1. Modern C++ Pitfalls Mihai Todor 09.04.2015
Disclaimer: This presentation is focused on C++11/14 features and assumes a basic understanding of C++

2. What are we trying to achieve?
Rigurous compile-time checks
Compile once, run many times
We have to be realistic, though
Javascript doesn’t try very hard 
Why does parseInt(1/0, 19) return 18?* *

3. Recap I Some funky template magic Move semantics Auto nullptr
Range-based for loops
override and final
Strongly-typed enums
Lambdas
Explicitly defaulted and deleted functions
Smart pointers
Some funky template magic

4. Recap II Template factory with type detection
Template factory with method detection
There are some issues in these two examples!

5. decltype and std::declval
Standardized version of typeof
Queries the return type of an expression
Doesn’t evaluate its operand
Perfect return type forwarding (C++14)*
std::declval
Obtains the type of an expression in an unevaluated context (inside decltype)
Access to member functions without invoking constructors *

6. Let’s play with references*
std::remove_reference
std::add_lvalue_reference
std::add_rvalue_reference
std::is_reference
std::is_lvalue_reference
std::is_rvalue_reference
*See the <type_traits> header:

7. But why do we need to use std::declval anyway?
class Object {};
template <typename T>
auto ReturnInput(T &input) -> decltype(T()) {
return input; } …
Object obj;
Can ReturnInput take obj as a parameter?

8. But why do we need to use std::declval anyway? – Part II
Object has a private default constructor and the expression inside declval needs to be valid!
This will work:
auto ReturnInput(T &input) -> decltype(std::declval<T>())

9. SFINAE Substitution Failure Is Not An Error
Applies during overload resolution of function templates
Expression SFINAE (C++11)
Removes functions from the list of overloads if the expression inside decltype is not valid* *

10. Why did I show you all of this?
Let’s get back to
TemplateFactoryWithMethodDetection.cpp
A real use case for method detection can be found here:

11. Default Template Arguments for Metod Templates
We can have template methods inside template classes
Before C++11, they could not have default template arguments
More details on StackOverflow* *

12. Range-based for loops
References to certain contaier objects can be problematic

13. <algorithm> Pitfalls
std::lower_bound
std::upper_bound
std::equal_range
std::binary_search
They work on any sorted sequence container, including std::list!
std::advance has O(N) complexity for non-random access*
Detailed information here: *

14. make_shared and make_unique
Create new instances of shared_ptr and unique_ptr
They address multiple issues:
Improved performance
Exception safety

15. See my activity on StackOverflow:
stackoverflow.com/users/ /mihai-todor
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Github: github.com/mihaitodor