Update cc-style to use a mix of tabs and spaces, depending on context?

Question

I'm looking for a way to mix tabs and spaces in my cc-styles.

Whilst I question the sanity of this coding style, and wouldn't ever choose to use it had I the choice (seems other people share my view), in this instance I don't have a choice.

My company has the following coding style wrt tabs and spaces:

• Indentation should be made using tabs
• Alignment should be made using spaces

As an example, with -> denoting a tab, the following are valid snippets:

tabs for indentation, spaces for vertical alignment of variable names and initialisation:

struct Foo
{
-> int    bar  = 0;
-> char   baz  = 'c';
-> double fizz = .1;
};

tabs for indentation, spaces for vertical alignment of function parameters:

void some_function(int foo,
                   double bar,
                   char baz)
{
-> if (foo == 0)
-> {
-> -> bar *= 2;
-> }
-> ...
}

tabs for indentation, spaces for vertical alignment of logical statements:

void some_function(int foo,
                   double bar,
                   char fizzbuzz)
{
-> if (foo      == 0 &&
->     fizzbuzz == 'a') // note 1 leading tab for indentation level, then spaces
-> {
-> -> bar *= 2;
-> }
-> ...
}

I use the align package by John Wiegley in order to affect the vertical alignment of variables in the example above.

What do I need to have in my cc-styles in order to conform to my company's coding standards?

Answer 1

Smart Tabs is a mode that will do what you want -- indent with tabs, align with spaces.

From the documentation, once you install it, you can disable it normally, but enable it in c-mode this way:

(setq-default indent-tabs-mode nil)

(add-hook 'c-mode-common-hook
          (lambda () (setq indent-tabs-mode t)))