===
How to build:
g++ -std=c++20 <filename>
How to run:
./a.out
===
TODO:
- Explain has_member_func.cpp more.
- add zip.
- expand_all, increment all, print all parameter packs. already present in my other github repo named templates.
- to_string variadic.
- add FIBONACCI (not factorial!)
- printing type information with constexpr if
- print_variadic -> printing parameter pack.
- variable templates (NOT to be confused with variadic templates)
- add notes from you drive doc.
use sizeof...(args) to find "parameter pack" size.
Fold expressions is a nice syntax to evaluate binary operators at compile-time. Fold expressions reduce parameter packs on binary operators.
The usage of parameter packs obeys a typical pattern for class templates.
Perform an operation on the first element of the parameter pack and recursively invoke the operation on the remaining elements. The recursion ends after a finite number of steps. The boundary condition is typically a fully specialized template.
Metadata and Metafunctions# At compile-time, we speak about metadata and metafunctions instead of data and functions.
Metadata: Types and integral types that are used in metafunctions. Metafunctions: Functions that are executed at compile-time. Class templates are used to implement metafunctions.
Return their value by ::value. Return their type by ::type.
template< bool B, class T = void > struct enable_if;
If B is true, std::enable_if has a public member typedef type, equal to T; otherwise, there is no member typedef.
This metafunction is a convenient way to leverage SFINAE prior to C++20's concepts, in particular for conditionally removing functions from the candidate set based on type traits, allowing separate function overloads or specializations based on those different type traits.
"Substitution Failure Is Not An Error"
This rule applies during overload resolution of function templates: When substituting the explicitly specified or deduced type for the template parameter fails, the specialization is discarded from the overload set instead of causing a compile error.
This feature is used in template metaprogramming.