From 848f8b6c3a496c3b45a32b0f83cc4913e65c66a0 Mon Sep 17 00:00:00 2001
From: Patrick Mylund Nielsen <patrick@patrickmylund.com>
Date: Mon, 2 Jan 2012 11:32:05 +0100
Subject: [PATCH] Clarification about storing pointers; renamed Purge to Flush
 (like Memcache)

---
 cache.go      | 25 +++++++++++++++++++++++--
 cache_test.go | 24 ++++++++++++++++++++++++
 2 files changed, 47 insertions(+), 2 deletions(-)

diff --git a/cache.go b/cache.go
index b93eba6..3eeedce 100644
--- a/cache.go
+++ b/cache.go
@@ -59,7 +59,28 @@ import (
 //             foo := x.(*MyStruct)
 //             ...
 //     }
-
+//
+// If you store a reference type like a pointer, slice, map or channel, you do not need to
+// run Set if you modify the underlying data. The cache does not serialize its data, so if
+// you modify a struct whose pointer you've stored in the cache, retrieving that pointer
+// with Get will point you to the same data:
+//
+//     foo := &MyStruct{Num: 1}
+//     c.Set("foo", foo, 0)
+//     ...
+//     x, _ := c.Get("foo")
+//     foo := x.(MyStruct)
+//     fmt.Println(foo.Num)
+//     ...
+//     foo.Num++
+//     ...
+//     x, _ := c.Get("foo")
+//     foo := x.(MyStruct)
+//     foo.Println(foo.Num)
+//
+// will print:
+//     1
+//     2
 
 type Cache struct {
 	*cache
@@ -146,7 +167,7 @@ func (c *cache) DeleteExpired() {
 }
 
 // Deletes all items in the cache
-func (c *cache) Purge() {
+func (c *cache) Flush() {
 	c.mu.Lock()
 	defer c.mu.Unlock()
 
diff --git a/cache_test.go b/cache_test.go
index 28b8ee1..a750ac0 100644
--- a/cache_test.go
+++ b/cache_test.go
@@ -95,3 +95,27 @@ func TestCacheTimes(t *testing.T) {
 		t.Error("Found d when it should have been automatically deleted (later than the default)")
 	}
 }
+
+type TestStruct struct {
+	Num int
+}
+
+func TestStorePointerToStruct(t *testing.T) {
+	tc := New(0, 0)
+	tc.Set("foo", &TestStruct{Num: 1}, 0)
+	x, found := tc.Get("foo")
+	if !found {
+		t.Fatal("*TestStruct was not found for foo")
+	}
+	foo := x.(*TestStruct)
+	foo.Num++
+
+	y, found := tc.Get("foo")
+	if !found {
+		t.Fatal("*TestStruct was not found for foo (second time)")
+	}
+	bar := y.(*TestStruct)
+	if bar.Num != 2 {
+		t.Fatal("TestStruct.Num is not 2")
+	}
+}