# from **Modern** to # ***Unbelievably Modern*** # **C++** ## Coral Kashri, Solidus & ## Daisy Hollman, Google ### CoreC++ 2023-06-06

Why would YOU want to be here?

  • Currently working with C++11/14/17 and unaware of newer standard abilities.
  • Learn about the abilities you might be unaware of (yet)
  • Upgrading is easier when performed step by step

Why would you NOT want to be here?

  • You don't care about bugs in your codebase
  • You don't care about long development times
  • You don't want to use the most modern optimizations
  • You believe in complicated solutions, even when easier ones available

What will we talk about?

  • Code written in C++11/14 vs. C++17
  • Code written in C++11/14/17 vs. C++20
  • How to prepare to and eventually migrate forward? (S~C~A~R~Y but E-A-S-Y!)
  • [Bonus] Interesting C++23 features

Extracting Values From Pair / Tuple (C++11 / 14)

Structured Binding (C++17)

If statements (C++11 / 14)


					

                    

                    

					

                    
                        

                    

				


				

					
If & Switch statements with initializer (C++17)

					

					
				


				

				

					
If statements on compile time information (C++11 / 14)

                    

					

					

				


				

					
If constexpr (C++17)

					

				


				

				

					
Unions (C++11 / 14)

                    

					

					


                    
				


				

					
std::variant (C++17)

					

				


				

					
std::variant & std::visit (C++17)

					

				


				

				

					
There is a Return Value! (C++11 / 14)

					

				


				

					
[[nodiscard]] (C++17)

					

				


				

				

					
std::string substr (C++11 / 14)

                    

					

				


				

					
std::string_view (C++17)

					

				


				

				

					

					
Variadic Templates (C++11 / 14)

                        

						

						

					


					

						
Variadic Templates - Solution Issue

						

						

					

				


				

					

						
Fold-Expressions (C++17)

						

						

					

					

						
Fold-Expressions (C++17) - Solution Issue

						

						

						

					

				


                

				

					
C++17 Features - So Far

					
    
						
  • 
							Structure Binding (auto [&a, &b] = ...)
						
    • 
						
  • 
							If with initializer
						
    • 
						
  • 
							If constexpr
						
    • 
						
  • 
							std::variant & std::visit
						
    • 
						
  • 
							[[nodiscard]]
						
    • 
						
  • 
							std::string_view
						
    • 
						
  • 
							fold-expressions
						
    • 
					

				


                

                    
More C++17 Features

                    
    
                        
  • 
                            Guaranteed copy elision
                        
    • 
                        
  • 
                            Class template argument deduction
                        
    • 
                        
  • 
                            Non-type template parameters declared with auto
                        
    • 
                        
  • 
                            Simplified nested namespaces
                        
    • 
						
  • 
							And more!
						
    • 
                    

                


				

				

					
What will we talk about?

					
    
						
  • 
							
								Code written in C++11/14 vs. C++17
							
						
    •  
						
  • 
							
								Code written in C++11/14/17 vs. C++20
							
						
    • 
						
  • 
							
								How to prepare to and eventually migrate forward? (S~C~A~R~Y but E-A-S-Y!)
							
						
    • 
						
  • 
							
								[Bonus] Interesting C++23 features
							
						
    • 
					

				


				

				

					
Sub-Array (C++11 / 14 / 17)

					

					

					

				


				

					
std::span (C++20)

					

					

				


				

				

					
std::size (C++11 / 14 / 17)

					

					

					

				


				

					
std::ssize - signed size (C++20)

					

				


				

				

					

						
Concat Strings (C++11 / 14 / 17)

						

						

					

					

						
External Library: fmt::format

						

					

				


				

					
std::format (C++20)

					

				


				

				

					
nodiscard (C++17)

					

					

					

					

					

				


				

					
nodiscard("description") (C++20)

					

				


				

				

					
Constraints In C++17

					

					

				


				

					
Concepts & Requires (C++20)

					

					
				


				

				

					
Interfaces (C++11 / 14 / 17)

					

					

						

							

						

						

							

						

					

				


				

					
Concepts as Interfaces (C++20)

					

					

						

							

							

							

						

						

							

							

							

						

					

				


				

				

					
C++20 Features - So Far

					
    
						
  • 
							std::span
						
    • 
						
  • 
							std::ssize
						
    • 
						
  • 
							std::format / ranges 3rd party adoption
						
    • 
						
  • 
							[[nodiscard("Description")]]
						
    • 
						
  • 
							Concepts as named constraints
						
    • 
						
  • 
							Concepts as interface
						
    • 
					

				


				

					
More C++20 Features

					
    
						
  • 
							Consteval
						
    • 
						
  • 
							Designated initializers
						
    • 
						
  • 
							[[likely]] & [[unlikely]]
						
    • 
						
  • 
							[[no_unique_address]]
						
    • 
						
  • 
							Modules
						
    • 
						
  • 
							Coroutines
						
    • 
						
  • 
							Three-way comparison operator <=>
						
    • 
						
  • 
							And more!
						
    • 
					

				


				

                

                    
What will we talk about?

                    
    
                        
  • 
							
								Code written in C++11/14 vs. C++17
							
                        
    •  
                        
  • 
							
								Code written in C++11/14/17 vs. C++20
							
                        
    • 
                        
  • 
							
								How to prepare to and eventually migrate forward? (S~C~A~R~Y but E-A-S-Y!)
							
                        
    • 
                        
  • 
							
								[Bonus] Interesting C++23 features
							
                        
    • 
                    

                


                

					
Migrating Forward

					

						
							
						
					

					

                    	
New Compilers - New Optimizations

					

					

                    	
When don't you want to move forward?

						
							
						
					

                


                

                

                    
What will we talk about?

                    
    
                        
  • 
							
								Code written in C++11/14 vs. C++17
							
                        
    •  
                        
  • 
							
								Code written in C++11/14/17 vs. C++20
							
                        
    • 
                        
  • 
							
								How to prepare to and eventually migrate forward? (S~C~A~R~Y but E-A-S-Y!)
							
                        
    • 
                        
  • 
							
								[Bonus] Interesting C++23 features
							
                        
    • 
                    

                


                

                

					
subscript operator -  operator[]

					

						

						

						

					

					

						

					

					

						

					

				


                

                    
operator[] with multiple parameters (C++23)

                    

                


				

					
More C++23 Features

					
    
						
  • 
							std::mdspan
						
    • 
						
  • 
							Deducing this
						
    • 
						
  • 
							flat_map & flat_set
						
    • 
						
  • 
							And more!
						
    • 
					

				


                

                

                    # Questions Time!
                    ## From Modern to Unbelievably Modern C++
                    |                              |   Coral Kashri, Solidus   |       Daisy Hollman, Google      |
                    | :--------------------------: | :-----------------------: | :------------------------------: |
                    | ![](twitter-logo.png#center) |        @koralkashri       |         @The_Whole_Daisy         |
                    |                              |    coralkashri@gmail.com  |            cpp@dsh.fyi           |
                    | ![](linkedin.png#center)     |        Coral Kashri       |       (Not really on LinkedIn)       |