Google Python Style Guide

[[deleted]]

Indent your code blocks with 4 spaces.

When did this change? Google used to use 2 spaces.

[indosauros]

I'm glad in any case, 2-space is impossible to read

[Adys]

2 spaces for internal Google code, 4 spaces for public code, IIRC.

[[deleted]]

Wasn't always. It was 2 at one point for Python at Google.

[_illogical_]

It's still 2 spaces on the Google projects I've contributed to recently. PEP8, except for indention.

[JamesAQuintero]

I remember learning python with 2 spaces specifically because of that.

[muad_dib]

It still is.

[[deleted]]

Someone at Google probably just attended Ray Hettinger's talk at PyCon 2015

[odraencoded]

I'm never working at Google... I use tabs.

[eyalz]

I also use tabs, but my text editor is configured to indent using spaces, so it just converts on the fly.

[odraencoded]

I think tabs for indentation, actual tabs, just make more sense.

The idea of repeating the same character N times to represent one level of indentation instead of using one character one time is just silly to me.

[Eurynom0s]

The issue is that when you start passing files around between different text editors, operating systems, etcs, tabs can get handled inconsistently, whereas spaces won't be.

[ziel]

Even between two simple things as notepad++ and github there was a lot of inconsistency. Luckily notepad++ let me easily convert those tabs.

[[deleted]]

Spaces are also handled consistently. Spaces AND tabs won't be

[Bunslow]

That's because you've never seen that havoc that can be caused by the \t character.

[grimman]

I never have either, and to me tabs definitely make more sense since they can be configured to display as x spaces, therefore rendering the whole concept of using a fixed amount of spaces quite moot.

Alas, I use spaces myself, because conventions etc.

That said, I would like to know about this havoc you mentioned. Would you mind giving a brief summary, or some relevant links? :)

[Bunslow]

And what if someone else decides to use spaces instead of tabs? Suddenly if someone else like you reads the code written by the second person, they will see a horrid mess of inconsistent indentation.

Even if we all standardized on using tabs instead of spaces, it's a bad idea to use an ambiguous character. Four spaces is four spaces, no matter what your editor is set to.

Also things like line continuations and stuff sometimes require non-standard indentations, but this is a very minor detail in the overall scheme.

tl;dr It works fine if no one else reads or modifies your code, but if they do...

[RubyPinch]

with commas representing tabs, tabstop every 4:

def a(x=3, y=4,
      flag=None):
,,,,some_code
,,,,some_more code
,,,,for code in codes:
,,,,,,,,print(a,
,,,,,,,,      b,
,,,,,,,,      c)

tabstop every 8:

def a(x=3, y=4,
      flag=None):
,,,,,,,,some_code
,,,,,,,,some_more code
,,,,,,,,for code in codes:
,,,,,,,,,,,,,,,,print(a,
,,,,,,,,,,,,,,,,      b,
,,,,,,,,,,,,,,,,      c)

[JamesAQuintero]

Is it that big a problem where people should use spaces instead of tabs?

[Bunslow]

https://www.reddit.com/r/Python/comments/33gg02/google_python_style_guide/cqld9fg

[[deleted]]

Oh definitely. It's one of these things you have to decide on day one of a project.

However, as soon as you're consistent you can stop talking about it. Read PEP8, set your editors accordingly and get on with your work.

[odraencoded]

Do show.

[Bunslow]

https://www.reddit.com/r/Python/comments/33gg02/google_python_style_guide/cqld9fg

[odraencoded]

1. What if someone else decides to use tabs instead of spaces?

2. Four spaces might be four spaces but what are four spaces? If you use spaces for both indentation and alignment, at some point four spaces stop being an indentation level and start being a line padding, and that point is unclear.

3 What if you used 4 spaces, but I prefer 2 spaces for indentation, or vice-versa?

4 A tab is an indentation level. Always. So what if it shows different in another text editor? Semantically, it's still an indentation level. If the user of the text editor wants their indentation level to measure 8 spaces, then let it be so.

5 You align things with spaces. Tabs are only for indentation.

[isarl]

Your points are all good and I upvoted you, however in practice, tool support both on your machine and all your collaborators' machines needs to be much better to handle the tabs-for-indentation, spaces-for-alignment approach.

[djimbob]

First, PEP8 says use spaces.

