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void qSwap(T &lhs, T &rhs)

Function Documentation

[constexpr noexcept(...)] template <typename T> void qSwap(T &lhs, T &rhs)

Exchanges the values of variables lhs and rhs, taking type-specific swap() overloads into account.

This function is Qt's version of boost::swap(), and is equivalent to

using std::swap;   // bring std::swap into scope (for built-in types)
swap(lhs, rhs);    // unqualified call (picks up type-specific overloads
                   // via Argument-Dependent Lookup, or falls back to std::swap)

Use this function primarily in generic code, where you would traditionally have written the above two lines, because you don't know anything about T.

If you already know what T is, then use one of the following options, in order of preference:

  • lhs.swap(rhs); if such a member-swap exists
  • std::swap(lhs, rhs); if no type-specific swap() exists

See boost::swap() on boost.org for more details.

See also std::swap on cppreference.com, Swappable on cppreference.com.

Note: This function does not throw any exception when "std::is_nothrow_swappable_v<T>" is true.

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