Can you initialise multiple instances of a class in one single line?

Question

Imagine I would like to compact my code when initialising several instances of a class.

This code works:

from ipywidgets import Output,HBox
out1 = Output(layout={'border': '1px solid black'})
out2 = Output(layout={'border': '1px solid black'})
out3 = Output(layout={'border': '1px solid black'})

with out1: display('here is out1')
with out2: display('here is out2')
with out3: display('here is out3')

display(HBox([out1,out2,out3]))

Now what I want is not having to repeat three times the initialization of out1, out2, and out3.

Of course this does not work:

out1=out2=out3=Output(layout={'border': '1px solid black'})

because those three outs are the same object.

Imagine you have like 10 initialisations to do, what is a nice pythonic way to go about it without having to write 10 lines of code?

Other consultations that could not really help me: Automatically initialize multiple instance of class Can one initialize multiple variables of some type in one line? Python creating multiple instances for a single object/class

Opinion based, but you should be more interested in code clarity than the number of lines. Have you considered a loop or list comprehension, or a factory constructor function? https://en.wikipedia.org/wiki/Factory_method_pattern — Kenny Ostrom, Nov 10 '21 at 17:26
`out1, out2, out3 = [Output(layout={'border': '1px solid black'}) for i in range(3)]`? — not_speshal, Nov 10 '21 at 17:29

score 4 · Accepted Answer · answered Nov 10 '21 at 17:25

Create the Output objects in a list, and then you can iterate through the list:

outputs = [Output(layout={'border': '1px solid black'}) for _ in range(3)]

for i, out in enumerate(outputs, 1):
    with out:
        display(f"here is out{i}")

display(HBox(outputs))

score 2 · Answer 2 · answered Nov 10 '21 at 17:25

If you don't mind keeping those variables in a list, I would consider a loop that calls a function

from ipywidgets import Output,HBox

def get_obj():
    return Output(layout={'border': '1px solid black'})

def do_display(out, i):
    with out: display(f"here is out{i}")

outs = [get_obj() for _ in range(3)]
for i, out in enumerate(outs):
    do_display(out, i)

Can you initialise multiple instances of a class in one single line?

2 Answers2