Add printgm macro

Now it uses the ``format!`` macro style so you'd call it as so: ``rglua::printgm!(state, "Hello world {}", 24)``

Author: vurvdev

Cargo.toml

@@ -11,4 +11,4 @@ license = "MIT"
 
 [dependencies]
 dlopen = { git = "https://github.com/Vurv78/rust-dlopen", branch = "future", features = ["derive"] }
-once_cell = "1.7.2"
+once_cell = "1.7.2"

src/helpers.rs

@@ -21,4 +21,23 @@ macro_rules! rstring {
             cstr.to_str().expect("Couldn't unwrap CString")
         }
     }
+}
+
+#[allow(unused_macros)]
+#[macro_export]
+/// Like println!, however it prints to the gmod server's console.
+macro_rules! printgm {
+    // First arg is the lua state.
+    // Rest are varargs.
+    // Can be either a variable storing a str literal, or a referenced String / str variable
+    ($state:expr, $($x:expr),*) => {
+        {
+            let stmt = format!( $($x,)* ); // Everything past the state will be as if it were inside a format! call.
+            let lib = *rglua::LUA_SHARED;
+            lib.lua_getglobal($state, rglua::cstring!("print") );
+            lib.lua_pushstring($state, rglua::cstring!(stmt) );
+            // 1 arg, 0 results
+            lib.lua_call($state, 1, 0);
+        }
+    };
 }