[syncstream.syncbuf.cons]

# 31 Input/output library [[input.output]](./#input.output)

## 31.11 Synchronized output streams [[syncstream]](syncstream#syncbuf.cons)

### 31.11.2 Class template basic_syncbuf [[syncstream.syncbuf]](syncstream.syncbuf#cons)

#### 31.11.2.2 Construction and destruction [syncstream.syncbuf.cons]

[ð](#lib:basic_syncbuf,constructor)

`basic_syncbuf(streambuf_type* obuf, const Allocator& allocator);
`

[1](#1)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iostreams.tex#L12669)

*Effects*: Sets *wrapped* to obuf[.](#1.sentence-1)

[2](#2)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iostreams.tex#L12673)

*Postconditions*: get_wrapped() == obuf andget_allocator() == allocator are true[.](#2.sentence-1)

[3](#3)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iostreams.tex#L12678)

*Throws*: Nothing unless an exception is thrown
by the construction of a mutex or
by memory allocation[.](#3.sentence-1)

[4](#4)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iostreams.tex#L12684)

*Remarks*: A copy of allocator is used
to allocate memory for internal buffers
holding the associated output[.](#4.sentence-1)

[ð](#lib:basic_syncbuf,constructor_)

`basic_syncbuf(basic_syncbuf&& other);
`

[5](#5)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iostreams.tex#L12697)

*Postconditions*: The value returned by this->get_wrapped() is the value returned by other.get_wrapped() prior to calling this constructor[.](#5.sentence-1)

Output stored in other prior to calling this constructor
will be stored in *this afterwards[.](#5.sentence-2)

other.pbase() == other.pptr() andother.get_wrapped() == nullptr are true[.](#5.sentence-3)

[6](#6)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iostreams.tex#L12710)

*Remarks*: This constructor disassociates other from its wrapped stream buffer,
ensuring destruction of other produces no output[.](#6.sentence-1)

[ð](#lib:basic_syncbuf,destructor)

`~basic_syncbuf();
`

[7](#7)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iostreams.tex#L12723)

*Effects*: Calls emit()[.](#7.sentence-1)

[8](#8)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iostreams.tex#L12727)

*Throws*: Nothing[.](#8.sentence-1)

If an exception is thrown from emit(),
the destructor catches and ignores that exception[.](#8.sentence-2)
