std::basic_osyncstream::basic_osyncstream(3)

NAME
std::basic_osyncstream::basic_osyncstream - std::basic_osyncstream::basic_osyncstream

Synopsis
   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.

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

Example
// Run this code
 #include <string_view>
 #include <syncstream>
 #include <iostream>
 #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:
 ░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░
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 ████████████████████████████████████████████████████████████████████████████████████████████████████
 Lack of synchronization may cause some interference on output:
 ████▓▓██▒▒▒▒▓▓██░░▒▒██░░▒▒░░░░▒▒░░▓▓▒▒██░░████████████▓▓██████▓▓▒▒▓▓██░░████▓▓▓▓██▒▒░░░░░░░░▓▓░░▓▓██▒▒▒▒▒▒▒▒▓▓██▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒░░▒▒▒▒░░▒▒▒▒▒▒▒▒▒▒▓▓▒▒▒▒▒▒▒▒▒▒▒▒██░░░░░░░░▓▓▓▓▓▓▓▓▓▓▓▓▓▓░░▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓████████▓▓▓▓▓▓▓▓▓▓▓▓░░▓▓▓▓
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See also
   constructor constructs a basic_syncbuf object
                 (public member function of std::basic_syncbuf<CharT,Traits,Allocator>)