Scott David Daniels wrote:
> Here is a Mix-in class I just built for testing.
> It is quite simple, but illustrates how Mixins
> can be used.
>
> class Pending(object):
> _pending = iter(())
> def __new__(class_, *args, **kwargs):
> try:
> return class_._pending.next()
> except StopIteration:
> return super(Pending, class_).__new__(class_,
> *args, **kwargs)
>
> Now for the use:
>
> class Float(Pending, float): pass
>
> Float._pending = iter(range(4,7))
>
> print [Float(x*(x+1)//2) for x in range(6)]
>
> Possibly by using itertools functions such as chain as in:
> Klass._pending = itertools.chain(generate_some(), Klass._pending)
> you can inject fixed values to simplify testing.
If you're willing to allow for issubclass() to fail you can do without a
mixin:
from itertools import chain, repeat
def preload(class_, iterable):
items = chain(
(lambda *args, **kw: item for item in iterable), repeat(class_))
return lambda *args, **kw: items.next()(*args, **kw)
float = preload(float, "ABC")
print [float(x) for x in range(6)]
issubclass(float, float) # TypeError
Argh :-)
Peter
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