From 3e4736712af36f6c3e272ec1aaee6d5b4ddb33d0 Mon Sep 17 00:00:00 2001
From: Jason Turner <jason@emptycrate.com>
Date: Tue, 2 Jun 2015 08:13:09 -0600
Subject: [PATCH] Additional notes about shared and unique_ptr

---
 07-Considering_Performance.md | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/07-Considering_Performance.md b/07-Considering_Performance.md
index d2eb343..7dcf212 100644
--- a/07-Considering_Performance.md
+++ b/07-Considering_Performance.md
@@ -207,12 +207,20 @@ std::make_shared<ModelObject_Impl>(); // (it's also more readable and concise)
 
 ### Prefer `unique_ptr` to `shared_ptr`
 
-If possible use `unique_ptr` instead of `shared_ptr`. The `unique_ptr` does not need to keep track of its copies because it is not copyable. Because of this it is more efficient than the `shared_ptr`. Equivalent to `shared_ptr` and `make_shared` you should use `make_unique` to create the `unique_ptr`:
+If possible use `unique_ptr` instead of `shared_ptr`. The `unique_ptr` does not need to keep track of its copies because it is not copyable. Because of this it is more efficient than the `shared_ptr`. Equivalent to `shared_ptr` and `make_shared` you should use `make_unique` (C++14 or greater) to create the `unique_ptr`:
 
 ```cpp
 std::make_unique<ModelObject_Impl>();
 ```
 
+Current best practices suggest returning a `unique_ptr` from factory functions as well, then converting the  `unique_ptr` to a `shared_ptr` if necessary.
+
+```cpp
+std::unique_ptr<ModelObject_Impl> factory();
+
+auto shared = std::shared_ptr<ModelObject_Impl>(factory());
+```
+
 ### Get rid of std::endl
 
 `std::endl` implies a flush operation. It's equivalent to `"\n" << std::flush`.