cpp14_inline.hpp File Reference

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Macro Definition Documentation

ARENE_CPP14_INLINE_VARIABLE

#define ARENE_CPP14_INLINE_VARIABLE	(		type,
			name )

Value:

  namespace { /* NOLINT(google-build-namespaces) explicitly want per-TU instantiations*/                   \
  /* NOLINTNEXTLINE(cppcoreguidelines-avoid-non-const-global-variables, bugprone-macro-parentheses) */     \
  ARENE_MAYBE_UNUSED constexpr auto& name = ::arene::base::detail::cpp14_inline_static_const<type>::value; \
  }                                                                                                        \
  ARENE_REQUIRE_SEMICOLON

Emulates C++17's inline variable declarations for function objects.

Parameters

type	The type of the function object to instantiate
name	The name the instantiated object should have in the containing namespace.

This macro is used to correctly declare the instantiation of function objects in a way compatible with both C++14 and >= C++17 contexts, inspired by Eric Niebler's original paper here: https://ericniebler.com/2014/10/21/customization-point-design-in-c11-and-beyond/

In a <= C++17 context, the type is simply declared as inline constexpr type name{} . In C++14 contexts, where inline variable declarations are not permitted, the same effect is achieved by indirecting through the arene::base::detail::cpp14_inline_static_const helper template. The usage looks like so: