bradallen wrote:
Hello,
For container class derived from namedtuple, but which also behaves
like a dictionary by implementing __getitem__ for non-integer index
values, is there a special reserved method which allows intercepting %
string formatting operations? I would like for my container type to
behave appropriately depending on whether the string formatting
operation has a string like this :
"whatever %s yadayada" % mycontainer # needs to act like a tuple
"whatever %(key)s yadayada" % mycontainer # needs to act like a
dictionary
I looked through the Python data model docs at <http://docs.python.org/
reference/datamodel.html#emulating-container-types> but only found
this:
"If the left operand of a % operator is a string or Unicode object, no
coercion takes place and the string formatting operation is invoked
instead."
Thanks!
class toto:
def __getitem__(self, key):
return 'paf'
def __str__(self):
return 'pif'
def toTuple(self):
return (1,2,3)
1/ print '%s %s %s' % toto().toTuple()
'1 2 3'
2/ print '%(key)s ' % toto()
'paf'
3/ print '%s' % toto()
'pif'
1/ I don't know how to spare the explicit toTuple conversion, supporting
tuple() would be tedious
2/ thanks to __getitem__ (duck typing)
3/ thanks to __str__
Anyway why would you want to use the tuple form ? it's beaten in every
aspect by the dictionary form.
JM
"If you need something call me, I'll tell you how to live without it"
(Coluche, about politicians)
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