Add build option to enable debug execution tracing

build.zig

@@ -36,6 +36,14 @@ pub fn build(b: *std.Build) void {
         .optimize = optimize,
     });
 
+    // Declare an option to build the program with debug statements
+    // (crafting interpreters: A virtual machine: execution tracing)
+    const executionTracing = b.option(bool, "tracing", "enable execution tracing") orelse false;
+    const options = b.addOptions();
+    options.addOption(bool, "tracing", executionTracing);
+
+    exe.root_module.addOptions("config", options);
+
     // This declares intent for the executable to be installed into the
     // standard location when the user invokes the "install" step (the default
     // step when running `zig build`).

src/main.zig

@@ -1,11 +1,15 @@
 const std = @import("std");
+const config = @import("config");
+
 const chunk = @import("./chunk.zig");
 const OpCode = chunk.OpCode;
 const VM = @import("./vm.zig").VM;
 
 pub fn main() !void {
     // Prints to stderr (it's a shortcut based on `std.io.getStdErr()`)
+    if (config.tracing) {
         std.debug.print("All your {s} are belong to us.\n", .{"codebase"});
+    }
 
     var mem = std.heap.GeneralPurposeAllocator(.{}){};
     const alloc = mem.allocator();