mirror of
https://github.com/boostorg/system.git
synced 2025-11-04 09:41:52 +01:00
751 lines
33 KiB
HTML
751 lines
33 KiB
HTML
<html>
|
||
|
||
<head>
|
||
<meta http-equiv="Content-Language" content="en-us">
|
||
<meta name="GENERATOR" content="Microsoft FrontPage 5.0">
|
||
<meta name="ProgId" content="FrontPage.Editor.Document">
|
||
<meta http-equiv="Content-Type" content="text/html; charset=windows-1252">
|
||
<title>System Library Reference</title>
|
||
<link rel="stylesheet" type="text/css" href="../../../doc/html/minimal.css">
|
||
</head>
|
||
|
||
<body>
|
||
|
||
<table border="0" cellpadding="5" cellspacing="0" style="border-collapse: collapse" bordercolor="#111111" width="637">
|
||
<tr>
|
||
<td width="277">
|
||
<a href="../../../index.htm">
|
||
<img src="../../../boost.png" alt="boost.png (6897 bytes)" align="middle" width="277" height="86" border="0"></a></td>
|
||
<td width="337" align="middle">
|
||
<font size="7">System Library</font>
|
||
</td>
|
||
</tr>
|
||
</table>
|
||
|
||
<table border="0" cellpadding="5" cellspacing="0" style="border-collapse: collapse" bordercolor="#111111" bgcolor="#D7EEFF" width="100%">
|
||
<tr>
|
||
<td><a href="../../../index.htm">Boost Home</a> <a href="index.html">
|
||
Library Home</a> Tutorial <a href="reference.html">
|
||
Reference</a></td>
|
||
</tr>
|
||
</table>
|
||
|
||
<table border="1" cellpadding="5" cellspacing="0" style="border-collapse: collapse" bordercolor="#111111" align="right">
|
||
<tr>
|
||
<td width="100%" bgcolor="#D7EEFF" align="center">
|
||
<i><b>Contents</b></i></td>
|
||
</tr>
|
||
<tr>
|
||
<td width="100%" bgcolor="#E8F5FF">
|
||
<a href="#Introduction">Introduction</a><br>
|
||
<a href="#Macros">Macros</a><br>
|
||
<a href="#Header-error_code">Header <boost/system/error_code.hpp></a><br>
|
||
<a href="#Class-error_category">Class <code>error_category</code></a><br>
|
||
<a href="#Class-error_category-synopsis">Class <code>error_category</code> synopsis</a><br>
|
||
<a href="#Class-error_category-virtual-members">Class <code>error_category</code> virtual members</a><br>
|
||
<a href="#Class-error_category-non-virtual-members">Class <code>error_category</code> non-virtual members</a><br>
|
||
<a href="#Class-error_category-non-member-functions">Class <code>error_category</code>
|
||
non-member functions</a><br>
|
||
<a href="#Class-error_category-predefined-objects">Class <code>error_category</code> predefined objects</a><br>
|
||
<a href="#Class-error_code">Class <code>error_code</code></a><br>
|
||
<a href="#Class-error_code-synopsis">Class <code>error_code</code> synopsis</a><br>
|
||
<a href="#Class-error_code-constructors">Class <code>error_code</code> constructors</a><br>
|
||
<a href="#Class-error_code-modifiers">Class <code>error_code</code> modifiers</a><br>
|
||
<a href="#Class-error_code-observers">Class <code>error_code</code> observers</a><br>
|
||
<a href="#Class-error_condition</code>">Class <code>error_condition</code></a><br>
|
||
<a href="#Class-error_condition-synopsis">Class <code>error_condition</code> synopsis</a><br>
|
||
<a href="#Class-error_condition-constructors">Class <code>error_condition</code> constructors</a><br>
|
||
<a href="#Class-error_condition-modifiers">Class <code>error_condition</code> modifiers</a><br>
|
||
<a href="#Class-error_condition-observers">Class <code>error_condition</code> observers</a><br>
|
||
<a href="#Non-member-functions">Non-member functions</a><br>
|
||
<a href="#Header-system_error">Header <boost/system/system_error.hpp></a><br>
|
||
<a href="#Class-system_error">Class <code>system_error</code></a><br>
|
||
</td>
|
||
</tr>
|
||
</table>
|
||
|
||
<h2><a name="Introduction">Introduction</a></h2>
|
||
|
||
<p>This reference documentation describes components that
|
||
programs may use to report error conditions originating from the operating
|
||
system or other low-level application program interfaces.</p>
|
||
