Not to be too much of a stickler, but #pragma once is a bit strange. It runs slightly counter to:
The ‘#pragma’ directive is the method specified by the C standard for providing additional information to the compiler, beyond what is conveyed in the language itself. I suppose a directive that says "skip this file under certain conditions" is "beyond what is conveyed in the language itself". The problem is that code that compiles fine with the pragma could fail (fairly easily) without, which doesn't seem to be the intent of pragmas. But conceptually, it does seem like a better solution. Of course, compliers aren't obligated to support it, so any compiler that probably won't work. It probably doesn't matter much, but IBM's commercial XL C/C++ compiler doesn't support this per the venerable Wikipedia. -John On Tue, Jan 20, 2015 at 6:08 PM, Kapil Arya <[email protected]> wrote: > On Tue, Jan 20, 2015 at 6:00 PM, Benjamin Hindman <[email protected]> > wrote: > > > What's the rush on committing this? Let's make sure all of the committers > > get a chance to share their opinion on this please. > > > > This was assuming that most people would agree on the change. However, if > that's not the case, then there is no hurry :-). > > > > I for one would love to hear from others that have used #pragma once in > > practice and hear any pros/cons from them. > > > > Also, while the > > to >> change was meant to preserve some information, > > I'm not convinced that there is any information to preserve by replacing > > all include guards with #pragma once, and otherwise I feel like we're > going > > to get just as many reviews where people have to tell you to switch to > > #pragma once rather than appropriately name the include guard. > > > > Good point. In this case, we can just do a mass update (if we agree to the > change). > > > > > On Tue, Jan 20, 2015 at 5:04 PM, Kapil Arya <[email protected]> wrote: > > > > > Hi All, > > > > > > This issue came up on several occasions. Since people seem to agree on > > > using "#pragma once" instead of "#define" guards that we have using, I > > > wanted to send a quick email to gather some consensus around it. If > > > everyone agrees about the switch, we can update the style guide and > start > > > using "#pragma once". > > > > > > The issue is tracked at > https://issues.apache.org/jira/browse/MESOS-2211 > > > and there is a review request at https://reviews.apache.org/r/30100/. > > > > > > Please note that this won't be a mass update. We should keep updating > the > > > files that are created/updated (similar in spirit to "> >" to ">>" > > change). > > > > > > If there are any concerns, please let us know. We would very much like > to > > > commit this by tomorrow and any feedback before that is highly > > appreciated. > > > > > > Best, > > > Kapil > > > > > >
