Seems like we have an informal consensus: I update the style guide to reflect this: https://cwiki.apache.org/confluence/pages/viewpage.action?pageId=65868536
On Thu, Aug 2, 2018 at 3:22 AM, Zoltan Borok-Nagy < borokna...@cloudera.com.invalid> wrote: > +1 for #pragma once since it's cleaner and less error-prone. > > Zoltan > > > On Wed, Aug 1, 2018 at 11:03 PM Todd Lipcon <t...@cloudera.com.invalid> > wrote: > > > Yea, when we looked into it I recall that it worked fine on all compilers > > from the last 10 years or something (in fact I remember using #pragma > once > > on Metrowerks Codewarrior more than fifteen years ago). Given we require > > C++14 I don't think #pragma once is going to be the limiting factor in > > compiler version portability. > > > > -Todd > > > > On Wed, Aug 1, 2018 at 12:01 PM, Sailesh Mukil > > <sail...@cloudera.com.invalid > > > wrote: > > > > > An advantage of using #pragma once is potential improved compilation > > > speeds. However, a con is that it's non-standard and therefore, its > > > behavior can change at any point and can also vary across compilers, > > > potentially making the code even less portable. > > > > > > That being said, since Kudu has been using it for a while and has had > no > > > issues, we can do the same since the potential benefits outweigh the > > cons. > > > > > > On Wed, Aug 1, 2018 at 11:48 AM, Tim Armstrong < > > > tarmstr...@cloudera.com.invalid> wrote: > > > > > > > Todd brought up our include guards on a code review, asking why we > > don't > > > > use #pragma once instead: https://gerrit.cloudera.org/#/c/10988/5 . > It > > > > sounds like Kudu has switched to it > > > > > > > > #pragma once does seem cleaner and our GCC and Clang versions are > > modern > > > > enough to support it. > > > > > > > > What do people think about switching to that as the preferred way of > > > > including headers only once? > > > > > > > > - Tim > > > > > > > > > > > > > > > -- > > Todd Lipcon > > Software Engineer, Cloudera > > >
