Backport code cleanup for namedtuples.
This commit is contained in:
Raymond Hettinger
parent
cafa2efedb
commit
81b9656989
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@ -236,10 +236,62 @@ class OrderedDict(dict):
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### namedtuple
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################################################################################
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_class_template = '''\
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from builtins import property as _property, tuple as _tuple
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from operator import itemgetter as _itemgetter
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from collections import OrderedDict
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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' % list(kwds))
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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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@ -264,79 +316,54 @@ def namedtuple(typename, field_names, verbose=False, rename=False):
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# generating informative error messages and preventing template injection attacks.
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if isinstance(field_names, str):
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field_names = field_names.replace(',', ' ').split() # names separated by whitespace and/or commas
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field_names = tuple(map(str, field_names))
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field_names = list(map(str, field_names))
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if rename:
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names = list(field_names)
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seen = set()
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for i, name in enumerate(names):
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if (not all(c.isalnum() or c=='_' for c in name) or _iskeyword(name)
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or not name or name[0].isdigit() or name.startswith('_')
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for index, name in enumerate(field_names):
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if (not all(c.isalnum() or c=='_' for c in name)
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or _iskeyword(name)
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or not name
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or name[0].isdigit()
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or name.startswith('_')
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or name in seen):
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names[i] = '_%d' % i
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field_names[index] = '_%d' % index
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seen.add(name)
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field_names = tuple(names)
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for name in (typename,) + field_names:
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for name in [typename] + field_names:
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if not all(c.isalnum() or c=='_' for c in name):
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raise ValueError('Type names and field names can only contain alphanumeric characters and underscores: %r' % name)
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if _iskeyword(name):
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raise ValueError('Type names and field names cannot be a keyword: %r' % name)
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if name[0].isdigit():
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raise ValueError('Type names and field names cannot start with a number: %r' % name)
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seen_names = set()
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seen = set()
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for name in field_names:
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if name.startswith('_') and not rename:
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raise ValueError('Field names cannot start with an underscore: %r' % name)
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if name in seen_names:
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if name in seen:
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raise ValueError('Encountered duplicate field name: %r' % name)
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seen_names.add(name)
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seen.add(name)
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# Create and fill-in the class template
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numfields = len(field_names)
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argtxt = repr(field_names).replace("'", "")[1:-1] # tuple repr without parens or quotes
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reprtxt = ', '.join('%s=%%r' % name for name in field_names)
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template = '''class %(typename)s(tuple):
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'%(typename)s(%(argtxt)s)' \n
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__slots__ = () \n
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_fields = %(field_names)r \n
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def __new__(_cls, %(argtxt)s):
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'Create new instance of %(typename)s(%(argtxt)s)'
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return _tuple.__new__(_cls, (%(argtxt)s)) \n
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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)s 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 \n
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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)s)' %% self \n
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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)) \n
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def _replace(_self, **kwds):
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'Return a new %(typename)s 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 \n
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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) \n\n''' % locals()
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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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# 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 = tuple(field_names),
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num_fields = len(field_names),
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arg_list = repr(tuple(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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# Execute the template 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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namespace = dict(__name__='namedtuple_%s' % typename)
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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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if verbose:
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print(class_definition)
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# For pickling to work, the __module__ variable needs to be set to the frame
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# where the named tuple is created. Bypass this step in enviroments where
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