class declaration shortcut

[Steven Bethard]

Arnaud Delobelle wrote:
> On Mar 1, 4:01 pm, Steven Bethard <steven.beth... at gmail.com> wrote:
>> Arnaud Delobelle wrote:
> [...]
>> This does pretty much the same thing as the recipe I posted:
> 
> Not at all.  My new_struct create returns a new class which is similar
> to a C struct (notice the __slots__).  The recipe you refer to is
> nothing more a class which can be initialised with some attributes. It
> does not address the OP's question at all.
> 
>>      http://aspn.activestate.com/ASPN/Cookbook/Python/Recipe/502237

Huh?  It uses __slots__ in almost exactly the same way.  If you just 
s/Struct/Record in your ``new_struct`` function, you'll get essentially 
the same behavior, except that if you use the recipe, you'll get an 
__init__ that handles positional arguments, and displays better help::

     >>> def new_struct(name, *slots):
     ...     return type(name, (Struct,), {'__slots__': slots})
     ...
     >>> Person = new_struct('Person', 'name')
     >>> Person('Bob')
     Traceback (most recent call last):
       File "<interactive input>", line 1, in <module>
     TypeError: __init__() takes exactly 1 argument (2 given)
     >>> Person(name='Bob')
     Person(name='Bob')
     >>> help(Person.__init__)
     Help on method __init__ in module __main__:

     __init__(self, **vals) unbound __main__.Person method

     >>> def new_struct(name, *slots):
     ...     return type(name, (Record,), {'__slots__': slots})
     ...
     >>> Person = new_struct('Person', 'name')
     >>> Person('Bob')
     Person(name='Bob')
     >>> help(Person.__init__)
     Help on method __init__:

     __init__(self, name) unbound records.Person method


Maybe I'm not understanding you?

Steve