Changes between Version 3 and Version 4 of AnalyzingBuildPerformance

Timestamp:

Oct 12, 2021 10:00:30 AM (3 years ago)

Author:

jer.noble@apple.com

Comment:

Add section on inlined virtual functions.

AnalyzingBuildPerformance

@@ -171 +171 @@
 inline YourClass& MyClass::getFoo() { return YourClass::foo(); }
 }}}
+
+==== Avoid Virtual Inlines ====
+
+Virtual functions will almost never gain any benefit from being inlined (unless callers cast the function itself, e.g.: `foo->Derived::bar()` instead of `foo->bar()`, which is a very uncommon practice). If a virtual function definition in a header file requires including an external header, consider moving the definition into the implementation file. E.g.:
+
+Bad:
+{{{
+#!c++
+// MyClass.h
+#include "YourClass.h"
+class MyClass final : public BaseClass {
+public:
+    void doFoo() final { m_yourClass->doFoo(); }
+
+private:
+    Ref<YourClass> m_yourClass;
+};
+}}}
+
+Good:
+{{{
+#!c++
+// MyClass.h
+class MyClass final : public BaseClass {
+public:
+    void doFoo() final;
+
+private:
+    Ref<YourClass> m_yourClass;
+};
+
+// MyClass.cpp
+#include "MyClass.h"
+#include "YourClass.h"
+void MyClass::doFoo() { m_yourClass->doFoo(); }
+}}}