entry for a never-before-seen key.

I think that if you truly want to emulate a perl hash then you would
want this which does the above but recursively.

from collections import defaultdict

class hash(defaultdict):
    def __init__(self):
        defaultdict.__init__(self, hash)

D=hash()

D[1][2][3][4]=5
D[1][4][5]=6

print D

-- 
Nick Craig-Wood <nick at craig-wood.com> -- http://www.craig-wood.com/nick