### namedtuple
################################################################################
+_class_template = '''\
+from builtins import property as _property, tuple as _tuple
+from operator import itemgetter as _itemgetter
+from collections import OrderedDict
+
+class {typename}(tuple):
+ '{typename}({arg_list})'
+
+ __slots__ = ()
+
+ _fields = {field_names!r}
+
+ def __new__(_cls, {arg_list}):
+ 'Create new instance of {typename}({arg_list})'
+ return _tuple.__new__(_cls, ({arg_list}))
+
+ @classmethod
+ def _make(cls, iterable, new=tuple.__new__, len=len):
+ 'Make a new {typename} object from a sequence or iterable'
+ result = new(cls, iterable)
+ if len(result) != {num_fields:d}:
+ raise TypeError('Expected {num_fields:d} arguments, got %d' % len(result))
+ return result
+
+ def __repr__(self):
+ 'Return a nicely formatted representation string'
+ return self.__class__.__name__ + '({repr_fmt})' % self
+
+ def _asdict(self):
+ 'Return a new OrderedDict which maps field names to their values'
+ return OrderedDict(zip(self._fields, self))
+
+ def _replace(_self, **kwds):
+ 'Return a new {typename} object replacing specified fields with new values'
+ result = _self._make(map(kwds.pop, {field_names!r}, _self))
+ if kwds:
+ raise ValueError('Got unexpected field names: %r' % list(kwds))
+ return result
+
+ def __getnewargs__(self):
+ 'Return self as a plain tuple. Used by copy and pickle.'
+ return tuple(self)
+
+{field_defs}
+'''
+
+_repr_template = '{name}=%r'
+
+_field_template = '''\
+ {name} = _property(_itemgetter({index:d}), doc='Alias for field number {index:d}')
+'''
+
def namedtuple(typename, field_names, verbose=False, rename=False):
"""Returns a new subclass of tuple with named fields.
- >>> Point = namedtuple('Point', 'x y')
+ >>> Point = namedtuple('Point', ['x', 'y'])
>>> Point.__doc__ # docstring for the new class
'Point(x, y)'
>>> p = Point(11, y=22) # instantiate with positional args or keywords
# generating informative error messages and preventing template injection attacks.
if isinstance(field_names, str):
field_names = field_names.replace(',', ' ').split() # names separated by whitespace and/or commas
- field_names = tuple(map(str, field_names))
+ field_names = list(map(str, field_names))
if rename:
- names = list(field_names)
seen = set()
- for i, name in enumerate(names):
- if (not all(c.isalnum() or c=='_' for c in name) or _iskeyword(name)
- or not name or name[0].isdigit() or name.startswith('_')
+ for index, name in enumerate(field_names):
+ if (not all(c.isalnum() or c=='_' for c in name)
+ or _iskeyword(name)
+ or not name
+ or name[0].isdigit()
+ or name.startswith('_')
or name in seen):
- names[i] = '_%d' % i
+ field_names[index] = '_%d' % index
seen.add(name)
- field_names = tuple(names)
- for name in (typename,) + field_names:
+ for name in [typename] + field_names:
if not all(c.isalnum() or c=='_' for c in name):
raise ValueError('Type names and field names can only contain alphanumeric characters and underscores: %r' % name)
if _iskeyword(name):
raise ValueError('Type names and field names cannot be a keyword: %r' % name)
if name[0].isdigit():
raise ValueError('Type names and field names cannot start with a number: %r' % name)
- seen_names = set()
+ seen = set()
for name in field_names:
if name.startswith('_') and not rename:
raise ValueError('Field names cannot start with an underscore: %r' % name)
- if name in seen_names:
+ if name in seen:
raise ValueError('Encountered duplicate field name: %r' % name)
- seen_names.add(name)
-
- # Create and fill-in the class template
- numfields = len(field_names)
- argtxt = repr(field_names).replace("'", "")[1:-1] # tuple repr without parens or quotes
- reprtxt = ', '.join('%s=%%r' % name for name in field_names)
- template = '''class %(typename)s(tuple):
- '%(typename)s(%(argtxt)s)' \n
- __slots__ = () \n
- _fields = %(field_names)r \n
- def __new__(_cls, %(argtxt)s):
- 'Create new instance of %(typename)s(%(argtxt)s)'
- return _tuple.__new__(_cls, (%(argtxt)s)) \n
- @classmethod
- def _make(cls, iterable, new=tuple.__new__, len=len):
- 'Make a new %(typename)s object from a sequence or iterable'
- result = new(cls, iterable)
- if len(result) != %(numfields)d:
- raise TypeError('Expected %(numfields)d arguments, got %%d' %% len(result))
- return result \n
- def __repr__(self):
- 'Return a nicely formatted representation string'
- return self.__class__.__name__ + '(%(reprtxt)s)' %% self \n
- def _asdict(self):
- 'Return a new OrderedDict which maps field names to their values'
- return OrderedDict(zip(self._fields, self)) \n
- def _replace(_self, **kwds):
- 'Return a new %(typename)s object replacing specified fields with new values'
- result = _self._make(map(kwds.pop, %(field_names)r, _self))
- if kwds:
- raise ValueError('Got unexpected field names: %%r' %% kwds.keys())
- return result \n
- def __getnewargs__(self):
- 'Return self as a plain tuple. Used by copy and pickle.'
- return tuple(self) \n\n''' % locals()
- for i, name in enumerate(field_names):
- template += " %s = _property(_itemgetter(%d), doc='Alias for field number %d')\n" % (name, i, i)
- if verbose:
- print(template)
+ seen.add(name)
+
+ # Fill-in the class template
+ class_definition = _class_template.format(
+ typename = typename,
+ field_names = tuple(field_names),
+ num_fields = len(field_names),
+ arg_list = repr(tuple(field_names)).replace("'", "")[1:-1],
+ repr_fmt = ', '.join(_repr_template.format(name=name) for name in field_names),
+ field_defs = '\n'.join(_field_template.format(index=index, name=name)
+ for index, name in enumerate(field_names))
+ )
# Execute the template string in a temporary namespace and
# support tracing utilities by setting a value for frame.f_globals['__name__']
- namespace = dict(_itemgetter=_itemgetter, __name__='namedtuple_%s' % typename,
- OrderedDict=OrderedDict, _property=property, _tuple=tuple)
+ namespace = dict(__name__='namedtuple_%s' % typename)
try:
- exec(template, namespace)
+ exec(class_definition, namespace)
except SyntaxError as e:
- raise SyntaxError(e.msg + ':\n\n' + template)
+ raise SyntaxError(e.msg + ':\n\n' + class_definition)
result = namespace[typename]
+ if verbose:
+ print(class_definition)
# For pickling to work, the __module__ variable needs to be set to the frame
# where the named tuple is created. Bypass this step in enviroments where
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