Make result errors throw lua error rather than panic and crash

Fixes #10

Author: vurvdev

examples/engine/src/lib.rs

@@ -9,7 +9,7 @@ fn get_iface() -> Option<&'static EngineClient> {
 #[lua_function]
 fn concmd(l: LuaState) -> i32 {
 	if let Some(iface) = get_iface() {
-		iface.ExecuteClientCmd( luaL_checklstring(l, 1, 0) );
+		iface.ExecuteClientCmd( luaL_checkstring(l, 1) );
 	}
 	0
 }

examples/exception/Cargo.toml

@@ -0,0 +1,13 @@
+[package]
+name = "gmod_exception"
+description = "Binary module to display exception handling with rglua"
+version = "0.1.0"
+edition = "2021"
+publish = false
+
+[lib]
+crate-type = ["cdylib"]
+
+[dependencies]
+rglua = { path = "../../rglua" }
+thiserror = "1.0.30"

examples/exception/src/lib.rs

@@ -0,0 +1,41 @@
+use rglua::prelude::*;
+
+#[derive(Debug, thiserror::Error)]
+enum ResultError {
+	#[error("Number was negative!")]
+	Negative,
+	#[error("Number greater than 5!")]
+	Catastrophic
+}
+
+#[lua_function]
+fn result(l: LuaState) -> Result<i32, ResultError> {
+	let num = luaL_checkinteger(l, 1);
+
+	if num > 5 {
+		return Err( ResultError::Catastrophic )
+	} else if num < 0 {
+		return Err( ResultError::Negative )
+	} else {
+		lua_pushinteger(l, num);
+		return Ok(1)
+	}
+}
+
+#[gmod_open]
+fn open(l: LuaState) -> i32 {
+	printgm!(l, "Loaded exception module!");
+
+	let lib = reg! [
+		// "panic" => panic, (Soon™️)
+		"result" => result
+	];
+
+	luaL_register(l, cstr!("except"), lib.as_ptr());
+	0
+}
+
+#[gmod_close]
+fn close(_l: LuaState) -> i32 {
+	0
+}

rglua-macros/Cargo.toml

@@ -1,7 +1,7 @@
 [package]
 name = "rglua-macros"
 description = "Procedural macros to be used with rglua"
-version = "0.1.0"
+version = "0.2.0"
 authors = ["Vurv <[email protected]>"]
 keywords = ["glua", "garrysmod", "lua", "gmod"]
 categories = ["api-bindings", "external-ffi-bindings", "development-tools::ffi", "game-development", "accessibility"]

rglua-macros/src/lib.rs

@@ -79,8 +79,18 @@ fn handle_gmod(item: TokenStream, export: Option<&str>) -> TokenStream {
 				#(#inner_stmts)*
 			}
 		};
+
 		let resultant = quote! {
-			return #inner_fn(#lua_shared_param).unwrap();
+			match #inner_fn(#lua_shared_param) {
+				Err(why) => {
+					// Your error must implement display / .to_string().
+					// I'd recommend ``thiserror``.
+					let err = why.to_string();
+					let err = cstr!(err);
+					rglua::lua::luaL_error(#lua_shared_param, cstr!("%s"), err.as_ptr());
+				},
+				Ok(n) => { return n }
+			}
 		};
 
 		ast.block

rglua-macros/tests/base.rs

@@ -4,6 +4,15 @@ use rglua_macros::{gmod_close, gmod_open, lua_function};
 #[derive(Debug)]
 enum LuaError {}
 
+
+// The errors you return must implement display, to be relayed to gmod.
+use std::fmt::{Display, Formatter};
+impl Display for LuaError {
+	fn fmt(&self, f: &mut Formatter<'_>) -> std::fmt::Result {
+		write!(f, "LuaError")
+	}
+}
+
 #[lua_function]
 fn add(_state: LuaState) -> Result<i32, LuaError> {
 	Ok(0)

rglua/Cargo.toml

@@ -1,7 +1,7 @@
 [package]
 name = "rglua"
 description = "Toolkit for garrysmod development with the source sdk and luajit api"
-version = "2.0.1"
+version = "2.1.0"
 authors = ["Vurv <[email protected]>"]
 keywords = ["glua", "garrysmod", "lua", "gmod"]
 categories = ["api-bindings", "external-ffi-bindings", "development-tools::ffi", "game-development", "accessibility"]