Deleted namedtuple, fixed bug in piecewise
pbrod
9 years ago
parent
30dfdfb497
commit
c4e5bfd66a
@ -1,144 +0,0 @@
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from operator import itemgetter as _itemgetter
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from keyword import iskeyword as _iskeyword
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import sys as _sys
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def namedtuple(typename, field_names, verbose=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.__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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>>> p[0] + p[1] # indexable like a plain tuple
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33
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>>> x, y = p # unpack like a regular tuple
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>>> x, y
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(11, 22)
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>>> p.x + p.y # fields also accessable by name
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33
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>>> d = p._asdict() # convert to a dictionary
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>>> d['x']
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11
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>>> Point(**d) # convert from a dictionary
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Point(x=11, y=22)
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>>> p._replace(x=100) # _replace() is like str.replace() but targets named fields
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Point(x=100, y=22)
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"""
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# Parse and validate the field names. Validation serves two purposes,
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# generating informative error messages and preventing template injection
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# attacks.
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if isinstance(field_names, basestring):
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# names separated by whitespace and/or commas
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field_names = field_names.replace(',', ' ').split()
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field_names = tuple(field_names)
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for name in (typename,) + field_names:
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if not min(c.isalnum() or c == '_' for c in name):
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raise ValueError(
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'Type names and field names can only contain alphanumeric ' +
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'characters and underscores: %r' % name)
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if _iskeyword(name):
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raise ValueError(
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'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 ' +
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'with a number: %r' % name)
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seen_names = set()
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for name in field_names:
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if name.startswith('_'):
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raise ValueError(
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'Field names cannot start with an underscore: %r' % name)
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if name in seen_names:
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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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numfields = len(field_names)
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# tuple repr without parens or quotes
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argtxt = repr(field_names).replace("'", "")[1:-1]
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reprtxt = ', '.join('%s=%%r' % name for name in field_names)
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dicttxt = ', '.join('%r: t[%d]' % (name, pos)
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for pos, name in enumerate(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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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 '%(typename)s(%(reprtxt)s)' %% self \n
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def _asdict(t):
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'Return a new dict which maps field names to their values'
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return {%(dicttxt)s} \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\n''' % locals()
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for i, name in enumerate(field_names):
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template += ' %s = property(itemgetter(%d))\n' % (name, i)
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if verbose:
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print template
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# Execute the template string in a temporary namespace
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namespace = dict(itemgetter=_itemgetter)
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try:
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exec template in namespace
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except SyntaxError, e:
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raise SyntaxError(e.message + ':\n' + template)
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result = namespace[typename]
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# For pickling to work, the __module__ variable needs to be set to the
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# frame where the named tuple is created. Bypass this step in enviroments
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# where sys._getframe is not defined (Jython for example).
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if hasattr(_sys, '_getframe'):
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result.__module__ = _sys._getframe(1).f_globals['__name__']
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return result
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if __name__ == '__main__':
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# verify that instances can be pickled
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from cPickle import loads, dumps
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Point = namedtuple('Point', 'x, y', True)
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p = Point(x=10, y=20)
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assert p == loads(dumps(p))
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# test and demonstrate ability to override methods
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class Point(namedtuple('Point', 'x y')):
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@property
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def hypot(self):
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return (self.x ** 2 + self.y ** 2) ** 0.5
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def __str__(self):
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return 'Point: x=%6.3f y=%6.3f hypot=%6.3f' % (self.x, self.y,
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self.hypot)
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for p in Point(3, 4), Point(14, 5), Point(9. / 7, 6):
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print(p)
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class Point(namedtuple('Point', 'x y')):
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'''Point class with optimized _make() and _replace()
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without error-checking
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'''
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_make = classmethod(tuple.__new__)
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def _replace(self, _map=map, **kwds):
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return self._make(_map(kwds.get, ('x', 'y'), self))
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print(Point(11, 22)._replace(x=100))
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import doctest
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TestResults = namedtuple('TestResults', 'failed attempted')
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print(TestResults(*doctest.testmod()))
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