How to implement chain operations in Python?

Question

class Array:
    def __init__(self):
        self.list = []

    def add(self, num):
        self.list.append(num)

a = Array()
a.add(1).add(2)

I would like to add number 1, 2 to self.list like this. How can I implement?

probably relevant for OP: stackoverflow.com/questions/36688966/… — timgeb
– timgeb, Commented Feb 23, 2017 at 19:15
Possible duplicate of Python way for object method chaining for class instance variables — TemporalWolf
– TemporalWolf, Commented Feb 23, 2017 at 19:30

metmirr · Accepted Answer · 2017-02-23 19:16:12Z

1

After your insertion returns the instance itself for second operation, then you will have instance itself so you can perform add operation:

def add(self, num):
    self.list.append(num)
    return self

answered Feb 23, 2017 at 19:16

metmirr

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Comments

rafaelc · Accepted Answer · 2017-02-23 19:14:29Z

1

Return the object itself

def add(self, num):
    self.list.append(num)
    return self

answered Feb 23, 2017 at 19:14

rafaelc

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MrName · Accepted Answer · 2017-02-23 19:21:53Z

0

As an alternative approach, why not just let your add method take a list of values as input? Seems like it would be easier to use like that

def add(self, vals):
    self.list += vals

So now you can

a.add([1,2])

Instead of

a.add(1).add(2)

answered Feb 23, 2017 at 19:21

MrName

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