Checking if a variable is a dictionary

[Neil Cerutti]

On Thu, Mar 6, 2008 at 8:06 AM, Guillermo
<guillermo.listas at googlemail.com> wrote:
>  I want to iterate recursively a dictionary whose elements might be
>  strings or nested tuples or dictionaries and then convert values to a
>  tagged format according to some rules.
>
>  d = {'a':"i'm a", 'b':(1,2,3),'c':{'a':"i'm a",'x':"something",'y':
>  ('a','b','c')}}

This could be solved with dynamic polymorphism instead of
introspection, which  might simplify things depending on how your
dictionary is constructed.

class Value(object):
  def to_tagged_format(self):
     raise NotImplementedError

class StringValue(Value):
  def to_tagged_format(self):
    ...

class Tuplevalue(Value):
  def to_tagged_format(self):
    ...
class DictValue(Value):
  def to_tagged_format(self):
    ...


for k, v in d.iteritems():
  d[k] = v.to_tagged_format()

You can also get the dynamic polymorphism without invoking inheritance
by specifying a protocol that the values in your dict must implement,
instead. Protocols are plentiful in Python, perhaps more popular than
type hierarchies.

-- 
Neil Cerutti <mr.cerutti+python at gmail.com>