diff --git a/src/macros.rs b/src/macros.rs
index 7777d1438c26ff8c770480bee68c179d5490e364..1d50f6571be4b313e50a9805c37d2cf393500373 100644
--- a/src/macros.rs
+++ b/src/macros.rs
@@ -18,4 +18,17 @@ macro_rules! dbg_code {
     ($code:stmt) => {
         #[cfg(debug_assertions)] $code
     }
+}
+
+// Given a function name, return type and variant, will generate the all-so
+// common `union_value.as_variant()` method.
+macro_rules! union_cast_method_impl {
+    ($func_name:ident, $ret_type:ty, $variant:path) => {
+        fn $func_name(&self) -> &$ret_type {
+            match self {
+                $variant(content) => return content,
+                _ => unreachable!(),
+            }
+        }
+    }
 }
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