This example executes a process on the system, compile-time. This allows to run a git command git rev-parse HEAD and use its result as the value.
class Version { public static macro function getGitCommitHash():haxe.macro.Expr.ExprOf<String> { #if !display var process = new sys.io.Process('git', ['rev-parse', 'HEAD']); if (process.exitCode() != 0) { var message = process.stderr.readAll().toString(); var pos = haxe.macro.Context.currentPos(); haxe.macro.Context.error("Cannot execute `git rev-parse HEAD`. " + message, pos); } // read the output of the process var commitHash:String = process.stdout.readLine(); // Generates a string expression return macro $v{commitHash}; #else // `#if display` is used for code completion. In this case returning an // empty string is good enough; We don't want to call git on every hint. var commitHash:String = ""; return macro $v{commitHash}; #end } }
Usage
The function can be called like any other static function in Haxe.
// use as field @:keep public static var COMMIT_HASH(default, never):String = Version.getGitCommitHash(); // ..or trace to output trace(Version.getGitCommitHash());