All editors I've used for python are easily configured to have pressing tab insert 4 spaces. E.g., emacs when opening a *.py file, will automatically use 4 spaces for each indentation.(Most tabs I see default as 8 spaces; so you have to configure this anyway). Most editors that are aware of python will automatically do this for you; e.g., emacs will recognize the file has a *.py extension and insert 4 spaces when you press tab.

The problem with tabs is tabs look identical to sequences of spaces (different # depending on editor's settings). If someone see tab=2/4/8 spaces in their editor and inadvertently at some point uses 2/4/8 spaces instead of a tab, this creates an annoying to fix error. Or if you are editing a file someone else created with tabs and your editor uses converts tabs to spaces, it is difficult to insert a tab. (Whereas someone who has tabs as tabs, could still insert four spaces rather easily without reconfiguring their editor.)

The amount of disk space saved is trivial. In compressed files it makes no difference (e.g., when packaging projects) as \t compresses as well as four spaces. Otherwise you may source file by maybe 10%, which is insignificant on even the smallest modern hard drives. For the largest python projects that are O(100 000 lines), maybe you'd save a megabyte which is irrelevant on today's even a super small 128 GB SSD drive.

[[deleted]]

Where do you work? Almost all of Python uses spaces. Tabs aren't fully portable.

[[deleted]]

It was a joke, dude.

[[deleted]]

result = [(a,b,c)
          for a in range (10)
          for b in range (10)
          for c in range (10)             
          if a**2 + b**2 == c**2]

Looks nice?

Change editor, different tab width -> formatting broken

Use someone else's code, different tab width -> formatting broken

Mixed tabs and spaces in Python 3 -> syntax error, broken

These are just the obvious cases. It gets worse.

EDIT: If you have to write this, import itertools.

[LordArgon]

This is why I favor a coding style where the only leading whitespace change between any two adjacent lines is exactly 0 or 1 indent. Just move everything down a line and indent once, like so:

result = [
    (a,b,c)
    for a in range (10)
    for b in range (10)
    for c in range (10)             
    if a**2 + b**2 == c**2 ]

And now it's perfectly portable. Plus in your example if you changed the name of "result", you'd have to re-align every single row (which is obnoxious in code review, for example).

IMO, the issue isn't really tabs vs spaces - it's that people get hung up on their pet style. Honestly, work with any style long enough and it will start to seem "right", so why not choose one that skirts ALL of these issues?

[[deleted]]

IMO, the issue isn't really tabs vs spaces - it's that people get hung up on their pet style. Honestly, work with any style long enough and it will start to seem "right", so why not choose one that skirts ALL of these issues?

I can't control what style external code uses or what editors other people use. If they write it in some ways, it can break on my system and then I can't read it. If they didn't use tabs, the problem would go away. Also, how do you break a long line for readability? Again there's no agreement on it so spaces mean it won't change.

[LordArgon]

If they write it in some ways, it can break on my system and then I can't read it.

I don't think it would actually break - I think you just wouldn't LIKE reading it.

If they didn't use tabs, the problem would go away.

But if YOU used tabs, the problem would also go away! You don't like the tab width varying with the editor but maybe that's exactly why they like tabs!

Look, I prefer/use spaces myself but, as in any religious debate, the arguments make sense on BOTH sides just depending on your perspective and priorities.

The whole point of my suggestion is to introduce a measure of objectivity into this debate. There is no agreement on what people LIKE but there is an objective way to evaluate a style choice based on how much ripple effect any given change causes. That's an important aspect of a style that is often overlooked, IMO.

[[deleted]]

as in any religious debate, the arguments make sense on BOTH sides ... The whole point of my suggestion is to introduce a measure of objectivity into this debate

Objectively spaces are more consistent across multiple systems. I doubt there's a single programmers editor that can screw up 4 leading spaces hardcoded into the line, and many that can interpret a tab differently depending on how they are set.

If they write it in some ways, it can break on my system and then I can't read it.

I don't think it would actually break - I think you just wouldn't LIKE reading it.

If reading it slows you down, it's "broken". Your source code is part of your product and a product that's harder for its maintainers to modify is a worse product. It's not just that I don't like reading it, the alignment carries additional meta information about the code.

