From 81b9656989e2acce6209184826ca135a712e3f8b Mon Sep 17 00:00:00 2001 From: Raymond Hettinger Date: Mon, 2 May 2011 09:50:15 -0700 Subject: Backport code cleanup for namedtuples. --- Lib/collections.py | 135 ++++++++++++++++++++++++++++++++--------------------- 1 file changed, 81 insertions(+), 54 deletions(-) diff --git a/Lib/collections.py b/Lib/collections.py index ec7faeb..3693926 100644 --- a/Lib/collections.py +++ b/Lib/collections.py @@ -236,10 +236,62 @@ class OrderedDict(dict): ### 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 @@ -264,79 +316,54 @@ def namedtuple(typename, field_names, verbose=False, rename=False): # 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 -- cgit v0.12