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[Python-ideas] Decorators for variables

Eric Fahlgren ericfahlgren at gmail.com
Sun Apr 3 10:14:32 EDT 2016 
On Saturday, April 02, 2016 23:33, Chris Angelico wrote:
> On Sun, Apr 3, 2016 at 4:05 PM, Matthias welp <boekewurm at gmail.com> wrote:
> > currently changes behaviour depending on what kind of scope it is 
> > located in (class description, any other scope), while decorators (for 
> > functions at
> > least) work in every scope I can think of. I think that is strange, 
> > and that it should just be the same everywhere.
>
> Can you explain - or, preferably, demonstrate - the difference you're talking about here?

I can sort of see it, like this?

class C():
    def __init__(self):
        self.x = 99
    @property
    def f(self):
        return self.x

x = 101
@property
def f(namespace):
    return namespace.x

c = C()
print(c.x)
99
print(c.f)
99
print(C.f.fget(c))
99

print(x)
101

Here's the inconsistency, should implicitly bind to a "global namespace object".
print(f)
<property object at 0x00000000023FB6D8>

In other words, something like this:

class GNS:
    def __getattr__(self, name):
        prop = globals().get(name)
        if isinstance(prop, property):
            return prop.fget(self)
        return prop
global_namespace = GNS()

print(x is global_namespace.x, "should be 'True'")
True should be 'True'

print(global_namespace.f)
101
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