diff options
Diffstat (limited to 'Lib/collections.py')
| -rw-r--r-- | Lib/collections.py | 15 |
1 files changed, 10 insertions, 5 deletions
diff --git a/Lib/collections.py b/Lib/collections.py index 816f864c98..7b10712317 100644 --- a/Lib/collections.py +++ b/Lib/collections.py @@ -18,19 +18,21 @@ def NamedTuple(typename, s, verbose=False): (11, 22) >>> p.x + p.y # fields also accessable by name 33 - >>> p # readable __repr__ with name=value style + >>> 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 a named field Point(x=100, y=22) - >>> d = dict(zip(p.__fields__, p)) # use __fields__ to make a dictionary - >>> d['x'] - 11 """ field_names = tuple(s.replace(',', ' ').split()) # names separated by spaces and/or commas if not ''.join((typename,) + field_names).replace('_', '').isalnum(): raise ValueError('Type names and field names can only contain alphanumeric characters and underscores') + if any(name.startswith('__') and name.endswith('__') for name in field_names): + raise ValueError('Field names cannot start and end with double underscores') 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): @@ -41,7 +43,10 @@ def NamedTuple(typename, s, verbose=False): return tuple.__new__(cls, (%(argtxt)s)) def __repr__(self): return '%(typename)s(%(reprtxt)s)' %% self - def __replace__(self, field, value): + def __asdict__(self, dict=dict, zip=zip): + 'Return a new dict mapping field names to their values' + return dict(zip(%(field_names)r, self)) + def __replace__(self, field, value, dict=dict, zip=zip): 'Return a new %(typename)s object replacing one field with a new value' return %(typename)s(**dict(zip(%(field_names)r, self) + [(field, value)])) \n''' % locals() for i, name in enumerate(field_names): |