On Wed, Apr 8, 2020 at 4:13 PM Tom Payne <twpa...@gmail.com> wrote: > > Go allows OS-specific code to be selected two different ways, either using > the runtime.GOOS constant or with file-level build tags like "//+build linux" > or (equivalently) OS-specific source file suffixes like _linux. > > What's the recommended way to decide when to use which? > > As far as I can tell: > - There is no runtime advantage to either. runtime.GOOS is a constant, so the > compiler eliminates any unreachable branches. File-level build tags mean that > irrelevant files don't even reach the compiler. Either way, the irrelevant > code is not included in the final binary and incurs no runtime cost. > - When using build tags, the fact that irrelevant code doesn't reach the > compiler means that errors can creep in. For example, compile errors in > foo_linux.go will be unnoticed if you only ever compile on Windows. In > contrast, using runtime.GOOS will mean that compile errors are found whatever > OS you compile on. > - Only build flags and OS-specific source file suffixes give you control over > imports. > > Therefore, it would seem that the recommendation of when to use runtime.GOOS > vs. build flags/file suffixes is: > - Use runtime.GOOS unless you need OS-specific imports or your OS-specific > code is so different that it really deserves to be in a separate source file. > > Is this recommendation reasonable? What could be improved?
What you say sounds right to me. I would just add that code that tests runtime.GOOS a lot can be hard to follow. So another reason to use a separate file is to avoid having to write a lot of potentially confusing if statements. Also I'll note that Go's cross-compilation support makes it straightforward to write tests that ensure that OS-specific code continues to compile. Ensuring that the code continues to work correctly is admittedly more difficult. Ian -- You received this message because you are subscribed to the Google Groups "golang-nuts" group. To unsubscribe from this group and stop receiving emails from it, send an email to golang-nuts+unsubscr...@googlegroups.com. To view this discussion on the web visit https://groups.google.com/d/msgid/golang-nuts/CAOyqgcWGsG_VMSun0BcsaLzoaOMZoFRRX_7yYqq58Qf9rUz7kQ%40mail.gmail.com.