<p>Boost.System library components never change the value of <code>
|
||
errno</code>.</p>
|
||
<h2><a name="Macros">Macros</a></h2>
|
||
<p>Users may defined the following macros if desired. Sensible defaults are
|
||
provided, so users may ignore these macros if they prefer.</p>
|
||
<table border="1" cellpadding="5" cellspacing="0" style="border-collapse: collapse" bordercolor="#111111">
|
||
<tr>
|
||
<td><b><i>Macro Name</i></b></td>
|
||
<td><b><i>Default</i></b></td>
|
||
<td><b><i>Effect if defined</i></b></td>
|
||
</tr>
|
||
<tr>
|
||
<td valign="top"><code>BOOST_WINDOWS_API</code></td>
|
||
<td valign="top">Defined if Windows is detected by Boost.System's automatic configuration
|
||
code, otherwise not defined.</td>
|
||
<td valign="top">Implementation uses the Microsoft Windows native
|
||
application program interface (API).</td>
|
||
</tr>
|
||
<tr>
|
||
<td valign="top"><code>BOOST_POSIX_API</code></td>
|
||
<td valign="top">Defined if Windows is not detected by Boost.System's automatic configuration
|
||
code.</td>
|
||
<td valign="top">Implementation uses the POSIX native
|
||
application program interface (API).</td>
|
||
</tr>
|
||
<tr>
|
||
<td valign="top"><code>BOOST_SYSTEM_DYN_LINK</code></td>
|
||
<td valign="top">Defined if <code>BOOST_ALL_DYN_LINK</code> is defined,
|
||
otherwise not defined.</td>
|
||
<td valign="top">Boost.System library is dynamically linked. If not defined,
|
||
static linking is assumed.</td>
|
||
</tr>
|
||
<tr>
|
||
<td valign="top"><code>BOOST_SYSTEM_NO_LIB</code></td>
|
||
<td valign="top">Defined if <code>BOOST_ALL_NO_LIB</code> is defined,
|
||
otherwise not defined.</td>
|
||
<td valign="top">Boost.System library does not use the Boost auto-link
|
||
facility.</td>
|
||
</tr>
|
||
<tr>
|
||
<td valign="top"><code>BOOST_SYSTEM_NO_DEPRECATED</code></td>
|
||
<td valign="top">Not defined.</td>
|
||
<td valign="top">Deprecated features are excluded.</td>
|
||
</tr>
|
||
</table>
|
||
<h2><a name="Header-error_code">Header <boost/system/error_code.hpp></a></h2>
|
||
<h3><boost/system/error_code.hpp> synopsis</h3>
|
||
<blockquote>
|
||
<pre>namespace boost
|
||
{
|
||
namespace system
|
||
{
|
||
class <a href="#Class-error_category">error_category</a>;
|
||
class <a href="#Class-error_code">error_code</a>;
|
||
class <a href="#Class-error_condition">error_condition</a>;
|
||
|
||
// "Concept" helpers
|
||
template< class T="" >
|
||
struct is_error_code_enum { static const bool value = false; };
|
||
|
||
template< class T="" >
|
||
struct is_error_condition_enum { static const bool value = false; };
|
||
|
||
// portable error_conditions
|
||
namespace posix_error
|
||
{
|
||
enum posix_errno
|
||
{
|
||
success = 0,
|
||
address_family_not_supported, //EAFNOSUPPORT
|
||
address_in_use, //EADDRINUSE
|
||
address_not_available, //EADDRNOTAVAIL
|
||
already_connected, //EISCONN
|
||
argument_list_too_long, //E2BIG
|
||
argument_out_of_domain, //EDOM
|
||
bad_address, //EFAULT
|
||
bad_file_descriptor, //EBADF
|
||
bad_message, //EBADMSG
|
||
broken_pipe, //EPIPE
|
||
connection_aborted, //ECONNABORTED
|
||
connection_already_in_progress, //EALREADY
|
||
connection_refused, //ECONNREFUSED
|
||
connection_reset, //ECONNRESET
|
||
cross_device_link, //EXDEV
|
||
destination_address_required, //EDESTADDRREQ
|
||
device_or_resource_busy, //EBUSY
|
||
directory_not_empty, //ENOTEMPTY
|
||
executable_format_error, //ENOEXEC
|
||
file_exists, //EEXIST
|
||
file_too_large, //EFBIG
|
||
filename_too_long, //ENAMETOOLONG
|
||
function_not_supported, //ENOSYS
|
||
host_unreachable, //EHOSTUNREACH
|
||
identifier_removed, //EIDRM
|
||
illegal_byte_sequence, //EILSEQ
|
||
inappropriate_io_control_operation,//ENOTTY
|
||
interrupted, //EINTR
|
||
invalid_argument, //EINVAL
|
||
invalid_seek, //ESPIPE
|
||
io_error, //EIO
|
||
is_a_directory, //EISDIR
|
||
message_size, //EMSGSIZE
|
||
network_down, //ENETDOWN
|
||
network_reset, //ENETRESET
