generic object - moving toward PEP

Dieter Maurer dieter at handshake.de
Sun Nov 21 19:30:33 CET 2004


Steven Bethard <steven.bethard at gmail.com> writes on Fri, 19 Nov 2004 21:38:14 GMT:
> ...
> Some arguments for a generic object:
> 
> (1) Allows a simple syntax for returning named results:
> 
>  >>> def f(x):
> .... 	return bunch(double=2*x, squared=x**2)
> ....
>  >>> y = f(10)
>  >>> y.double
> 20
>  >>> y.squared
> 100
> 
> (2) Allows simple representation of hierarchical data:
> 
>  >>> x = bunch(a=bunch(b=1, c=10), d=100)
>  >>> x.a.b
> 1
>  >>> x.d
> 100
> ...
> (3) Allows simple conversion from dict-style access to attribute access:
> 
>  >>> d = {'a':2, 'b':4, 'c':16, 'd':256}
>  >>> d['a'], d['d']
> (2, 256)
>  >>> b = bunch(**d)
>  >>> b.a, b.d
> (2, 256)
> 
> This could actually be supported recursively, if that seems useful:
> 
>  >>> d = {'a':2, 'b':4, 'c':{'d':16, 'e':256}}
>  >>> b = bunch.frommapping(d)
>  >>> b.c.d
> 16

How about:

        class bunch:
          def __init__(self, d__=None, **kw):
            d = self.__dict__
            if d__ is not None: d.update(d__)
            d.update(kw)


You can drop the "d__" magic, when you do not need direct
"dict --> bunch" conversion (of the form "bunch(dict)")
but use a special method ("frommapping") for this.

--
Dieter



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