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added attribute-like access to tuple and dict

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branch : aspn
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Andreas
2009-10-12 20:13:41 +00:00
parent ca23b54ac7
commit 39a64efbdd
2 changed files with 211 additions and 0 deletions
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33
src/attrdict.py Normal file
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# http://code.activestate.com/recipes/473786/
class AttrDict(dict):
"""A dictionary with attribute-style access. It maps attribute access to
the real dictionary. """
def __init__(self, init={}):
dict.__init__(self, init)
def __getstate__(self):
return self.__dict__.items()
def __setstate__(self, items):
for key, val in items:
self.__dict__[key] = val
def __repr__(self):
return "%s(%s)" % (self.__class__.__name__, dict.__repr__(self))
def __setitem__(self, key, value):
return super(AttrDict, self).__setitem__(key, value)
def __getitem__(self, name):
return super(AttrDict, self).__getitem__(name)
def __delitem__(self, name):
return super(AttrDict, self).__delitem__(name)
__getattr__ = __getitem__
__setattr__ = __setitem__
def copy(self):
ch = AttrDict(self)
return ch

178
src/namedtuple.py Normal file
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# http://code.activestate.com/recipes/500261/
from operator import itemgetter as _itemgetter
from keyword import iskeyword as _iskeyword
import sys as _sys
def namedtuple(typename, field_names, verbose=False, rename=False):
"""Returns a new subclass of tuple with named fields.
>>> 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
>>> p[0] + p[1] # indexable like a plain tuple
33
>>> x, y = p # unpack like a regular tuple
>>> x, y
(11, 22)
>>> p.x + p.y # fields also accessable by name
33
>>> d = p._asdict() # convert to a dictionary
>>> d['x']
11
>>> Point(**d) # convert from a dictionary
Point(x=11, y=22)
>>> p._replace(x=100) # _replace() is like str.replace() but targets named fields
Point(x=100, y=22)
"""
# Parse and validate the field names. Validation serves two purposes,
# generating informative error messages and preventing template injection attacks.
if isinstance(field_names, basestring):
field_names = field_names.replace(',', ' ').split() # names separated by whitespace and/or commas
field_names = tuple(map(str, field_names))
if rename:
names = list(field_names)
seen = set()
for i, name in enumerate(names):
if (not min(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
seen.add(name)
field_names = tuple(names)
for name in (typename,) + field_names:
if not min(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()
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:
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):
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 '%(typename)s(%(reprtxt)s)' %% self \n
def _asdict(self):
'Return a new dict which maps field names to their values'
return dict(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 tuple(self) \n\n''' % locals()
for i, name in enumerate(field_names):
template += ' %s = _property(_itemgetter(%d))\n' % (name, i)
if verbose:
print template
# Execute the template string in a temporary namespace
namespace = dict(_itemgetter=_itemgetter, __name__='namedtuple_%s' % typename,
_property=property, _tuple=tuple)
try:
exec template in namespace
except SyntaxError, e:
raise SyntaxError(e.message + ':\n' + template)
result = namespace[typename]
# 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
# sys._getframe is not defined (Jython for example) or sys._getframe is not
# defined for arguments greater than 0 (IronPython).
try:
result.__module__ = _sys._getframe(1).f_globals.get('__name__', '__main__')
except (AttributeError, ValueError):
pass
return result
def NamedTuple(typename, field_names):
if isinstance(field_names,str):
field_names = field_names.split()
nargs = len(field_names)
def __new__(cls, *args, **kwds):
if (len(args) == 1) and (getattr(args[0], '__iter__', False)):
args = tuple(name for name in args[0])
if kwds:
try:
args += tuple(kwds[name] for name in field_names[len(args):])
except KeyError, name:
raise TypeError('%s missing required argument: %s' % (typename, name))
if len(args) != nargs:
raise TypeError('%s takes exactly %d arguments (%d given)' % (typename, nargs, len(args)))
return tuple.__new__(cls, args)
repr_template = '%s(%s)' % (typename, ', '.join('%s=%%r' % name for name in field_names))
m = dict(vars(tuple)) # pre-lookup superclass methods (for faster lookup)
m.update(__doc__= '%s(%s)' % (typename, ', '.join(field_names)),
__slots__ = (), # no per-instance dict (so instances are same size as tuples)
__new__ = __new__,
__repr__ = lambda self, _format=repr_template.__mod__: _format(self),
__module__ = sys._getframe(1).f_globals['__name__'],
__field_names__ = tuple(field_names),
__from_iterable__=classmethod(__from_iterable__),
)
m.update((name, property(itemgetter(index))) for index, name in enumerate(field_names))
return type(typename, (tuple,), m)
if __name__ == '__main__':
# verify that instances can be pickled
from cPickle import loads, dumps
Point = namedtuple('Point', 'x, y', True)
p = Point(x=10, y=20)
assert p == loads(dumps(p, -1))
# test and demonstrate ability to override methods
class Point(namedtuple('Point', 'x y')):
@property
def hypot(self):
return (self.x ** 2 + self.y ** 2) ** 0.5
def __str__(self):
return 'Point: x=%6.3f y=%6.3f hypot=%6.3f' % (self.x, self.y, self.hypot)
for p in Point(3,4), Point(14,5), Point(9./7,6):
print p
class Point(namedtuple('Point', 'x y')):
'Point class with optimized _make() and _replace() without error-checking'
_make = classmethod(tuple.__new__)
def _replace(self, _map=map, **kwds):
return self._make(_map(kwds.get, ('x', 'y'), self))
print Point(11, 22)._replace(x=100)
import doctest
TestResults = namedtuple('TestResults', 'failed attempted')
print TestResults(*doctest.testmod())