Always spaces, never tabs

Objective arguments that decided my personal preference.

published 2020-Oct-23, updated 2024-Feb-16

TLDR: always spaces, never tabs; 2 spaces rather than 4.

Arguments

Objective arguments in favor of spaces over tabs:

• Spaces are both necessary and sufficient. Tabs are not necessary and not sufficient (imagine separating words with tabs). Adding them adds complexity.
• Tabs break when copy-pasting. For example, some terminals and websites render tabs as spaces, usually as 8.
• Distinguishing tabs from spaces requires special editor support. (Rendering special whitespace symbols.)
• Mixing tabs with spaces causes indentation to break in different editors. People will mix them. Plenty of languages and editors don't have autoformatters. It will always stay this way.

Objective arguments in favor of tabs:

• Configurable visual indentation level.
• Fewer characters. Sometimes fewer keystrokes. (Note: in decent code editors, using spaces takes just as many keystrokes.)

Objective arguments in favor of 2 spaces over 4 spaces:

• Fewer characters and keystrokes.
• Easier to type in non-specialized editors, such as chat input boxes, which don't have indentation shortcuts.
• Highly-nested code fits better on the screen. Relevant for markup such as XML.

Objective arguments in favor of 2 spaces over 1 space:

• Easier to distinguish from line wrapping. In some editors, when line wrapping is enabled, the secondary lines are intended by 1. With 2-space indentation, you can tell them apart.

Bias

Your preference is influenced by your display pixel density, resolution, OS, font family, font size, eyesight, and habits. Someone with a very large but low-DPI display is likely to prefer 4 spaces. Someone who writes code on a small display, in an IDE that uses 20% of the screen area for the actual code, is likely to prefer 2 spaces.

If you don't have a strong preference, 2 spaces seems like a better default, based on the arguments above.