Relevance of typename in namedtuple

Question

from collections import namedtuple  Point = namedtuple('whatsmypurpose',['x','y']) p = Point(11,22) print(p) 

Output:

whatsmypurpose(x=11,y=22) 

What's the relevance/use of 'whatsmypurpose'?

Answer 1

namedtuple() is a factory function for tuple subclasses. Here, 'whatsmypurpose'is the type name. When you create a named tuple, a class with this name (whatsmypurpose) gets created internally.

You can notice this by using the verbose argument like:

Point=namedtuple('whatsmypurpose',['x','y'], verbose=True) 

Also you can try type(p) to verify this.

Answer 2

'whatsmypurpose' gives the new subclass its type name. From the docs:

collections.namedtuple(typename, field_names, verbose=False,rename=False)
Returns a new tuple subclass named typename.

Here is an example:

>>> from collections import namedtuple >>> Foo = namedtuple('Foo', ['a', 'b']) >>> type(Foo) <class 'type'> >>> a = Foo(a = 1, b = 2) >>> a Foo(a=1, b=2) >>> Foo = namedtuple('whatsmypurpose', ['a', 'b']) >>> a = Foo(a = 1, b = 2) >>> a whatsmypurpose(a=1, b=2) >>>  

---

Set the verbose parameter to True and you can see the complete whatsmypurpose class definition.

>>> Foo = namedtuple('whatsmypurpose', ['a', 'b'], verbose=True) from builtins import property as _property, tuple as _tuple from operator import itemgetter as _itemgetter from collections import OrderedDict  class whatsmypurpose(tuple):     'whatsmypurpose(a, b)'      __slots__ = ()      _fields = ('a', 'b')      def __new__(_cls, a, b):         'Create new instance of whatsmypurpose(a, b)'         return _tuple.__new__(_cls, (a, b))      @classmethod     def _make(cls, iterable, new=tuple.__new__, len=len):         'Make a new whatsmypurpose object from a sequence or iterable'         result = new(cls, iterable)         if len(result) != 2:             raise TypeError('Expected 2 arguments, got %d' % len(result))         return result      def _replace(_self, **kwds):         'Return a new whatsmypurpose object replacing specified fields with new values'         result = _self._make(map(kwds.pop, ('a', 'b'), _self))         if kwds:             raise ValueError('Got unexpected field names: %r' % list(kwds))         return result      def __repr__(self):         'Return a nicely formatted representation string'         return self.__class__.__name__ + '(a=%r, b=%r)' % self      def _asdict(self):         'Return a new OrderedDict which maps field names to their values.'         return OrderedDict(zip(self._fields, self))      def __getnewargs__(self):         'Return self as a plain tuple.  Used by copy and pickle.'         return tuple(self)      a = _property(_itemgetter(0), doc='Alias for field number 0')      b = _property(_itemgetter(1), doc='Alias for field number 1')