How to determine programmatically if an expression is rvalue or lvalue in C++?

by

Most of the work is already done for you by the stdlib, you just need a function wrapper:

template <typename T>
constexpr bool is_lvalue(T&&) {
  return std::is_lvalue_reference<T>{};
}

in the case you pass a std::string lvalue then T will deduce to std::string& or const std::string&, for rvalues it will deduce to std::string

Note that Yakk’s answer will return a different type, which allows for more flexibility and you should read that answer and probably use it instead.

More Related Contents:

  1. Rvalue Reference is Treated as an Lvalue?
  2. On how to recognize Rvalue or Lvalue reference and if-it-has-a-name rule
  3. Is it valid to bind non-const lvalue-references to rvalues in C++ 11?(modified)
  4. One VS2010 bug ? Allowing binding non-const reference to rvalue WITHOUT EVEN a warning?
  5. non-class rvalues always have cv-unqualified types
  6. In C++, what categories (lvalue, rvalue, xvalue, etc.) can expressions that produce temporaries of class type fall into?
  7. Do rvalue references allow dangling references?
  8. Passing rvalues through std::bind
  9. What is the value category of the operands of C++ operators when unspecified?
  10. Isn’t the const modifier here unnecessary? [duplicate]
  11. Why is taking the address of a temporary illegal?
  12. Why does std::forward have two overloads?
  13. should std::common_type use std::decay?
  14. Futures vs. Promises
  15. Why does unique_ptr take two template parameters when shared_ptr only takes one?
  16. reinterpret_cast between char* and std::uint8_t* – safe?
  17. Why Aren’t `std::uniform_int_distribution` and `std::uniform_int_distribution` Allowed?
  18. Why can’t I use with g++ 4.9.2?
  19. C++11 Change `auto` Lambda to a different Lambda?
  20. how to specify vc11 lambda calling convention
  21. Partial specialization of function templates
  22. Does std::bind work with move-only types in general, and std::unique_ptr in particular?
  23. Dynamic dispatching of template functions?
  24. C++11 cross compiler/standard library random distribution reproducibility
  25. Is it possible to invoke a user-defined conversion function via list-initialization?
  26. Is there a proper ‘ownership-in-a-package’ for ‘handles’ available?
  27. Is there a reference_wrapper for rvalue references?
  28. Why does an lvalue cast work?
  29. using declaration in variadic template
  30. get part of std::tuple

Leave a Comment