Support paths as well

Fixes #5

src/lib.rs

@@ -129,7 +129,7 @@ struct S {
 */
 #[macro_export]
 macro_rules! big_array {
-    ($name:ident; $($len:tt,)+) => {
+    ($name:ident; $($len:expr,)+) => {
         pub trait $name<'de>: Sized {
             fn serialize<S>(&self, serializer: S) -> $crate::reex::result::Result<S::Ok, S::Error>
                 where S: $crate::reex::Serializer;

tests/const_path.rs

@@ -0,0 +1,28 @@
+#![no_std]
+
+extern crate serde;
+#[macro_use]
+extern crate serde_derive;
+extern crate serde_json;
+#[macro_use]
+extern crate serde_big_array;
+
+mod module {
+    pub const NUMBER: usize = 127;
+}
+
+big_array! { BigArray; module::NUMBER, }
+
+#[derive(Serialize, Deserialize)]
+struct S {
+    #[serde(with = "BigArray")]
+    arr: [u8; module::NUMBER],
+}
+
+#[test]
+fn test() {
+    let s = S { arr: [1; module::NUMBER] };
+    let j = serde_json::to_string(&s).unwrap();
+    let s_back = serde_json::from_str::<S>(&j).unwrap();
+    assert!(&s.arr[..] == &s_back.arr[..]);
+}