Python alignment of assignments (style)

Question

I really like following style standards, as those specified in PEP 8. I have a linter that checks it automatically, and definitely my code is much better because of that.

There is just one point in PEP 8, the E251 & E221 don’t feel very good. Coming from a JavaScript background, I used to align the variable assignments as following:

var var1        = 1234;
    var2        = 54;
    longer_name = 'hi';

var lol = {
    'that'        : 65,
    'those'       : 87,
    'other_thing' : true
};

And in my humble opinion, this improves readability dramatically. Problem is, this is dis-recommended by PEP 8. With dictionaries, is not that bad because spaces are allowed after the colon:

dictionary = {
   'something':        98,
   'some_other_thing': False
}

I can "live" with variable assignments without alignment, but what I don’t like at all is not to be able to pass named arguments in a function call, like this:

some_func(length=      40,
          weight=      900,
          lol=         'troll',
          useless_var= True,
          intelligence=None)

So, what I end up doing is using a dictionary, as following:

specs = {
    'length':       40,
    'weight':       900,
    'lol':          'troll',
    'useless_var':  True,
    'intelligence': None
}

some_func(**specs)

or just simply

some_func(**{'length':       40,
             'weight':       900,
             'lol':          'troll',
             'useless_var':  True,
             'intelligence': None})

But I have the feeling this work around is just worse than ignoring the PEP 8 E251 / E221.

What is the best practice?

EDIT many years later

Don’t align. Sooner or later a new variable that is longer will come and your will have to hit spacebar here and there for a while until everything looks good again. Not worth it.

EDIT even more years later
Just use a code formatter like black and use it as pre-commit and/or your CI. Then forget about this.

Asked By: bgusach

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Source

Answer 1

So, what I end up doing is using a dictionary, as following:

specs = {
    length:      40,
    weight:      900,
    lol:         'troll',
    useless_var: True,
    intelligence:None
}

IMHO – this is less readable (were it valid syntax without quoting the keys), and if I happen to want to add some_longer_named_varible, I’m really not sure if I’d want to muck about re-spacing everything else.

I think you should just bite the bullet I’m afraid.

Answered By: Jon Clements

Answer 2

Best practice is subjective, but the most common practice is to stick to PEP8.

I definitely don’t suggest creating dictionaries every time you want to call a function with named arguments. That’s quite wasteful. I don’t see why your original some_func call wouldn’t work. I definitely break my function calls into lines if they get too long and unwieldy. But I do not align them. I imagine that the reason for the recommendation is because it can get to be a huge pain to maintain all of the spacing correctly over time, and the consensus was maintainability over the gain in prettyness.

If you’re working on your own code, align away, who cares? PEP8 is a guideline, not a law.

Answered By: acjay

Answer 3

I’d recommend sticking to PEP8. What happens if you need to change the name of one of your variables? An automated refactoring tool will change this:

var1        = 1234
var2        = 54
longer_name = 'hi'

to this:

var1        = 1234
var2        = 54
even_longer_name = 'hi'  # not aligned any more!

You’ll end up making more work for yourself to keep things aligned.

Answered By: Benjamin Hodgson

Python alignment of assignments (style)

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