1[/
2 / Copyright (c) 2003-2015 Christopher M. Kohlhoff (chris at kohlhoff dot com)
3 /
4 / Distributed under the Boost Software License, Version 1.0. (See accompanying
5 / file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
6 /]
7
8[section:Handler Handlers]
9
10A handler must meet the requirements of `CopyConstructible` types (C++ Std,
1120.1.3).
12
13In the table below, `X` denotes a handler class, `h` denotes a value of `X`,
14`p` denotes a pointer to a block of allocated memory of type `void*`, `s`
15denotes the size for a block of allocated memory, and `f` denotes a function
16object taking no arguments.
17
18[table Handler requirements
19  [[expression] [return type] [assertion/note\npre/post-conditions]]
20  [
21    [``
22      using boost::asio::asio_handler_allocate;
23      asio_handler_allocate(s, &h);
24    ``]
25    [`void*`]
26    [
27      Returns a pointer to a block of memory of size `s`. The pointer must
28      satisfy the same alignment requirements as a pointer returned by
29      `::operator new()`. Throws `bad_alloc` on failure.\n\n The
30      `asio_handler_allocate()` function is located using argument-dependent
31      lookup. The function `boost::asio::asio_handler_allocate()` serves as a
32      default if no user-supplied function is available.
33    ]
34  ]
35  [
36    [``
37      using boost::asio::asio_handler_deallocate;
38      asio_handler_deallocate(p, s, &h);
39    ``]
40    []
41    [
42      Frees a block of memory associated with a pointer `p`, of at least size
43      `s`, that was previously allocated using `asio_handler_allocate()`.\n\n The
44      `asio_handler_deallocate()` function is located using argument-dependent
45      lookup. The function `boost::asio::asio_handler_deallocate()` serves as a
46      default if no user-supplied function is available.
47    ]
48  ]
49  [
50    [``
51      using boost::asio::asio_handler_invoke;
52      asio_handler_invoke(f, &h);
53    ``]
54    []
55    [
56      Causes the function object `f` to be executed as if by calling `f()`.\n\n
57      The `asio_handler_invoke()` function is located using argument-dependent
58      lookup. The function `boost::asio::asio_handler_invoke()` serves as a
59      default if no user-supplied function is available.
60    ]
61  ]
62]
63
64[endsect]
65