std::basic_osyncstream<CharT,Traits,Allocator>::basic_osyncstream
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< cpp | io | basic osyncstream
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Synchronized Output
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std::basic_osyncstream
Public member functions
basic_osyncstream::basic_osyncstream
(C++20)
(C++20)
(C++20)
(C++20)
(C++20)
basic_osyncstream( streambuf_type* buf, const Allocator& a );
(1)
explicit basic_osyncstream( streambuf_type* buf );
(2)
basic_osyncstream( std::basic_ostream <CharT, Traits>& os, const Allocator& a );
(3)
explicit basic_osyncstream( std::basic_ostream <CharT, Traits>& os );
(4)
basic_osyncstream( std::basic_osyncstream && other ) noexcept;
(5)
Constructs new synchronized output stream.
1-4) Constructs the private member std::basic_syncbuf using the buffer and the allocator provided, and initializes the base class with a pointer to the member std::basic_streambuf .
5) Move constructor. Move-constructs the std::basic_ostream base and the std::basic_syncbuf member from the corresponding subobjects of other, then calls set_rdbuf with the pointer to the newly-constructed underlying std::basic_syncbuf to complete the initialization of the base. After this move constructor, other.get_wrapped() returns nullptr and destruction of other produces no output.
[edit] Parameters
buf
-
pointer to the std::basic_streambuf that will be wrapped
os
-
reference to a std::basic_ostream , whose rdbuf() will be wrapped
a
-
the allocator to pass to the constructor of the member std::basic_syncbuf
other
-
another osyncstream to move from
[edit] Example
Run this code
#include <iostream> #include <string_view> #include <syncstream> #include <thread> void worker(const int id, std::ostream &os) { std::string_view block; switch (id) { default: [[fallthrough]]; case 0: block = "██"; break; case 1: block = "▓▓"; break; case 2: block = "▒▒"; break; case 3: block = "░░"; break; } for (int i = 1; i <= 50; ++i) os << block << std::flush ; os << std::endl ; } int main() { std::cout << "Synchronized output should not cause any interference:" << std::endl ; { auto scout1 = std::osyncstream {std::cout }; auto scout2 = std::osyncstream {std::cout }; auto scout3 = std::osyncstream {std::cout }; auto scout4 = std::osyncstream {std::cout }; auto w1 = std::jthread {worker, 0, std::ref (scout1)}; auto w2 = std::jthread {worker, 1, std::ref (scout2)}; auto w3 = std::jthread {worker, 2, std::ref (scout3)}; auto w4 = std::jthread {worker, 3, std::ref (scout4)}; } std::cout << "\nLack of synchronization may cause some interference on output:" << std::endl ; { auto w1 = std::jthread {worker, 0, std::ref (std::cout )}; auto w2 = std::jthread {worker, 1, std::ref (std::cout )}; auto w3 = std::jthread {worker, 2, std::ref (std::cout )}; auto w4 = std::jthread {worker, 3, std::ref (std::cout )}; } }
Possible output:
Synchronized output should not cause any interference: ░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░ ▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒ ▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓ ████████████████████████████████████████████████████████████████████████████████████████████████████ Lack of synchronization may cause some interference on output: ████▓▓██▒▒▒▒▓▓██░░▒▒██░░▒▒░░░░▒▒░░▓▓▒▒██░░████████████▓▓██████▓▓▒▒▓▓██░░████▓▓▓▓██▒▒░░░░░░░░▓▓░░▓▓██▒▒▒▒▒▒▒▒▓▓██▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒░░▒▒▒▒░░▒▒▒▒▒▒▒▒▒▒▓▓▒▒▒▒▒▒▒▒▒▒▒▒██░░░░░░░░▓▓▓▓▓▓▓▓▓▓▓▓▓▓░░▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓████████▓▓▓▓▓▓▓▓▓▓▓▓░░▓▓▓▓ ▒▒▒▒██░░██████████████████████████░░░░░░░░░░░░░░██░░▒▒░░░░░░██████████████████ ▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒░░▒▒░░░░░░░░░░░░░░░░░░░░░░░░░░░░▒▒▒▒▒▒ ░░░░░░
[edit] See also
constructs a
(public member function of
basic_syncbuf object (public member function of
std::basic_syncbuf<CharT,Traits,Allocator>) [edit]