C++11: 10 Features You Should be Using. Gordon R&D Runtime Engineer Codeplay Software Ltd.

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C++11: 10 Features You Should be Using Gordon Brown

1 C++11: 10 Features You Should be Using Gordon R&D Runtime Engineer Codeplay Software Ltd.

2 Agenda Default and Deleted Methods Static Assertions Delegated and Inherited Constructors Null Pointer Type Enum Classes Automatic Type Deduction Ranged For Loops Smart Pointers Lambdas and Function Type Move Semantics 2

3 Default and Deleted Functions New 'default' keyword specifies default constructor or operator Useful when partially implementing the rule of three (or five) 3

4 Default and Deleted Functions Example: foo uses the default copy constructor and assignment operator 4

5 Default and Deleted Functions New 'delete' keyword specifies a constructor or operator as unavailable Useful for restricting the way a type can be used 5

6 Default and Deleted Functions Example: foo is non-copyable 6

7 Agenda Default and Deleted Methods Static Assertions Delegated and Inherited Constructors Null Pointer Type Enum Classes Automatic Type Deduction Ranged For Loops Smart Pointers Lambdas and Function Type Move Semantics 7

8 Static Assertions Compile time assertions Useful for generating compiler time errors for templates 8

9 Example: Static Assertions foo<int, 0> f; would give this compiler error 9

10 Agenda Default and Deleted Methods Static Assertions Delegated and Inherited Constructors Null Pointer Type Enum Classes Automatic Type Deduction Ranged For Loops Smart Pointers Lambdas and Function Type Move Semantics 10

11 Delegated and Inherited Constructors Delegated constructors allows one constructor to call another Useful for avoiding code duplication for initialization 11

12 Delegated and Inherited Constructors Example: foo's default constructor calls foo's second constructor foo() foo(int, int, int) 12

13 Delegated and Inherited Constructors Inherited constructors allows a class to inherit constructors from its base class Useful for avoiding constructors that simply pass on the same parameters 13

14 Delegated and Inherited Constructors Example: bar inherits the constructors: bar () bar (int) 14

15 Agenda Default and Deleted Methods Static Assertions Delegated and Inherited Constructors Null Pointer Type Enum Classes Automatic Type Deduction Ranged For Loops Smart Pointers Lambdas and Function Type Move Semantics 15

16 Null Pointer Type New 'nullptr' keyword Alias for the 'nullptr_t' type Comparable to any pointer Not implicitly convertible or comparable to integral types, except bool 16

17 Example: Null Pointer Type Which constructor is called when passing NULL? Which constructor is called when passing nullptr? 17

18 Agenda Default and Deleted Methods Static Assertions Delegated and Inherited Constructors Null Pointer Type Enum Classes Automatic Type Deduction Ranged For Loops Smart Pointers Lambdas and Function Type Move Semantics 18

19 Enum Classes Improvement on traditional enums Allows forward declarations Does not pollute top level namespace Not implicitly convertible to integers Can specify the element size 19

20 Enum Classes Example: Each element of the enum is an integer. animal_type animaltype = animal_type::dog 20

21 Agenda Default and Deleted Methods Static Assertions Delegated and Inherited Constructors Null Pointer Type Enum Classes Automatic Type Deduction Ranged For Loops Smart Pointers Lambdas and Function Type Move Semantics 21

22 Automatic Type Deduction New 'auto' keyword allows compile type deduction Useful when a type is very complex such as iterators or functions 22

23 Example: Automatic Type Deduction 23

24 Agenda Default and Deleted Methods Static Assertions Delegated and Inherited Constructors Null Pointer Type Enum Classes Automatic Type Deduction Ranged For Loops Smart Pointers Lambdas and Function Type Move Semantics 24

25 Ranged For Loops Simpler syntax for iterable types Can be used on any type that has either: begin() and end() methods begin(std::vector) and end(std::vector) functions 25

26 Example: Ranged For Loops It is also possible to use auto as the type for i 26

27 Agenda Default and Deleted Methods Static Assertions Delegated and Inherited Constructors Null Pointer Type Enum Classes Automatic Type Deduction Ranged For Loops Smart Pointers Lambdas and Function Type Move Semantics 27

28 Smart Pointers Standard library template pointer classes Aims to solve the problems associated with raw pointers management shared_ptr reference counts the pointer unique_ptr only allows a single copy of the pointer 28

29 Smart Pointers Example: Oops, the destructor isn't deleting the raw pointer! 29

30 Smart Pointers Example: The shared_ptr handles deleting the pointer automatically 30

31 Agenda Default and Deleted Methods Static Assertions Delegated and Inherited Constructors Null Pointer Type Enum Classes Automatic Type Deduction Ranged For Loops Smart Pointers Lambdas and Function Type Move Semantics 31

32 Lambdas and Function Type Anonymous functions! [] - variable capture ([&], [=], [this]) () - parameters {} - function body Function type 'std::function<void(int)>' 32

33 Lambdas and Function Type Example: 33

34 Agenda Default and Deleted Methods Static Assertions Delegated and Inherited Constructors Null Pointer Type Enum Classes Automatic Type Deduction Ranged For Loops Smart Pointers Lambdas and Function Type Move Semantics 34

35 Move Semantics L-value An expression with identity, that has address-able memory Variables, pointers, references, parameters R-value An expression with no identity, that does not have address-able memory Literals, temporaries 35

36 Move Semantics Example: These are all l-values 36

37 Move Semantics Example: These are all r-values 37

38 Move Semantics L-value reference int &r; R-value reference int &&r; std::move() Prolongs an r-value reference 38

39 Example: Move Semantics When make_foo returns, a temporary foo object is created on the stack which is used to construct f 39

40 Example: Move Semantics By using std::move() the move constructor for foo is triggered therefore avoiding the copy Important to note that when using move semantics, the previous object becomes invalid 40

41 What Next? C++11 is awesome Try it out There are many other features C++14 is now out Try that out too 41

C++11 and Compiler Update

C++11 and Compiler Update John JT Thomas Sr. Director Application Developer Products About this Session A Brief History Features of C++11 you should be using now Questions 2 Bjarne Stroustrup C with Objects