Add mechanism for using custom global version instead of lune-std crate version

crates/lune-std/src/globals/version.rs

@@ -2,7 +2,34 @@ use mlua::prelude::*;
 
 use lune_utils::get_version_string;
 
+struct Version(String);
+
+impl LuaUserData for Version {}
+
 pub fn create(lua: &Lua) -> LuaResult<LuaValue> {
-    let s = get_version_string(env!("CARGO_PKG_VERSION"));
+    let v = match lua.app_data_ref::<Version>() {
+        Some(v) => v.0.to_string(),
+        None => env!("CARGO_PKG_VERSION").to_string(),
+    };
+    let s = get_version_string(v);
     lua.create_string(s)?.into_lua(lua)
 }
+
+/**
+    Overrides the version string to be used by the `_VERSION` global.
+
+    The global will be a string in the format `Lune x.y.z+luau`,
+    where `x.y.z` is the string passed to this function.
+
+    The version string passed should be the version of the Lune runtime,
+    obtained from `env!("CARGO_PKG_VERSION")` or a similar mechanism.
+
+    # Panics
+
+    Panics if the version string is empty or contains invalid characters.
+*/
+pub fn set_global_version(lua: &Lua, version: impl Into<String>) {
+    let v = version.into();
+    let _ = get_version_string(&v); // Validate version string
+    lua.set_app_data(Version(v));
+}

crates/lune-std/src/lib.rs

@@ -7,6 +7,7 @@ mod globals;
 mod library;
 
 pub use self::global::LuneStandardGlobal;
+pub use self::globals::version::set_global_version;
 pub use self::library::LuneStandardLibrary;
 
 /**