[U-Boot] [PATCH v4 0/8] Provide a mechanism to avoid using #ifdef everywhere

[Tom Rini]

On Mon, Oct 28, 2013 at 03:44:01PM +0100, Wolfgang Denk wrote:
> Dear Simon,
> 
> In message <1382800457-26608-1-git-send-email-sjg at chromium.org> you wrote:
> > Many parts of the U-Boot code base are sprinkled with #ifdefs. This makes
> > different boards compile different versions of the source code, meaning
> > that we must build all boards to check for failures. It is easy to misspell
> > an #ifdef and there is not as much checking of this by the compiler. Multiple
> > dependent #ifdefs are harder to do than with if..then..else. Variable
> > declarations must be #idefed as well as the code that uses them, often much
> > later in the file/function. #ifdef indents don't match code indents and
> > have their own separate indent feature. Overall, excessive use of #idef
> > hurts readability and makes the code harder to modify and refactor. For
> > people coming newly into the code base, #ifdefs can be a big barrier.
> 
> While I agree in general with the goal and the implementation, there
> is an implementation detail I dislike - this is that the new code
> is harder to type and to read - I mean, something like
> CONFIG_SYS_HUSH_PARSER is already clumsy enough, but making this
> autoconf_sys_hush_parser() appears to be worse.  Also, the connection
> to a CONFIG_* option is not easily visible.
> 
> 
> I also had feedback from Detlev (who is unfortunately on a business
> trip again so he didn't find time [yet] to comment himself); he
> commented that he really likes the idea, but does not like that we now
> have to access the well-known contants using a new name.
> 
> 
> Maybe we can find a shorter / easier to read way to do this - I think
> it would be really nice if we could see the well-known names.

I guess this is what I get for not being like Linus sometimes[1].  I think
what this series highlights is that we have a lot of code in
common/main.c that needs either re-thinking, re-factoring or splitting
out into difference functions and files.  And when we're turning
#ifdef CONFIG_FOO
	... whatever ...
#endif
into
	if (autoconf_foo()) {
		... whatever ...
	}

The code starts looking worse in some cases since we're already 3
indents in.  The problem is we have lots of ifdef code, in some areas of
the code.  This hides the problem, not fixes the problem.

Looking over the first parts of the series, weak functions for example
would help in a number of cases, especially if we split things out of
main.c and into other files too.

-- 
Tom

[1]: By which I mean being very "forceful" when saying I don't like an
idea.
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