How named tuples are implemented internally in python?

Actually, it's very easy to find out how a given namedtuple is implemented: if you pass the keyword argument verbose=True when creating it, its class definition is printed:

>>> Point = namedtuple('Point', "x y", verbose=True) from builtins import property as _property, tuple as _tuple from operator import itemgetter as _itemgetter from collections import OrderedDict class Point(tuple): 'Point(x, y)' __slots__ = () _fields = ('x', 'y') def __new__(_cls, x, y): 'Create new instance of Point(x, y)' return _tuple.__new__(_cls, (x, y)) @classmethod def _make(cls, iterable, new=tuple.__new__, len=len): 'Make a new Point 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 Point object replacing specified fields with new values' result = _self._make(map(kwds.pop, ('x', 'y'), _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__ + '(x=%r, y=%r)' % self @property def __dict__(self): 'A new OrderedDict mapping field names to their values' return OrderedDict(zip(self._fields, self)) def _asdict(self): '''Return a new OrderedDict which maps field names to their values. This method is obsolete. Use vars(nt) or nt.__dict__ instead. ''' return self.__dict__ def __getnewargs__(self): 'Return self as a plain tuple. Used by copy and pickle.' return tuple(self) def __getstate__(self): 'Exclude the OrderedDict from pickling' return None x = _property(_itemgetter(0), doc='Alias for field number 0') y = _property(_itemgetter(1), doc='Alias for field number 1') 

So, it's a subclass of tuple with some extra methods to give it the required behaviour, a _fields class-level constant containing the field names, and property methods for attribute access to the tuple's members.

As for the code behind actually building this class definition, that's deep magic.