How Does `auto` in C 17 Template Parameters Simplify Template Usage?

Benefits of Auto in C 17 Template Parameters

Template feature introduced in C 17 offers several advantages for parameterizing templates.

Type Deduction:

auto in template parameters enables automatic type deduction. Instead of specifying the type explicitly, you can simply use auto, which infers the type from the value provided during instantiation. This simplifies the syntax and eliminates potential type errors.

Conciseness:

Using auto eliminates the need to specify the type explicitly. This leads to shorter and more readable template declarations and instantiations. For example:

// Pre-C++17
template <typename Type, Type value>
constexpr Type constant = value;

// C++17
template <auto value>
constexpr auto constant = value;

Compile-Time List Simplification:

auto facilitates the creation of compile-time lists of heterogeneous or homogeneous values. For instance:

// Heterogeneous value list
template <auto ... vs>
struct HeterogenousValueList {};

// Homogenous value list
template <auto v0, decltype(v0) ... vs>
struct HomogenousValueList {};

This simplifies code that previously required wrapping values in additional templates or using complex syntax.

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