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| Member functions | ||||
| Non-member functions | ||||
out_ptr |
Defined in header <memory> | ||
template<class Pointer=void,class Smart,class...Args> auto out_ptr( Smart& s, Args&&...args); | (since C++23) | |
Returns anstd::out_ptr_t with deduced template arguments that captures arguments for resetting by reference.
The program is ill-formed if construction of the return value (see below) is ill-formed.
Contents |
| s | - | the object (typically a smart pointer) to adapt |
| args... | - | the arguments for resetting to capture |
std::out_ptr_t<Smart, P, Args&&>(s,std::forward<Args>(args)...), whereP is
Pointer, ifPointer is not avoid type. Otherwise,Users may specify the template argument for the template parameterPointer, in order to interoperate with foreign functions that take aPointer*.
As all arguments for resetting are captured by reference, the returnedout_ptr_t should be a temporary object destroyed at the end of the full-expression containing the call to the foreign function, in order to avoid dangling references.
| Feature-test macro | Value | Std | Feature |
|---|---|---|---|
__cpp_lib_out_ptr | 202106L | (C++23) | std::out_ptr,std::inout_ptr |
202311L | (C++26) | freestandingstd::out_ptr andstd::inout_ptr |
Usestd::out_ptr to adapt a smart pointer forsqlite3_open, which expects asqlite3** as an out parameter.
#include <memory>#include <sqlite3.h> int main(){auto close_db=[](sqlite3* db){ sqlite3_close(db);}; {// open an in-memory database, and manage its lifetime with std::unique_ptrstd::unique_ptr<sqlite3, decltype(close_db)> up; sqlite3_open(":memory:", std::out_ptr(up)); sqlite3* db= up.get();// do something with db ...}{// same as above, but use a std::shared_ptrstd::shared_ptr<sqlite3> sp; sqlite3_open(":memory:", std::out_ptr(sp, close_db)); sqlite3* db= sp.get();// do something with db ...}}
(C++23) | creates aninout_ptr_t with an associated smart pointer and resetting arguments(function template)[edit] |
(C++14)(C++20) | creates a unique pointer that manages a new object (function template)[edit] |
| creates a shared pointer that manages a new object (function template)[edit] |
