I'd like to do something like this:
class Foo:
def test(self, arg):
self.test.x = 'prop x with ' + arg
print "test!"
f = Foo()
f.test('bar')
print f.test.x
And get as an output something like this:
test!
prop x with bar
But instead I get an AttributeError: 'instancemethod' object has no attribute 'x'
By the way I can do such thing with function:
def test(arg):
test.x = 'prop x ' + arg
print "test!"
test('bar')
print test.x
which works just fine.
You can't do this; and even if you could, methods are properties of the class, not the instance, so the same value would be set for all all instances of Foo.
Instead you should simply assign directly to the instance. You can add whatever attributes you like.
class Foo:
def test(self, arg):
self._x = 'prop x with ' + arg
Even if you succeeded in setting the attribute, it wouldn't be preserved. In CPython, bound methods are created on the fly when you access them:
>>> class Foo:
... def test(self, arg): pass
...
>>> f = Foo()
>>> f.test is f.test
False
You can add members to a class instance, but not to a method.
class Foo:
def test(self, arg):
self.x = 'prop x with ' + arg
print "test!"
f = Foo()
f.test('bar')
print f.x
We can arrive/achieve what you are looking for by litle tweaking
from collections import namedtuple
T = namedtuple('T', ['x'])
class Foo:
def test(self, arg):
self.test = T('prop x with ' + arg)
print "test!"
f = Foo()
f.test('bar')
print f.test.x
Output will be:
test!
prop x with bar
Reason I called it a tweak is, from this point, f.test is no more a callable.
f.test is no longer callable
