I have a class that looks like this:
class A(object):
def __init__(self):
self.var_a = []
self.var_b = []
Is there a way I can define __str__
on A
such that I can pass an index in this fashion:
instance_a = A()
# do stuff with instance_a causing var_a and var_b to populate
print( instance_a[idx] )
and get __str__
to utilise the index and return something like:
return "var_a is " + str(var_a[idx]) + ", var_b is" + str(var_b[idx])
To format strings with parameters, use __format__
:
class A(object):
def __init__(self):
self.var_a = []
self.var_b = []
def __format__(self, idx):
idx = int(idx)
return "var_a is {}, var_b is {}".format(self.var_a[idx], self.var_b[idx])
Example:
>>> a = A()
>>> a.var_a=[4,5,6]
>>> a.var_b=[1,2,3]
>>> '{:1}'.format(a)
'var_a is 5, var_b is 2'
What you're looking for is __getitem__
, not __str__
.
class A(object):
def __init__(self):
self.var_a = []
self.var_b = []
def __getitem__(self, idx):
return "var_a is " + str(self.var_a[idx]) + ", var_b is" + str(self.var_b[idx])
>>> a = A()
>>> a.var_a = [1,2,3]
>>> a.var_b = [4,5,6]
>>> print(a[2])
var_a is 3, var_b is6
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