Chaining instance methods in python

Question

I would like create a class in python with method and sub-method.

Example what I want to do :

foo = Foo()
foo.playlist('my playlist').add('i_add_a_track_in_"my playlist".ogg')
foo.playlist('my playlist').delete('i_remove_this_track.ogg')

I have this code for now :

class Foo(object):
    def playlist(self, name):
        pass #my function...
    def add(self, track):
        pass #adding track
    def delete(self, track):
        pass #delete track

Please help me, I don't know how i can do it.

Thank you

Answer 1

IIUC, you want to chain method calls one after another? All you'd have to do is return self at the end of each function.

class Foo(object):
    ...   
    def playlist(self, name):
        ...
        return self

    ... # and so on

MVCE:

In [229]: class Foo:
     ...:     def __init__(self, data):
     ...:         self.data = data
     ...:
     ...:     def add(self, val):
     ...:         self.data += val
     ...:         return self
     ...:
     ...:     def sub(self, val):
     ...:         self.data -= val
     ...:         return self
     ...:     

In [231]: x = Foo(0)

In [232]: x = x.add(10).sub(5) # or just x.add(10).sub(5)

In [233]: x.data
Out[233]: 5