std::owner_less

 

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Smart pointers unique_ptr (C++11) shared_ptr (C++11) weak_ptr (C++11) auto_ptr (until C++17*) owner_less (C++11) owner_less<void> (C++17) owner_hash (C++26) owner_equal (C++26) enable_shared_from_this (C++11) bad_weak_ptr (C++11) default_delete (C++11) out_ptr_t (C++23) inout_ptr_t (C++23) Low level memory management operator new operator new[] operator delete operator delete[] get_new_handler (C++11) set_new_handler launder (C++17) bad_alloc bad_array_new_length (C++11) nothrow_t align_val_t (C++17) destroying_delete_t (C++20) new_handler nothrow Miscellaneous pointer_traits (C++11) to_address (C++20) addressof (C++11) align (C++11) assume_aligned (C++20) C Library malloc calloc realloc    aligned_alloc (C++17) free

 

Defined in header <memory>
template<> struct owner_less<void>;		(since C++17)

std::owner_less<> is a specialization of std::owner_less with parameter types deduced.

Member types

Member type	Definition
is_transparent	/* unspecified */

Notes

The member type is_transparent indicates to the caller that this function object is a transparent function object: it accepts arguments of arbitrary types and uses perfect forwarding, which avoids unnecessary copying and conversion when the function object is used in heterogeneous context, or with rvalue arguments. In particular, template functions such as std::set::find and std::set::lower_bound make use of this member type on their Compare types.

Member functions

operator()

compares its arguments using owner-based semantics (function)

std::owner_less<void>::operator()

template<class T, class U> bool operator()( const std::shared_ptr<T>& lhs,                  const std::shared_ptr<U>& rhs ) const;		(since C++17)
template<class T, class U> bool operator()( const std::shared_ptr<T>& lhs,                  const std::weak_ptr<U>& rhs ) const;		(since C++17)
template<class T, class U> bool operator()( const std::weak_ptr<T>& lhs,                  const std::shared_ptr<U>& rhs ) const;		(since C++17)
template<class T, class U> bool operator()( const std::weak_ptr<T>& lhs,                  const std::weak_ptr<U>& rhs ) const;		(since C++17)

Compares lhs and rhs using owner-based semantics. Effectively calls lhs.owner_before(rhs).

The ordering is strict weak ordering relation.

lhs and rhs are equivalent only if they are both empty or share ownership.

Parameters

lhs, rhs

-

shared-ownership pointers to compare

Return value

true if lhs is less than rhs as determined by the owner-based ordering.

Exceptions

noexcept specification:  

noexcept

  

See also

owner_before	provides owner-based ordering of shared pointers (public member function of std::shared_ptr<T>)
owner_before	provides owner-based ordering of weak pointers (public member function of std::weak_ptr<T>)