Add a helper method to set eviction function after construction

Signed-off-by: Davanum Srinivas <[email protected]>

lru/lru.go

@@ -44,6 +44,11 @@ func NewWithEvictionFunc(size int, f EvictionFunc) *Cache {
 	return c
 }
 
+// SetEvictionFunc updates the eviction func
+func (c *Cache) SetEvictionFunc(f EvictionFunc) {
+	c.cache.OnEvicted = f
+}
+
 // Add adds a value to the cache.
 func (c *Cache) Add(key Key, value interface{}) {
 	c.lock.Lock()