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[3.9] Simplify creation of the __new__ method in namedtuple() (GH-20361) #20409

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Merged
rhettinger merged 1 commit into from
May 26, 2020
Merged

[3.9] Simplify creation of the __new__ method in namedtuple() (GH-20361) #20409

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6 changes: 2 additions & 4 deletions Lib/collections/__init__.py
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Original file line number Diff line number Diff line change
Expand Up @@ -406,11 +406,9 @@ def namedtuple(typename, field_names, *, rename=False, defaults=None, module=Non

# Create all the named tuple methods to be added to the class namespace

s = f'def __new__(_cls, {arg_list}): return _tuple_new(_cls, ({arg_list}))'
s = f'lambda _cls, {arg_list}: _tuple_new(_cls, ({arg_list}))'
namespace = {'_tuple_new': tuple_new, '__name__': f'namedtuple_{typename}'}
# Note: exec() has the side-effect of interning the field names
exec(s, namespace)
__new__ = namespace['__new__']
__new__ = eval(s, namespace)
__new__.__doc__ = f'Create new instance of {typename}({arg_list})'
if defaults is not None:
__new__.__defaults__ = defaults
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