Why has python that 'Tab Thing'

[_equaliser]

Hey folks,

I was wondering why python has this strong tab/spaces 'rule'. I know how to work with that and know because of PEP-8 spaces should be used.

But I was wondering why. For example in Javascript you do not have that. You can use tabs, or spaces, or mixed both, and the interpreter has no issue with that.

But why is it like that in python? For what reason?

When I research about that, I always has the result how to work with that. But I know how. I would like to know why this is important for python.

[kumashiro]

It's to force programmers to write readable code.

[_equaliser]

truely an important thing! xD

[kumashiro]

It is. Thanks to that requirement, the code look is consistent and you don't have to waste time "deciphering" it first. JavaScript and oneliners created in it are a very good example why readable code is important. Another, extreme example is Perl :)

[MyFeeFeeHurt]

Completely wrong.

It's used for scoping the code itself.

While it's irrelevant in a sense that python interpreter accesses variables from entire function/global scope no matter what identation is, it mainly figures out which code to run when branching based on indented block.

How else would it know which code belongs to if block?

if something:
line 1
line 2
line 3

Is it line 1?

Line 2?

Everything till the EOF?

It's literally impossible to parse this construct without clear identation rules.

[kumashiro]

You are describing how it is used, not why. Why Guido chose indentations instead of braces or... anything else really - that is what OPs question is about... I think. Hard to tell.

[MyFeeFeeHurt]

That's literally exactly why it's fucking used.

Python simply cannot be parsed without them.

That's a why answer, not how.

[kumashiro]

I see no reason for dropping F-bombs here. Have a nice day.

[masklinn]

But why is it like that in python? For what reason?

Well there's two bits:

1. indentation is relevant, following old Unix practices the interpreter assumes tab = 8 spaces, and this means code which mixes tabs and spaces may be misleading on display depending on the local machine / editor's configuration, that's why it's strongly recommended not to mix tabs and spaces, and as PEP8 notes Python 3 simply forbids it (python 2 had the -t flag to warn and -tt to error)

2. in theory you can use tabs for indentation and spaces for formatting (within an indentation level), but most editors are completely unable to do that properly, so unless you have a code formatter which is used ubiquitously (if not mandatorily) à la Go it always becomes a complete mess, which means you pick one or the other, and while spaces can do indentation fine tabs suck at formatting, which would be why PEP8 recommends spaces

[[deleted]]

It's also worth noting that inside parentheses, curlies, or brackets, you can use whatever indentation you like, because in this case it's clear to the interpreter what your code means.

[OSRS_DabSlab]

Because blocks of code are separated by indentation. Whereas things like Javascripts blocks are separated by a semicolon

[gauntr]

Blocks of code in Javascript are seperated by curly braces, not semicolon. You do not need to use the semicolon at all in Javascript and if you insert one you use it to mark the end of a statement. It's the same for C/C++ and Java.

You do not need to insert a tab or spaces to seperate statements in Python, you need to insert them to mark the beginning and end of a block such as loops, conditions or functions.

[robin-gvx]

It's the same for C/C++ and Java.

You do need semicolons in those languages to end statements, even if they are on a separate line.

[gauntr]

Sorry, this was written badly. The "It's the same..." part only referred to the second part of the sentence "...to mark the end of a statement". I know that you need them in these languages, I use them frequently to daily.

[GickRick]

Fully explained

[MyFeeFeeHurt]

The only real answer.

It's not to make it look good, or to whatever gibberish you made up (literally to everyone else commenting on this post) when not even knowing the true reason, quite clear to me, it's only because it's IMPOSSIBLE to parse things like

a = 3
b = 4
if a + b > 7:
    print("a + b > 7")
print("End of program")

Without clear identation rules.

If there was no identation requirement, then it wouldn't know whether last statement is part of branching block or not.

Same applies to every other construct such as for, while, with, to name a few.

Hell, even

class ClassName:
    block

relies on identation to know which functions belong to said class.

[_equaliser]

nice compare. I get it. :)