rule_of_five

Author: cirosantilli

README.adoc

@@ -2509,6 +2509,9 @@ Note that secondary cores in gem5 are kind of broken however: <<gem5-gdb-step-de
 Bibliography:
 
 * https://stackoverflow.com/questions/10490756/how-to-use-sched-getaffinity-and-sched-setaffinity-in-linux-from-c/50117787#50117787
+** https://stackoverflow.com/questions/663958/how-to-control-which-core-a-process-runs-on/50210009#50210009
+** https://stackoverflow.com/questions/280909/cpu-affinity/54478296#54478296
+** https://unix.stackexchange.com/questions/73/how-can-i-set-the-processor-affinity-of-a-process-on-linux/441098#441098 (summary only)
 * https://stackoverflow.com/questions/42800801/how-to-use-gdb-to-debug-qemu-with-smp-symmetric-multiple-processors
 
 === Linux kernel GDB scripts
@@ -20225,14 +20228,6 @@ Programs under link:userland/cpp/[] are examples of https://en.wikipedia.org/wik
 
 * link:userland/cpp/empty.cpp[]
 * link:userland/cpp/hello.cpp[]
-* classes
-** constructor
-*** link:userland/cpp/initializer_list_constructor.cpp[]: documents stuff like `std::vector<int> v{0, 1};` and `std::initializer_list`
-*** link:userland/cpp/most_vexing_parse.cpp[]: the most vexing parse is a famous constructor vs function declaration syntax gotcha!
-**** https://en.wikipedia.org/wiki/Most_vexing_parse
-**** http://stackoverflow.com/questions/180172/default-constructor-with-empty-brackets
-** `virtual` and polymorphism
-*** link:userland/cpp/virtual.cpp[]
 * iostream
 ** link:userland/cpp/copyfmt.cpp[]: `std::copyfmt` restores stream state, see also: https://stackoverflow.com/questions/12560291/set-back-default-floating-point-print-precision-in-c/53673686#53673686
 * fstream
@@ -20247,6 +20242,61 @@ Programs under link:userland/cpp/[] are examples of https://en.wikipedia.org/wik
 *** link:userland/cpp/multimap.cpp[]: `std::multimap`
 ** <<algorithms>> contains a benchmark comparison of different c++ containers
 
+[[cpp-classes]]
+==== C++ classes
+
+[[cpp-constructor]]
+===== C++ constructor
+
+* link:userland/cpp/initializer_list_constructor.cpp[]: documents stuff like `std::vector<int> v{0, 1};` and `std::initializer_list`
+* link:userland/cpp/most_vexing_parse.cpp[]: the most vexing parse is a famous constructor vs function declaration syntax gotcha!
+** https://en.wikipedia.org/wiki/Most_vexing_parse
+** http://stackoverflow.com/questions/180172/default-constructor-with-empty-brackets
+* `virtual` and polymorphism
+** link:userland/cpp/virtual.cpp[]
+
+[[cpp-rule-of-five]]
+====== C++ rule of five
+
+link:userland/cpp/rule_of_five.cpp[]
+
+Output Ubuntu 20.04 GCC 9.3:
+
+....
+constructor?
+constructor
+
+copy?
+constructor
+copy
+
+copy assignment?
+constructor
+copy assignment
+constructor
+copy
+move assignment
+destructor
+
+move?
+constructor
+
+move?
+constructor
+constructor
+move assignment
+destructor
+
+a bunch of destructors?
+destructor
+destructor
+destructor
+destructor
+destructor
+....
+
+https://en.cppreference.com/w/cpp/language/rule_of_three
+
 [[cpp-standards]]
 ==== C++ standards
 

userland/cpp/rule_of_five.cpp

@@ -0,0 +1,75 @@
+// https://cirosantilli.com/linux-kernel-module-cheat#cpp-rule-of-five
+// Adapted from https://en.cppreference.com/w/cpp/language/rule_of_five
+
+#include <cstdlib>
+#include <cstring>
+#include <iostream>
+#include <utility>
+
+class rule_of_five
+{
+    char* cstring;
+ public:
+    rule_of_five(const char* s = "")
+    : cstring(nullptr) {
+        std::cout << "constructor" << std::endl;
+        if (s) {
+            std::size_t n = std::strlen(s) + 1;
+            cstring = new char[n];
+            std::memcpy(cstring, s, n);
+        }
+    }
+
+    ~rule_of_five() {
+        std::cout << "destructor" << std::endl;
+        delete[] cstring;
+    }
+
+    rule_of_five(const rule_of_five& other)
+    : rule_of_five(other.cstring) {
+        std::cout << "copy" << std::endl;
+    }
+
+    rule_of_five& operator=(const rule_of_five& other) {
+        std::cout << "copy assignment" << std::endl;
+        return *this = rule_of_five(other);
+    }
+
+    rule_of_five(rule_of_five&& other) noexcept
+    : cstring(std::exchange(other.cstring, nullptr)) {
+        std::cout << "move" << std::endl;
+    }
+
+    rule_of_five& operator=(rule_of_five&& other) noexcept {
+        std::cout << "move assignment" << std::endl;
+        std::swap(cstring, other.cstring);
+        return *this;
+    }
+};
+
+int main()
+{
+    std::cout << "constructor?" << std::endl;
+    rule_of_five o1{"aaa"};
+    std::cout << std::endl;
+
+    std::cout << "copy?" << std::endl;
+    auto o2{o1};
+    std::cout << std::endl;
+
+    std::cout << "copy assignment?" << std::endl;
+    rule_of_five o3("bbb");
+    o3 = o2;
+    std::cout << std::endl;
+
+    std::cout << "move?" << std::endl;
+    rule_of_five o4(rule_of_five("ccc"));
+    std::cout << std::endl;
+
+    std::cout << "move?" << std::endl;
+    rule_of_five o5("ddd");
+    o5 = rule_of_five("eee");
+    std::cout << std::endl;
+
+    std::cout << "a bunch of destructors?" << std::endl;
+}