python's OOP question

[neoedmund]

There's a program, it's result is "unexpected aaa", i want it to be
"expected aaa". how to make it work?

 
class C1(object):
def v(self, o):
return "expected "+o
 
class C2(object):
def v(self, o):
return "unexpected "+o
def m(self):
print self.v("aaa")
 
class C3(object):
def nothing(self):
pass
 
def test1():
o = C3()
setattr(o,"m",C2().m)
setattr(o,"v",C1().v)
o.m()
 
test1()
 
 

[Ben Finney]

"neoedmund" <ne*******@gmai l.comwrites:

Bruno Desthuilliers wrote:

neoedmund wrote:

in real life, a class is not defined so well that any method is
needed by sub-class.

Then perhaps is it time to refactor. A class should be a highly
cohesive unit. If you find yourself needing only a specific subset
of a class, it may be time to extract this subset in it's own
class.

I donnot agree with your "it's time to refactory" very much, man has
probly never has time to do such things.

I respectfully suggest that the *reason* you find yourself with little
time to refactor is probably related to the fact that you *need* to
refactor. If your code is crufty and poorly-designed, it is costing
you every time you need to maintain it.

Would it help if we called it "preventati ve maintenance"?

--
\ "I bought a dog the other day. I named him Stay. It's fun to |
`\ call him. 'Come here, Stay! Come here, Stay!' He went insane. |
_o__) Now he just ignores me and keeps typing." -- Steven Wright |
Ben Finney

[Neil Cerutti]

On 2006-10-18, neoedmund <ne*******@gmai l.comwrote:

ivestgating the web, i found something similiar with my approch:
http://en.wikipedia.org/wiki/Duck_typing
"Duck-typing avoids tests using type() or isinstance(). Instead, it
typically employs hasattr() tests"

It's pity it didn't get called quack typing. One ckecks if
some unknown noun can quack, not if a duck can do something
unknown.

--
Neil Cerutti

[Peter Otten]

Neil Cerutti wrote:

On 2006-10-18, neoedmund <ne*******@gmai l.comwrote:

>ivestgating the web, i found something similiar with my approch:
http://en.wikipedia.org/wiki/Duck_typing
"Duck-typing avoids tests using type() or isinstance(). Instead, it
typically employs hasattr() tests"

It's pity it didn't get called quack typing.

That's because the quacks recommend static typing.

Peter

[Peter Otten]

Neil Cerutti wrote:

On 2006-10-18, neoedmund <ne*******@gmai l.comwrote:

>ivestgating the web, i found something similiar with my approch:
http://en.wikipedia.org/wiki/Duck_typing
"Duck-typing avoids tests using type() or isinstance(). Instead, it
typically employs hasattr() tests"

It's pity it didn't get called quack typing.

That's because the quacks prescribe static typing.

Peter