Indenting with white spaces, tabs, and how many spaces or the tab width [closed]_问答_开发者

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I know that this is more of a coding style, instead of a one right way of doing things. But, I'm a bit frustrated if I came across different indenting formats.

But, I would like to hear the reasons by various people on these issues:

Do you use spaces or tabs? Tabs with spaces? Any difference with "Tab insert space", instead of using the space key directly?
How many spaces to indent each line of code? Why?
Does different code has different style that is more suitable for each of them?

Is there a way to "visually" indent code without actually writing the indent? So it won't ruin the original indenting? It seems unlikely.

I'm using Xcode, so it's better if you have advice for Xcode projects.

You should always use the coding style that the project is already using if you are modifying an existing project.

That being said, if you are able to choose your own coding style for a new project I suggest that you use tabs to indent code and not spaces -- here is why. By using spaces you force all of the other developers working on the project to conform to your indentation preference whether that be 2 spaces or 4 or 8 (or whatever). But by using tabs each developer can view the code using their own preference. You should uses spaces and not tabs to format text (to line up variable names one per line, or to line up multi-line comments) because that will work with any tab width preference. However, when you indent code use tabs not spaces. In short, indent with tabs because indenting with spaces is rude.

spaces because they render the same everywhere
indent-width is context-dependent. runaway indentation is bad. generally, languages where you cannot easily reset the indentation to sane levels through named abstraction items (functions or methods) need narrow indentation.
yes, see previous bullet

the claim that tabs allow individual developers to use different tab widths is false. consider

typedef __LA_SSIZE_T archive_write_callback(struct archive *,
                                            void *_client_data,
                                            const void *_buffer,
                                            size_t _length);

if this was produced with tabwidth of 2, it would look like this with tabwidth = 4:

typedef __LA_SSIZE_T archive_write_callback(struct archive *,
                                                                                        void *_client_data,
                                                                                        const void *_buffer,
                                                                                        size_t _length);

conversely, if it was produced with tabwidth = 8 and displayed with tabwidth = 4, the result would be

typedef __LA_SSIZE_T archive_write_callback(struct archive *,
                        void *_client_data,
                        const void *_buffer,
                        size_t _length);

so if a project style guide requires tabs and says function parameters need to align as in the first code display, then there's a single correct tab width.

(another answer presents the same argument.)

a long-overdue edit:

i wholeheartedly agree with the opening sentence of the accepted answer, which is

You should always use the coding style that the project is already using if you are modifying an existing project.

the rest of that answer is, excuse me, rubbish, and i tried to explain why above.

the question of indentation style should only come up at the very beginning of any project, once it's settled it's done. i do believe that spaces are better than tabs, and have (again, i believe) rational arguments in support of my position, etc. but i'm not going to start discussions on this topic because they're useless: most programmers i met support their preferences with irrational arguments, and the rest have settled for a style which works best with their tooling (like me: "spaces because they render the same everywhere"), which i have no influence over in general.

anecdote: i once worked on a project which underwent a change of newlines, from \r\n to \n, and it turned out to be a pain in the ass any time we needed to go past the revision in svn blame. s/newlines/indentation/, and you have a nice argument against massive indentation changes in a running project.

An advantage to spaces vs tabs is alignment when wrapping long lines. If you use tabs, no matter what you do, the lines below will most likely not align, unless the editor has the same settings.

For example:

    result = variable_one + variable_two + variable_three +
             variable_four;

If you use tabs, how to ensure that 'variable_four' will show up aligned if tab indentation changes?

There are different programming languages with very different syntax. The syntax is crucial in choosing a coding style. Especially the tab size (number of spaces) that you will chose will depend on how many levels you need to have. In HTML for instance there are many levels, and there it makes no sense to have a big tab size, it even makes no sense in using tabs.. you just use spaces. Another very important aspect is the IDE you use. In some IDE's you are encouraged to use tabs (in Visual Studio you have the nice facility to add/remove tabs to more than one line (TAB to add, SHIFT+TAB to remove) and so on. Projects have different indent sizes because people use different indent settings (even in the same code) or because they use different editors or because the project includes code from other projects or even simply because people have different preferences or even different sized monitors. I work in Visual Studio C++ and VB.NET, indent is tab based(3 lines) and tabs do not insert spaces.

I simply use the defaults of the editor I'm currently working in, but if I have the choice I use tabs because it means less invisible characters to manage. I have one editor that wholly manages indentation for me (REALbasic), another editor that manages indentation for me, allows for spaces as prefix but formatting gets wonky if I leave them in (Applescript), and there's Xcode.
I see 4 spaces more than another number for space-based indentation, so I go with that if I have to.
I've found that every community more or less has a standard that has been placed in example code, so I just go with that otherwise tabs then 4 spaces. Simple.

Honestly, I gave up on the indentation fight a long time ago and expend my brain power on other, what I feel are more important, code-related issues like good variable and functions names. Any reasonable code editor can help you manage poorly-placed or complex indentation but none of them can help with sorting out poorly-written or complex code.

Depending on your IDE and your "tab inserts spaces" option, it's a nice shortcut over using the spacebar. I.e. at 3 indentation levels with 3 spaces per tab, you press the Tab key 3 times instead of the spacebar 9 times. The net effect is the same - you inserted 9 spaces - but with 1/3 the number of keystrokes.

A benefit of using spaces instead of tabs can make printing your code a bit nicer, especially if you're using a non-typewriter style font. I usually use a width of 3 spaces for each 'level' of indentation.

Because I prefer proportional fonts at a specific 15pt size, I set a TAB to be 37 pixels.

I don't mind that you use FOUR SPACES as long as you also use a font where a SPACE is 37/4 pixels wide. Or TWO SPACES as long as you also use a font where a SPACE is 37/2 pixels. Or even THREE SPACES, as long as you also use a font where a SPACE is 37/3 pixels.

Otherwise, a TAB works great for both us.