Factor-out named tuple class definition template strings.
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@ -233,10 +233,58 @@ class OrderedDict(dict):
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### namedtuple
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################################################################################
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_class_template = '''\
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class {typename}(tuple):
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'{typename}({arg_list})'
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__slots__ = ()
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_fields = {field_names!r}
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def __new__(_cls, {arg_list}):
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'Create new instance of {typename}({arg_list})'
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return _tuple.__new__(_cls, ({arg_list}))
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@classmethod
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def _make(cls, iterable, new=tuple.__new__, len=len):
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'Make a new {typename} object from a sequence or iterable'
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result = new(cls, iterable)
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if len(result) != {num_fields:d}:
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raise TypeError('Expected {num_fields:d} arguments, got %d' % len(result))
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return result
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def __repr__(self):
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'Return a nicely formatted representation string'
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return self.__class__.__name__ + '({repr_fmt})' % self
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def _asdict(self):
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'Return a new OrderedDict which maps field names to their values'
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return OrderedDict(zip(self._fields, self))
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def _replace(_self, **kwds):
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'Return a new {typename} object replacing specified fields with new values'
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result = _self._make(map(kwds.pop, {field_names!r}, _self))
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if kwds:
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raise ValueError('Got unexpected field names: %r' % kwds.keys())
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return result
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def __getnewargs__(self):
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'Return self as a plain tuple. Used by copy and pickle.'
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return tuple(self)
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{field_defs}
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'''
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_repr_template = '{name}=%r'
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_field_template = '''\
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{name} = _property(_itemgetter({index:d}), doc='Alias for field number {index:d}')
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'''
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def namedtuple(typename, field_names, verbose=False, rename=False):
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"""Returns a new subclass of tuple with named fields.
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>>> Point = namedtuple('Point', 'x y')
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>>> Point = namedtuple('Point', ['x', 'y'])
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>>> Point.__doc__ # docstring for the new class
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'Point(x, y)'
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>>> p = Point(11, y=22) # instantiate with positional args or keywords
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@ -287,66 +335,27 @@ def namedtuple(typename, field_names, verbose=False, rename=False):
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raise ValueError('Encountered duplicate field name: %r' % name)
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seen_names.add(name)
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# Create and fill-in the class template
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template = '''class {typename}(tuple):
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'{typename}({argtxt})'
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__slots__ = ()
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_fields = {field_names!r}
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def __new__(_cls, {argtxt}):
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'Create new instance of {typename}({argtxt})'
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return _tuple.__new__(_cls, ({argtxt}))
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@classmethod
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def _make(cls, iterable, new=tuple.__new__, len=len):
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'Make a new {typename} object from a sequence or iterable'
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result = new(cls, iterable)
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if len(result) != {numfields:d}:
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raise TypeError('Expected {numfields:d} arguments, got %d' % len(result))
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return result
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def __repr__(self):
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'Return a nicely formatted representation string'
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return self.__class__.__name__ + '({reprtxt})' % self
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def _asdict(self):
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'Return a new OrderedDict which maps field names to their values'
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return OrderedDict(zip(self._fields, self))
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def _replace(_self, **kwds):
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'Return a new {typename} object replacing specified fields with new values'
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result = _self._make(map(kwds.pop, {field_names!r}, _self))
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if kwds:
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raise ValueError('Got unexpected field names: %r' % kwds.keys())
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return result
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def __getnewargs__(self):
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'Return self as a plain tuple. Used by copy and pickle.'
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return tuple(self)
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'''
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template = template.format(
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# Fill-in the class template
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class_definition = _class_template.format(
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typename = typename,
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field_names = field_names,
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argtxt = repr(field_names).replace("'", "")[1:-1],
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numfields = len(field_names),
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reprtxt = ', '.join('{}=%r'.format(name) for name in field_names),
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num_fields = len(field_names),
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arg_list = repr(field_names).replace("'", "")[1:-1],
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repr_fmt = ', '.join(_repr_template.format(name=name) for name in field_names),
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field_defs = '\n'.join(_field_template.format(index=index, name=name)
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for index, name in enumerate(field_names))
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)
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for i, name in enumerate(field_names):
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template += " %s = _property(_itemgetter(%d), doc='Alias for field number %d')\n" % (name, i, i)
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if verbose:
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print(template)
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print(class_definition)
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# Execute the template string in a temporary namespace and
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# Execute the class definition string in a temporary namespace and
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# support tracing utilities by setting a value for frame.f_globals['__name__']
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namespace = dict(_itemgetter=_itemgetter, __name__='namedtuple_%s' % typename,
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OrderedDict=OrderedDict, _property=property, _tuple=tuple)
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try:
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exec(template, namespace)
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exec(class_definition, namespace)
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except SyntaxError as e:
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raise SyntaxError(e.msg + ':\n\n' + template)
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raise SyntaxError(e.msg + ':\n\n' + class_definition)
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result = namespace[typename]
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# For pickling to work, the __module__ variable needs to be set to the frame
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