Python: how to append to a list in the same line the list is declared?

Question

Is there any way to replace the following:

names = ['john', 'mike', 'james']
names.append('dan')
print(names)

with a one-liner similiar to this one (which will print None)?:

names = ['john', 'mike', 'james'].append('dan')
print(names)

Refer [this](https://stackoverflow.com/questions/1682567/why-does-list-append-evaluate-to-false-in-a-boolean-context) for why it is bad idea to append and assign it in same line. — Sociopath, Jan 03 '19 at 09:42
if you know beforehand that `'dan'` will be added to the list, why not initialize it with `'dan'` already in it? I fail to think of a real-life practical scenario for your question.. — Ma0, Jan 03 '19 at 09:43

score 5 · Answer 1 · answered Jan 03 '19 at 09:39

5

How about a adding them?

print(['john', 'mike', 'james'] + ['Dan'])
['john', 'mike', 'james', 'Dan']

Note that you have to add the second element as a list as you can only add elements of the same type, as it occurs with strings

answered Jan 03 '19 at 09:39

yatu

You can append any type of elements in a Python list: print(['john', 'mike', 'james'] + [1, [1,2]]) is still valid – Daedalus Jan 03 '19 at 09:47
You are adding two lists in your example. – yatu Jan 03 '19 at 09:48
I see know! You were referring to the list and not to the elements of the list. – Daedalus Jan 03 '19 at 09:53
Yes @HectorIX that's right – yatu Jan 03 '19 at 09:59

score 0 · Accepted Answer · answered Jan 03 '19 at 09:41

list.append is an in-place method, so it changes the list in-place and always returns None.

I don't think you can append elements while declaring the list. You can however, extend the new list by adding another list to the new list:

names = ['john', 'mike', 'james'] + ['dan']
print(names)

score 0 · Answer 3 · answered Jan 03 '19 at 09:45

names = ['john', 'mike', 'james']; names.append('dan')
#This is 1 line, note the semi-colon

This is slightly cheating, but then again, I fail to see the purpose of putting it on 1 line. Otherwise, just do as what the others have suggested:

names = ['john', 'mike', 'james'] + ['dan']

3 Answers3