From 8d07d8e00a7235223425d529de1ae589ddf28bde Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Luk=C3=A1=C5=A1=20Hozda?= <luk.hozda@gmail.com>
Date: Fri, 9 Feb 2018 22:27:41 +0100
Subject: [PATCH] lock debug messages behind 'debug_msgs' feature

---
 Cargo.toml    | 3 +++
 src/engine.rs | 4 ++--
 src/lib.rs    | 8 ++++++++
 3 files changed, 13 insertions(+), 2 deletions(-)

diff --git a/Cargo.toml b/Cargo.toml
index 1a7eef77..16bdba55 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -12,3 +12,6 @@ include = [
     "scripts/*.rhai",
     "Cargo.toml"
 ]
+
+[features]
+debug_msgs = []
diff --git a/src/engine.rs b/src/engine.rs
index a00fbc2c..4b6438d3 100644
--- a/src/engine.rs
+++ b/src/engine.rs
@@ -160,7 +160,7 @@ impl Engine {
         ident: String,
         args: Vec<&mut Any>,
     ) -> Result<Box<Any>, EvalAltResult> {
-        println!(
+        debug_println!(
             "Trying to call function {:?} with args {:?}",
             ident,
             args.iter().map(|x| (&**x).type_id()).collect::<Vec<_>>()
@@ -196,7 +196,7 @@ impl Engine {
     }
 
     pub fn register_fn_raw(&mut self, ident: String, args: Option<Vec<TypeId>>, f: Box<FnAny>) {
-        println!("Register; {:?} with args {:?}", ident, args,);
+        debug_println!("Register; {:?} with args {:?}", ident, args);
 
         let spec = FnSpec { ident, args };
 
diff --git a/src/lib.rs b/src/lib.rs
index f03ff9d5..14bc19a9 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -34,6 +34,13 @@
 #![allow(warnings, unknown_lints, type_complexity, new_without_default_derive,
          needless_pass_by_value, too_many_arguments)]
 
+// needs to be here, because order matters for macros
+macro_rules! debug_println {
+    () => (#[cfg(feature = "debug_msgs")] {print!("\n")});
+    ($fmt:expr) => (#[cfg(feature = "debug_msgs")] {print!(concat!($fmt, "\n"))});
+    ($fmt:expr, $($arg:tt)*) => (#[cfg(feature = "debug_msgs")] {print!(concat!($fmt, "\n"), $($arg)*)});
+}
+
 mod any;
 mod call;
 mod engine;
@@ -46,3 +53,4 @@ mod tests;
 pub use any::Any;
 pub use engine::{Engine, EvalAltResult, Scope};
 pub use fn_register::RegisterFn;
+