Handling Operating System Variation

When writing cross-platform applications or libraries, it is often necessary to allow for differences between operating systems. The variableSys.KERNEL can be used to handle such cases. There are several functions in theSys module intended to make this easier, such asisunix,islinux,isapple,isbsd,isfreebsd, andiswindows. These may be used as follows:

if Sys.iswindows()    windows_specific_thing(a)end

Note thatislinux,isapple, andisfreebsd are mutually exclusive subsets ofisunix. Additionally, there is a macro@static which makes it possible to use these functions to conditionally hide invalid code, as demonstrated in the following examples.

Simple blocks:

ccall((@static Sys.iswindows() ? :_fopen : :fopen), ...)

Complex blocks:

@static if Sys.islinux()    linux_specific_thing(a)elseif Sys.isapple()    apple_specific_thing(a)else    generic_thing(a)end

When nesting conditionals, the@static must be repeated for each level (parentheses optional, but recommended for readability):

@static Sys.iswindows() ? :a : (@static Sys.isapple() ? :b : :c)