python __str__ for an object

Question

While trying to figure out how BeautifulSoup works, I incidentally learnt the __str__ method (I'm new to python). So if I did not misperceived then the __str__ method helps to shape how the class will be represented if printed out. For instance:

class Foo:     def __str__(self):         return "bar"  >>> x = Foo() >>> print x bar 

Right? So asserting that I'm right, is it possible to override the __str__ method of a list of dictionaries? I mean say that in class Foo you have:

class Foo:    def __init__(self):       self.l = [{"Susan": ("Boyle", 50, "alive")}, {"Albert": ("Speer", 106, "dead")}] 

Now is it possible to have the following outcome?

>>> x = Foo() >>> print x.l "Susan Boyle is 50 and alive. Albert Speer is 106 and dead." 

EDIT

Considering agf's solution, how can I access the dictionary once again? I mean if I define __str__ method then apparently I should define something else to retrieve the dictionary as it is. Please consider the following example:

class PClass(dict):     def __str__(self):         # code to return the result that I want   class Foo:     def __init__(self):         self.l = PClass({"Susan": ["Boyle", ........ })  >>> x = Foo() >>> print x.l  # result that works great >>> y = x.l["Susan"] # this would not work. How can I achieve it?  

Answer 1

You need to subclass the item you're pretty-printing.

from itertools import chain  class PrintableList(list): # for a list of dicts     def __str__(self):         return '. '.join(' '.join(str(x) for x in             chain.from_iterable(zip((item[0], 'is', 'and'), item[1])))                 for item in (item.items()[0] for item in self)) + '.'  class PrintableDict(dict): # for a dict     def __str__(self):         return '. '.join(' '.join(str(x) for x in             chain.from_iterable(zip((item[0], 'is', 'and'), item[1])))                 for item in self.iteritems()) + '.'  class Foo:    def __init__(self):       self.d = PrintableDict({"Susan": ("Boyle", 50, "alive"),                                "Albert": ("Speer", 106, "dead")})  class Bar:    def __init__(self):       self.l = PrintableList([{"Susan": ("Boyle", 50, "alive")},                                {"Albert": ("Speer", 106, "dead")}])  foo = Foo() print self.d bar = Bar() print self.l