cpp.md

@@ -841,6 +841,20 @@ UNIx STanDard Header file
 * [C言語 未初期化変数の罠 \- 気まま研究所ブログ]( https://aonasuzutsuki.hatenablog.jp/entry/2018/12/21/111450 )
 * [変数の初期化をサボるな，それから \-Wshadow オプションを使え \- akihiko’s tech note]( https://aki-yam.hatenablog.com/entry/20130718/1374163303 )
 
+### 複雑な処理をした結果のconst初期化
+[C++ Core Guidelines]( https://isocpp.github.io/CppCoreGuidelines/CppCoreGuidelines#es28-use-lambdas-for-complex-initialization-especially-of-const-variables )
+
+e.g.
+``` cpp
+const widget x = [&] {
+    widget val;                                // assume that widget has a default constructor
+    for (auto i = 2; i <= N; ++i) {            // this could be some
+        val += some_obj.do_something_with(i);  // arbitrarily long code
+    }                                          // needed to initialize x
+    return val;
+}();
+```
+
 ### 配列の初期化
 ``` cpp
 #include <array>