keyboard shortcuts - Why might my Emacs use spaces instead of tabs?

Question

I am trying to diagnose this problem. TAB creates 4 spaces instead of a 4 col TAB like I want. But I don't think it should because C-h v indent-tabs-mode on the buffer in question says it is set to t. When I check my keybindings, TAB is set to c-indent-line-or-region. Does this function ignore my tabs-mode?

Answer 1

Tabs and indentation in Emacs is a considerably more complex subject than most people anticipate. I highly recommend spending some time reading about it -- it will almost certainly save you some confusion in the long run.

The following page at the Emacs Wiki groups together most of the relevant discussion: http://www.emacswiki.org/emacs/CategoryIndentation

There's quite a lot there, but it's worth looking through.

One or other of the TabsAreEvil and SmartTabs configurations is quite likely to be appealing to you, btw, depending on your personal opinions on the subject!

Make sure you read the page on the tab-stop-list variable. It's tucked away near the bottom of that list of links, but it's critical to understanding the behaviour of tabs in the absence of automated-indentation rules, along with things like 'tabify'.

ruler-mode is useful here as well. I enable it automatically with text-mode:

;; Use ruler in text-mode
(add-hook 'text-mode-hook
          (function (lambda ()
                      (setq ruler-mode-show-tab-stops t)
                      (ruler-mode 1))))