On Thursday 13 April 2006 11:01, "Kevin O'Gorman" <kogorman@gmail.com> 
wrote about 'Re: [gentoo-user] [OT] vim c syntax':
> set expandtab

Converting tabs to spaces or vice-versa automatically is evil.  They have 
distinct uses so just don't do it.

Tabs are used to indicate separate "levels" of text where items are or can 
be nested and are appropriate for use in tables of contents (subsection 
titles have one more tab than section titles, section titles have one more 
tab than chapter titles, etc.), lists (numbered or bulletted), block 
quotation (imagine quoting an article that had quoted a speech), and the 
nested block structure of many programming languages.

In addition their the language-specific roles, spaces are used to align 
arbitrary text, tabs alone are inappropriate because of the varying tab 
settings on varying computers.  Even if 8 spaces was some kind of 
standard, it makes very little sense in non-fixed-width fonts, and trying 
to force end-user behavior is both arrogant and doomed to failure.  
(That's not what standards are about anyway -- standards give the 
end-user/consumer MORE choice by forcing programmer/producer OUTPUT to be 
interchangeable.)

Tabs and spaces together can also be used for alignment, and when done 
properly the output changes based on the end-users preferences but looks 
good independent of those preferences.  How this is done is left as an 
exercise to the reader.

Tabs w/o spaces can only be used for alignment when the file format you are 
dealing with allows you to embed information about what tab-stops you are 
using.  (Thus, ignoring the users' preferences entirely.)

> set shiftwidth=4        " sw, number of spaces shifted left and right

This is all the OP needed to get the behavior he wanted.

For completeness, here's the relevant lines of my .vimrc:
set ts=2 " Small tabs
set sw=2 " Matching shift width
set list " Visible tabs

set ai " Auto-indent
set si " Smart indent
(I like my tabs /tiny/.)

-- 
"If there's one thing we've established over the years,
it's that the vast majority of our users don't have the slightest
clue what's best for them in terms of package stability."
-- Gentoo Developer Ciaran McCreesh