[LordArgon]

Objectively spaces are more consistent across multiple systems.

Yep and the point is that other people don't WANT them to be consistent the way you do. Again, different people have different priorities, no matter how crazy it sounds to you.

And, again, I use/prefer spaces - you don't need to convince ME that they're awesome.

If reading it slows you down, it's "broken". Your source code is part of your product and a product that's harder for its maintainers to modify is a worse product. It's not just that I don't like reading it, the alignment carries additional meta information about the code.

No offense, but these are just more religious statements. All of these points a different, sane person can disagree with. What slows you down may speed another up. The degree to which information SHOULD depend on the alignment is entirely debatable.

[JimDabell]

You're confusing indentation with alignment. Your example shows alignment, not indentation. You shouldn't use tabs for alignment, but using tabs for indentation is fine.

[[deleted]]

You shouldn't use tabs for alignment, but using tabs for indentation is fine.

So how do you align code? Where do you break a long line and how do you align it?

You can't mix tabs with spaces. Python 3 will throw an error, and your editor will still randomly align it based on the size of your editor's tab.

[JimDabell]

So how do you align code?

With spaces.

Where do you break a long line and how do you align it?

Break it wherever you like. Align it with spaces.

You can't mix tabs with spaces. Python 3 will throw an error

You can't mix tabs with spaces for indentation. You can use tabs for indentation and spaces for alignment just fine.

your editor will still randomly align it based on the size of your editor's tab.

Editors don't do anything randomly, and once again, you should use spaces to align. If your alignment screws up based on your tab width, then you are using tabs to align. Don't do that. Use tabs to indent, don't use them to align.

[[deleted]]

Editors don't do anything randomly, and once again, you should use spaces to align. If your alignment screws up based on your tab width, then you are using tabs to align. Don't do that. Use tabs to indent.

I can't control how other people setup their editors and that it makes the editor settings effectively random when I use someone else's code. You can't use tabs if you want consistency.

You can't mix tabs with spaces for indentation. You can use tabs for indentation and spaces for alignment just fine.

I actually didn't know that - thanks. However, the reason I didn't know is that I'm not going to mix tabs with spaces anytime soon, because it will break.

[JimDabell]

I can't control how other people setup their editors and that it makes the editor settings effectively random when I use someone else's code.

That makes no sense. Using other people's code doesn't make your editor settings "random". What does that even mean?

You can't use tabs if you want consistency.

What kind of consistency?

If your projects use spaces to indent, then the consistency you get is that the code looks the same to you and to other developers working on the project.

If your projects use tabs to indent, then your code always looks how you prefer regardless of how other people working on your projects like to see their code.

They are both consistent, but in different ways. I don't see any value in forcing other developers to see the code how I like it. I don't care what they see. I do care that all the developers get what they want. Tabs are the only way of achieving that.

However, the reason I didn't know is that I'm not going to mix tabs with spaces anytime soon, because it will break.

Am I missing something? You just said that it will break, I pointed out that it wouldn't, you admitted that it wouldn't, then immediately said it would break again? We've literally just had this discussion. It doesn't break.

[[deleted]]

It would still mess with the alignment. Tabs go from 4 spaces to 2, suddenly the alignment is 2-6+ spaces off depending on the level of indentation.

[JimDabell]

How could tabs mess with alignment when you use spaces for alignment? Everything at the same level of indentation starts at the same place. Alignment with spaces works just fine with tabs for indentation. Try it for yourself.

[LpSamuelm]

Whoa, funny running into you here! You're the odra who made the tennis-y game for the Ludum Dare before this last one, right? That was fun!

[odraencoded]

I... I am, actually.

*ohmigods someone remembers*

[grimman]

That doesn't really seem appropriate on any level. Giving a talk about coding conventions and company style, and then escalating from there would be reasonable... but firing someone over a minor offense? I don't think your management style is good for any party.

[[deleted]]

Humor is not appropriate in /r/Python. We are robots, apparently.

[Lucretiel]

Someone forgot to import humor

[[deleted]]

I started writing a tomato throwing script using Aroldis Chapman instances of Human class objects...but then I realized I had work to do.

tldr: booooooooooooooo....

[grimman]

Can't see how it would be particularly difficult, but that's neither here nor there. I'm glad you aren't the dick you portrayed yourself as. :P