Python: using 4 spaces for indentation. Why? [clos

Question

While coding python I'm using only 2 spaces to indent, sure PEP-8 really recommend to have 4 spaces, but historically for me it's unusual.

So, can anyone convince me to use 4 spaces instead of 2? What pros and cons?

P.S. And finally, what's easy way to convert all existing codebase from 2 spaces to 4 spaces?

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P.P.S. PEP-8 Also srictly recommend not using tabs for indention. read here

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So, to summarize:

Pros:

• Have more space to arrange when wraping string more than 80 lines long.
• Can copy code from snippets and it just works.

Cons:

• With deeper level of nested statements you have less space for actual code.

Thanks.

Answer 1

Everyone else uses 4 spaces. That is the only reason to use 4 spaces that I've come across and accepted. In my heart, I still want to use tabs (1 indent character per indent, makes sense, no? Separate indent from other whitespace. I don't care that tabs can be displayed as different widths, that makes no syntactic difference. The worst that can happen is that some of the comments don't line up. The horror!) but I've accepted that since the python community as a whole uses 4 spaces, I use 4 spaces. This way, I can assemble code from snippets others have written, and it all works.

Answer 2

Identation and general coding style standards vary from language to language, project to project. There is one reason for adopting a coding style standard: so that the code look uniform, no matter who wrote it. That improves legibility in the project, and, to put it bluntly, it looks better.

There is one reason that is not valid when adopting a coding style standard: because you like it. Coding standards exists precisely because people's preferences vary, and if left to their own, chaos would ensue, to the detriment of all.

If you are writing code for yourself alone, which no one will ever read, go ahead and write it whatever you like. Otherwise, following the accepted standard of your community will make your code much more agreeable to everyone else's eyes. And remember, too, that if you DO decide to contribute code to a community in the future, you'll have an easier time if you are used to their coding style already.

As for changing the tab size, there are are many source code formatters out there which support Python, and most programmer's editors and IDEs also have this capability. You probably have it already, it's just a matter of consulting the documentation for the editor you are using.

Answer 3

It is easier to visually identify long nested code blocks with 4 spaces. Saves time when debugging.

Answer 4

Also one of reasons is: when you have some long line (longer than 80 symbols) and want to split it in 2 you will have only 1 space to indent, that is a bit confusing:

if code80symbolslong and somelongvariablegoeshere and somelongerthan80symbols \
 and someotherstatementhere:
  # some code inside if block
  pass

if code80symbolslong and somelongvariablegoeshere and somelongerthan80symbols \
  and someotherstatementhere:
    # some code inside if block
    pass

Answer 5

The PEP isn't the boss of you. If it's already consistently 2-space indented, there's no reason to change all your code to conform to it. You could follow it going forward if you really think it's that vital, but, frankly, I don't. You're better off going with whatever convention provides you (and your coworkers) the most comfort both in reading and writing.

Answer 6

If you're the only coder working on your source file and there are no coding standards that enforce a particular style, use whatever you're comfortable with. Personally (and in line with our coding standard), I use hard tabs so that whoever is looking at the code can use their own preference.

To make a change, you simply need to change all start-of-line spaces to ones that are twice as large. There are many ways to do this; in the Vim text editor, I can think of two: firstly:

:%s/^\(\s\{2}\)\+/\=repeat(' ', len(submatch(0))*2)

This is a simple regular expression that looks for one or more pairs of spaces at the start of the line and replaces them with twice as many spaces as were found. It can be extended to do all files by opening vim with:

vim *.py

(or the equivalent), followed by (untested):

:argdo %s/^\(\s\{2}\)\+/\=repeat(' ', len(submatch(0))*2)/ | w

Alternatively:

" Switch to hard tabs:
:set noexpandtab
" Set the tab stop to the current setting
:set tabstop=2
" Change all spaces to tabs based on tabstop
:retab!
" Change the tab stop to the new setting
:set tabstop=4
" Go back to soft tabs
:set expandtab
" Replace all the tabs in the current file to spaces
:retab

Of course, many other tools will offer similar features: I would be surprised if something like sed, awk, perl or python couldn't do this very easily.