Template Metaprogramming: Practical Application - Jody Hagins - CppCon 2021

Discover the practical application of template metaprogramming in C++ with Jody Hagins, exploring concepts like `void T`, `requires`, and `full-expression`, and uncovering performance optimizations and new features in C++20.

Key takeaways

Use of void T vs requires for type checking
void T is preferred over requires for performance
void T is a way to normalize types and can help with type checking
There is a performance difference between using void T and not using it
The performance difference is significant and noticeable
To measure performance, use the --time-trace flag in Clang
full-expression is a concept that is useful in metaprogramming
constexpr is used to create compile-time values
STATIC_ASSERT is used to check if a value is true at compile-time
index_sequence is a type that can be used to iterate over a list of types
void T can be used to create a recursive alias template
orderable is a concept that is used to check if a type is orderable
std::tuple can be used to create a tuple of types
std::pair can be used to create a pair of types
SFINAE is a technique used to enable or disable function overloads based on the type of arguments
std::sort can be used to sort a list of types
ENABLE_IF is a template function that can be used to enable or disable a function based on the type of arguments
typeid can be used to get the type of an object at runtime
type_identity is a template that can be used to create a type identity
template metaprogramming is a technique used to create code that manipulates types at compile-time
C++20 introduces new features that make it easier to use void T
Clang has a feature called --time-trace that can be used to measure the time it takes to compile code

Template Metaprogramming: Practical Application - Jody Hagins - CppCon 2021

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