Overload __len__ method for len function
Overload __len__
__len__(self) returns the number of items contained in the collection.
If __len__ returns zero, the object is treated as false in a Boolean context.
class MyList:# from www . jav a 2 s .com
def __init__(self, start):
self.wrapped = [] # Make sure it's a list here.
for x in start: self.wrapped.append(x)
def __add__(self, other):
return MyList(self.wrapped + other)
def __mul__(self, time):
return MyList(self.wrapped * time)
def __getitem__(self, offset):
return self.wrapped[offset]
def __len__(self):
return len(self.wrapped)
def __getslice__(self, low, high):
return MyList(self.wrapped[low:high])
def append(self, node):
self.wrapped.append(node)
def __getattr__(self, name): # Other members: sort/reverse/etc
return getattr(self.wrapped, name)
def __repr__(self):
return self.wrapped
x = MyList('spam')
print x
print x[0]
print x[1:]
print x + ['eggs']
print x * 3
x.append('a')
x.sort( )
for c in x: print c,
The code above generates the following result.