|
||
network_unreachable, //ENETUNREACH
|
||
no_buffer_space, //ENOBUFS
|
||
no_child_process, //ECHILD
|
||
no_link, //ENOLINK
|
||
no_lock_available, //ENOLCK
|
||
no_message_available, //ENODATA
|
||
no_message, //ENOMSG
|
||
no_protocol_option, //ENOPROTOOPT
|
||
no_space_on_device, //ENOSPC
|
||
no_stream_resources, //ENOSR
|
||
no_such_device_or_address, //ENXIO
|
||
no_such_device, //ENODEV
|
||
no_such_file_or_directory, //ENOENT
|
||
no_such_process, //ESRCH
|
||
not_a_directory, //ENOTDIR
|
||
not_a_socket, //ENOTSOCK
|
||
not_a_stream, //ENOSTR
|
||
not_connected, //ENOTCONN
|
||
not_enough_memory, //ENOMEM
|
||
not_supported, //ENOTSUP
|
||
operation_canceled, //ECANCELED
|
||
operation_in_progress, //EINPROGRESS
|
||
operation_not_permitted, //EPERM
|
||
operation_not_supported, //EOPNOTSUPP
|
||
operation_would_block, //EWOULDBLOCK
|
||
owner_dead, //EOWNERDEAD
|
||
permission_denied, //EACCES
|
||
protocol_error, //EPROTO
|
||
protocol_not_supported, //EPROTONOSUPPORT
|
||
read_only_file_system, //EROFS
|
||
resource_deadlock_would_occur, //EDEADLK
|
||
resource_unavailable_try_again, //EAGAIN
|
||
result_out_of_range, //ERANGE
|
||
state_not_recoverable, //ENOTRECOVERABLE
|
||
stream_timeout, //ETIME
|
||
text_file_busy, //ETXTBSY
|
||
timed_out, //ETIMEDOUT
|
||
too_many_files_open_in_system, //ENFILE
|
||
too_many_files_open, //EMFILE
|
||
too_many_links, //EMLINK
|
||
too_many_synbolic_link_levels, //ELOOP
|
||
value_too_large, //EOVERFLOW
|
||
wrong_protocol_type //EPROTOTYPE
|
||
};
|
||
|
||
} // namespace posix_error
|
||
|
||
template<> struct is_error_condition_enum<posix::posix_errno><posix_error::posix_errno>
|
||
{ static const bool value = true; };
|
||
|
||
bool operator==( const error_code & lhs, const error_code & rhs );
|
||
bool operator==( const error_code & code, const error_condition & condition );
|
||
bool operator==( const error_condition & condition, const error_code & code );
|
||
bool operator==( const error_condition & lhs, const error_condition & rhs );
|
||
|
||
bool operator!=( const error_code & lhs, const error_code & rhs );
|
||
bool operator!=( const error_code & code, const error_condition & condition );
|
||
bool operator!=( const error_condition & condition, const error_code & code );
|
||
bool operator!=( const error_condition & lhs, const error_condition & rhs );
|
||
|
||
bool operator<( const error_code & lhs, const error_code & rhs );
|
||
bool operator<( const error_condition & lhs, const error_condition & rhs );
|
||
|
||
error_code make_error_code( posix_error::posix_errno e );
|
||
error_condition make_error_condition( posix_error::posix_errno e );
|
||
|
||
template <class charT, class traits>
|
||
std::basic_ostream<charT,traits>&
|
||
operator<<( basic_ostream<charT,traits>& os, const error_code & ec );
|
||
|
||
size_t hash_value( const error_code & ec );
|
||
}
|
||
}</pre>
|
||
</blockquote>
|
||
<p>The value of each<code> posix_errno</code> constant shall be the same as the
|
||
value of the <code><cerrno></code> macro shown in the above synopsis.</p>
|
||
<p>Users may specialize <code>is_error_code_enum</code> and <code>
|
||
is_error_condition_enum</code> templates to indicate that a type is eligible for
|
||
class <code>error_code</code> and <code>error_condition</code> automatic
|
||
conversions respectively.</p>
|
||
|
||
<h2><a name="Class-error_category">Class <code>error_category</code></a></h2>
|
||
<p>The class <code>error_category</code> defines the base class for types used
|
||
to identify the source and encoding of a particular category of error code.</p>
|
||
<p><i>[Note:</i> Classes may be derived from <code>error_category</code>
|
||
to support additional categories of errors. <i>--end note]</i></p>
|
||
<p>The class <code>error_category</code> serves as a base class for types used
|
||
to identify the source and encoding of a particular category of error code.
