On 10/19/05, Fredrik Lundh [EMAIL PROTECTED] wrote:
letting class inject a slightly magic self variable into the class
namespace ?
class C:
foo = property(self.getFoo, self.setFoo, None, 'the foo property')
def getFoo(self):
return self._foo
def setFoo(self, foo):
self._foo = foo
(figuring out exactly what self should be is left as an exercise etc)
It's magical enough to deserve to be called __self__. But even so:
I've seen proposals like this a few times in other contexts. I may
even have endorsed the idea at one time. The goal is always the same:
forcing delayed evaluation of a getattr operation without using either
a string literal or a lambda. But I find it quite a bit too magical,
for all values of xyzzy, that xyzzy.foo would return a function of one
argument that, when called with an argument x, returns x.foo. Even if
it's easy enough to write the solution (*), that sentence describing
it gives me goosebumps. And the logical consequence, xyzzy.foo(x),
which is an obfuscated way to write x.foo, makes me nervous.
(*) Here's the solution:
class XYZZY(object):
def __getattr__(self, name):
return lambda arg: getattr(arg, name)
xyzzy = XYZZY()
--
--Guido van Rossum (home page: http://www.python.org/~guido/)
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