On Fri, Nov 17, 2017 at 03:51:34PM -0200, Flavio Leitner wrote: > No functional change, just fixing coding style. > > Signed-off-by: Flavio Leitner <f...@sysclose.org>
I see from the thread that there's some controversy here. I think that there are two aspects to it: technical and nontechnical. Please allow me address them separately, starting with the technical side. The code that later evolved to become OVS originated in 2007 at Nicira. At the time, support for C99 features was far from universal among the compilers that seemed potentially important. Justin and I wrote the initial coding style document to emphasize portability. Therefore, originally it forbid any mid-block declarations as well as other features with limited portability (e.g. C++ style // comments). Since then there have been two relevant changes. First, C99 is becoming more pervasive across the compiler world. Second, it's become clear that OVS really only needs to care about three particular compilers, which are GCC, Clang, and MSVC, and all of these compilers now support C99 (and an increasing fraction of C11). As these changes have occurred, we have been evolving the OVS coding style too. Sometimes, the evolution has happened first in the coding style document (and later migrated to coding practice), and other times, it has happened in the code itself (and later migrated to the coding style document). I think that this slow co-evolution is natural, since it's rare for someone to go through all the code at once and update the style to match changes to the coding style document. Sometimes, OVS has only half-embraced new coding style features enabled by compiler advancements. Mid-block declarations are an example. I've been writing C code since 1992 or so (and I hope I'm getting better at it!) but I've only been able to rely on portable support for mid-block declarations for a few years. For better or for worse, when in 2014 Jarno proposed that we allow mid-block declarations in OVS, the fossil in me, not used to seeing mid-block declarations in C, made me reluctant. You can see that, originally, Jarno proposed simply allowing mid-block declarations in his message https://mail.openvswitch.org/pipermail/ovs-dev/2014-May/284130.html. In a reply, Ethan and I were the one who pushed back, with my "I'm still really nervous about this one (I think it often uglifies code)..." and Ethan's "...The reason is that most of the code doesn't do these things, and there's a value in consistency." Since 2014, I feel that the balance has shifted. We have increased the amount of code that uses mid-block declarations. My increasing familiarity with the style has reduced my misgivings, and even caused me to embrace them: I really like the reduced potential for use of uninitialized data by being able, far more often, to declare and initialize a variable at the same time. Most importantly for me personally, this save time in code review, since I spend less time flicking my eyes and scrolling my window back and forth between declaration and use to reassure myself that initialization precedes use. I still see some potential for ugliness, but the practical virtues of mid-block declarations usually outweigh them. What I'm saying here is, "I was wrong." I honestly forgot we had anything in the coding style document that discouraged mid-block declarations. I like consistency between code and documentation but I believe that the right thing to do here is to update the coding style document, by removing anything that discourages mid-block declarations. Now I use them pervasively and I want to encourages others to do so too. That's my long, rambling defense of mid-block declarations. The other technical issue here is about whether && and || should be at the beginning or end of a line. The coding style document, intentionally, does not take an explicit position on this, and I did not realize that the examples in the document are biased toward putting them at the beginning of the line. OVS uses a mix of positions. I personally tend to put them at the beginning of a line because I have a long history of writing code in the GNU coding style, which mandates this positioning, but others feel exactly the opposite (for example I believe that kernel style favors end-of-line positioning). This is a debate that frankly I don't care much for and I'd prefer to leave it as a matter to individual taste. (This is also why the coding style document gives some freedom in the positioning of /* and */ in comment blocks: there is a range of viewpoints on this and I think the answer doesn't matter.) If necessary, I favor adding an explicit statement to the document saying that lines may be split before or after binary operators. (On the other hand I do prefer ? and : at the beginning of a line.) I believe that there is also a nontechnical aspect here. I think that might take a different email to address. Let me see what I can do. _______________________________________________ dev mailing list d...@openvswitch.org https://mail.openvswitch.org/mailman/listinfo/ovs-dev
