[webkit-dev] Proposing style guide change regarding braces on conditional arms

Peter Kasting pkasting at google.com
Fri Dec 4 13:58:39 PST 2009

On Fri, Dec 4, 2009 at 12:13 AM, Chris Jerdonek <chris.jerdonek at gmail.com>wrote:

> An alternative policy is as follows:
> (1) If-else control structures must have either braces around all
> clauses or braces around no clauses.
> (2) A clause with more than one line must be surrounded by braces.

This is actually the precise policy used by the Google C++ Style Guide,
which governs the Chromium repository.

The problem with this is that it fails to ensure consistency, and the
difference between consistently using braces everywhere and consistently not
using them on one-line bodies is significant enough that this comes up as a
bone of contention in code changes.

On Fri, Dec 4, 2009 at 6:30 AM, Adam Treat <treat at kde.org> wrote:

> It seems we keep changing the style guide as fashion changes.  It is meant
> to
> ensure consistency and readability.  This is a purely subjective change and
> I
> think unwarranted.

Obviously if I agreed I wouldn't have proposed this change, but it's worth
detailing why I disagree.  You mention that the style guide is meant to
ensure readability.  It seems clear, then, that you would support changes to
improve readability if they did not decrease consistency; the main problems
are that readability is significantly subjective (see some of the expressed
opinions in this thread), and changing the rules currently decreases
consistency (at least over the short to medium term).

I think safety and maintenance cost are also worth considering.  My opinion
is that this change (as well as Maciej's proposed variant) does not merely
affect readability but also improves safety very slightly.  (Requiring
braces at all times would improve safety more, and decrease maintenance
cost, but at perhaps some cost to readability.)

I agree with you that our codebase should be consistent.  Personally, I
would prefer that when we make style guide changes, we actually change the
codebase to comply with them.  Most of the work here could probably be
automated, and I think if we did this it would address the main concern you
have.  The counterargument to this is that it can obscure blame (probably
moreso for a change like the namespace indenting one than this change, but
noticeably in both cases).  On the other hand, gradual changes obscure blame
(gradually, at the changed locations) too, and it's already the case that
when digging up the history of a block of code you need to repeatedly skip
past uninteresting changes.

On Fri, Dec 4, 2009 at 9:39 AM, Adam Treat <treat at kde.org> wrote:

> I don't think we should be changing the style guide for anything besides
> clarifications of currently unwritten rules.  No matter how the fashion may
> change or how developers may change.  Changing the rules throws consistency
> out the window which is, I believe, the greatest benefit of having a style
> guide.

Again, I think the consistency argument would be addressed if we actually
made code consistent at rule changes.

Changing code to make it more readable by the current developer set, when
that developer set changes in makeup or opinion, seems like a good thing to
me, as it improves productivity and code quality, regardless of whether the
change is subjective in nature.  As an example I give you the SQLite
codebase, which has a consistent set of style rules that are so different
from any other code I have ever encountered that I struggle to read and
patch the code (and have been told the same by SQLite developers here at
Google).  You may argue that such a case is far outside any cognitive burden
of the rule in question in this thread, but tiny amounts of cognitive
friction, spread over a large codebase with many developers and a long
lifetime, add up.

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