I'm trying to get rid of tabs, following this guide:
(setq-default indent-tabs-mode nil)
So: why setq-default and not setq? I know I would need to use setq-default for a buffer-local variable, but I can't actually determine (except from inferring from the guide) whether indent-tabs-mode is buffer local.
C-h v return something more confusing to me:
Automatically becomes buffer-local when set.
So it would become buffer local if I setq it, so I must setq-default it?
When you see Automatically becomes buffer-local when set you can rely on it meaning just what it says: whenever that variable is set (e.g., using setq), it becomes buffer-local if it was not already buffer-local. So yes, setq sets the buffer-local value, and if you want to set the global, default value then you need to use setq-default.
emacswiki says: "You should ensure these variables have the same value, e.g., (setq tab-width..." That certainly can be interpreted in different ways. One of which is: "Use setq for tab-width, but setq-default for indent-tabs-mode" Which I assume to be wrong. Do you have any clues why they use setq for tab-width?
setq-default to set the global value, and setq to set a buffer-local value (assuming that the variable is buffer-local.
indent-tabs-mode is set using setq-default, but tab-width is set using just setq. Do you have any clues why that is so? Both of them are buffer-local, as far as I can tell. Why not set both of them with setq-default?
indent-tabs-mode everywhere, by default. The second is in the context of "The rest of this page will assume tabs are used..." It is telling you how to deal with particular modes that allow the use of tab chars, i.e., buffers that overrule the default of using only spaces as set by the setq-default of indent-tabs-mode. To be clear, I didn't write that page, and I'm no expert on any of this. My reading of it is that it is telling you (a) how to turn off using tabs, by default and (b) how to allow tabs in some buffer/mode.
To find out if variable is buffer-local use:
(local-variable-p 'name-of-variable) see docs.
indent-tabs-mode, sosetq-defaultis not a 100% guarantee that your buffer will have said default setting. Only if nothing else sets that variable differently when using a particular combination of major-mode and minor-modes would that default setting be respected. Thus, it may be necessary to use a major-mode hook to set the variable to your liking. Here is link to a recent example where thetab-widthis set by a major mode to4and a major-mode hook is used to reset the value to2. emacs.stackexchange.com/a/10329/2287