I have the following code:
class Stat(list):
def __init__(self, lst = []):
self.s = list(lst)
def __repr__(self):
return "Stat({})".format(self.s)
def add(self, item):
self.s.append(item)
def len(self):
return len(self.s)
...(more methods, but not necessary)
All of the methods work properly but len(). No matter the length of the Stat object, the returned length is always 0; I don't understand why.
it will return 0 always when you are using it like this:
x = Stat([1,3,4,5])
print len(x)
if you want to override len function use this code:
def __len__(self):
return len(self.s)
s = Stat([1, 2])
s.add(1)
s.add(2)
print s.len()
I have run your code, the result is correct in my environment.
len(object)Override the magic method __len__(self) to control the output of a call to len(my_stat_object):
class Stat(list):
def __init__(self, lst = []):
self.s = list(lst)
def __repr__(self):
return "Stat({})".format(self.s)
def add(self, item):
self.s.append(item)
def __len__(self):
return len(self.s)
If what you're trying to run is len(stat) and not stat.len(), your function len should be named __len__ instead. Here's the docs: object.len
stat = Stat([1, 2])
len(s) # 0 if len, 2 if __len__
As a side note, you might want to replace lst=[] in your init definition, as it can cause some weird looking behaviours. Read about it here: mutable default argument
lenmethod?list.len(Stat()), the special method name is__len__. The right way to call thelenmethod (as it’s just a method namedlen) on your current class is justStat().len(). But you wouldn’t need to inherit fromlistto do either of these. Pick one of wrappinglist(havingself.s) or inheriting from it.