Version blocks

Version blocks are a cleaner alternative to #ifdef in C.

They allow you to write platform-specific code. It’s almost always a bad thing to have to maintain several separate codebases, each for one platform. Version blocks allows you to have the code for all platforms in one case.

Syntax

version-block ::=  "version" "(" <version-expr> ")" "{" <block> "}"
version-expr  ::=  <version-name>
version-expr  ::=  "(" <version-expr> ")"
version-expr  ::=  "!" <version-expr>
version-expr  ::=  <version-expr> && <version-expr>
version-expr  ::=  <version-expr> || <version-expr>

Examples

Here are some examples of combinations of version-expr:

version(linux) {
    println("Got Linux\n")
}
version(!linux && unix) {
    println("Got another unix")
}
version(!linux && (unix || windows)) {
    println()
}

Built-in version-names

windows -> (__WIN32__ || __WIN64__)
linux   -> __linux__
solaris -> __sun
unix    -> __unix__
beos    -> __BEOS__
haiku   -> __HAIKU__
apple   -> __APPLE_
gnuc    -> __GNUC__
i386    -> __i386__
x86     -> __X86__
x86_64  -> __x86_64__
ppc     -> __ppc__
ppc64   -> __ppc64__
64      -> (__x86_64__ || __ppc64__)

If you use another name, it will write it as-is in the #ifdef, which means you can add your own typedefs if you want. (E.g. pass them with +-DYOURTYPEDEF=1 if you’re using gcc)

Imports

There will be support for imports in version blocks soon. Meanwhile, your best bet is to have an abstract class that contains the interface you want to expose, and to subclass it for each platform.

Then use the Factory pattern and return the right subclass depending on the platform.