Standardize tab width variables across major modes

Standardize tab width variables across major modes

[Andrew Pennebaker]

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Many Emacs modes seem to obey tab-width, e.g. (setq-default tab-width 2).
But a few modes define their own variables for this:

* JavaScript https://github.com/mcandre/dotfiles/blob/master/.emacs#L251
<https://github.com/mcandre/dotfiles/blob/master/.emacs#L250>
* CSS https://github.com/mcandre/dotfiles/blob/master/.emacs#L252
* Python https://github.com/mcandre/dotfiles/blob/master/.emacs#L256
* Rust https://github.com/mcandre/dotfiles/blob/master/.emacs#L262
* Go https://github.com/mcandre/dotfiles/blob/master/.emacs#L266
* Erlang https://github.com/mcandre/dotfiles/blob/master/.emacs#L274
* Haskell https://github.com/mcandre/dotfiles/blob/master/.emacs#L277
* PostScript https://github.com/mcandre/dotfiles/blob/master/.emacs#L284
* Mozart/Oz https://github.com/mcandre/dotfiles/blob/master/.emacs#L287

Could we refactor these modes to use the standard variables
tab-width, indent-tabs-mode, and sws-tab-width? We can maintain backwards
compatibility by continuing to offer nonstandard variables
like js-indent-level, by deriving them from the standard variables.

... could we refactor sws-mode to derive sws-tab-width from tab-width?

-- 
Cheers,

Andrew Pennebaker
www.yellosoft.us

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Re: Standardize tab width variables across major modes

[Stefan Monnier]

> Many Emacs modes seem to obey tab-width, e.g. (setq-default tab-width 2).
> But a few modes define their own variables for this:

You then go on to describe something else than tab-width (which is the
display size of a TAB character in the buffer), namely the size of the
default indentation step.

Those two things are very different.

The default indentation step depends on the indentation style, which
tend to vary between languages (even for a single individual).

This said, I agree that we should try and standardize the "default
indentation step" variable used by the various major modes.

`smie-indent-basic' was kind of meant to be this, but it's pretty
difficult to combine the need to obey the old variable's name.


        Stefan