|
||
Classes may be derived from <code>error_category</code> to support categories of
|
||
errors in addition to those defined in the Boost System library. Such classes
|
||
shall behave as specified in this subclause. [<i> Note:</i> <code>error_category</code>
|
||
objects are passed by reference, and two such objects are equal if they have the
|
||
same address. This means that applications using custom <code>error_category</code>
|
||
types should create a single object of each such type. <i><EFBFBD>end note</i> ]</p>
|
||
<h3><a name="Class-error_category-synopsis">Class <code>error_category</code> synopsis</a></h3>
|
||
<blockquote>
|
||
<pre>namespace boost
|
||
{
|
||
namespace system
|
||
{
|
||
class error_category : public noncopyable
|
||
{
|
||
public:
|
||
virtual ~error_category();
|
||
|
||
virtual const char * name() const = 0;
|
||
virtual string message( error_code::value_type ev ) const = 0;
|
||
virtual error_condition default_error_condition( int ev ) const;
|
||
virtual bool equivalent( int code, const error_condition & condition ) const;
|
||
virtual bool equivalent( const error_code & code, int condition ) const;
|
||
|
||
bool operator==( const error_category & rhs ) const;
|
||
bool operator!=( const error_category & rhs ) const;
|
||
bool operator< ( const error_category & rhs ) const;
|
||
};
|
||
|
||
const error_category & get_system_category();
|
||
const error_category & get_posix_category();
|
||
|
||
static const error_category & system_category = get_system_category();
|
||
static const error_category & posix_category = get_posix_category();
|
||
}
|
||
}</pre>
|
||
</blockquote>
|
||
<h3><a name="Class-error_category-virtual-members">Class <code>error_category</code> virtual members</a></h3>
|
||
<p>Classes derived from <code>error_category</code> shall behave as specified in
|
||
this subclause.</p>
|
||
<pre>virtual const char * name() const=0;</pre>
|
||
<blockquote>
|
||
<p><i>Returns: </i>a string naming the error category.</p>
|
||
<p><i>Throws:</i> Nothing.</p>
|
||
</blockquote>
|
||
<pre>virtual string message( error_code::value_type ev ) const=0;</pre>
|
||
<blockquote>
|
||
<p><i>Returns:</i> A string that describes the error denoted by
|
||
<code>ev</code>.</p>
|
||
<p><i>Throws:</i> Nothing.</p>
|
||
</blockquote>
|
||
<p><code>virtual error_condition default_error_condition( int ev ) const;</code></p>
|
||
<blockquote>
|
||
<p><i>Returns:</i> <code>error_condition( ev, *this )</code>.</p>
|
||
<blockquote>
|
||
<p> [<i>--Note:</i> Derived classes will typically convert <code>ev</code>
|
||
to some portable <code>error_category</code>, such as <code>posix_category</code>,
|
||
and return it as an <code>error_condition</code> for that category. <i>--end
|
||
note</i>]</p>
|
||
</blockquote>
|
||
<p><i>Throws:</i> Nothing.</p>
|
||
</blockquote>
|
||
<p><code>virtual bool equivalent( int code, const error_condition &
|
||
condition )
|
||
const;</code></p>
|
||
<blockquote>
|
||
<p><i>Returns:</i> <code>default_error_condition( code ) == condition</code>.</p>
|
||
<p><i>Throws:</i> Nothing.</p>
|
||
</blockquote>
|
||
<p><code>virtual bool equivalent( const error_code & code, int condition ) const;</code></p>
|
||
<blockquote>
|
||
<p><i>Returns:</i> <code>*this == code.category() && code.value() == condition</code>.</p>
|
||
<p><i>Throws:</i> Nothing.</p>
|
||
</blockquote>
|
||
<h3><a name="Class-error_category-non-virtual-members">Class <code>error_category</code> non-virtual members</a></h3>
|
||
<p><code>bool operator==( const error_category & rhs ) const;</code></p>
|
||
<blockquote>
|
||
<p><i>Returns:</i> <code>this == &rhs</code>.</p>
|
||
</blockquote>
|
||
<p><code>bool operator!=( const error_category & rhs ) const;</code></p>
|
||
<blockquote>
|
||
<p><i>Returns:</i> <code>this != &rhs</code>.</p>
|
||
</blockquote>
|
||
|
||
<pre>bool operator<( const error_category & rhs ) const;</pre>
|
||
<blockquote>
|
||
<p><i>Returns:</i> <code>std::less<const error_category*>()( this, &rhs )</code>.</p>
|
||
<blockquote>
|
||
<p><i>[Note:</i> <code>std::less</code> provides a total ordering for
|
||
pointers. <i>--end note]</i></p>
|
||
</blockquote>
|
||
<p><i>Throws:</i> Nothing.</p>
|
||
</blockquote>
|
||
<h3><a name="Class-error_category-non-member-functions">Class <code>error_category</code>
|
||
non-member functions</a></h3>
|
||
<pre>const error_category & get_system_category();</pre>
|
||
<blockquote>
|
||
<p><i>Returns:</i> A reference to a <code>error_category</code> object
|
||
identifying errors originating from the operating system.</p>
|
||
<p><i>Throws:</i> Nothing.</p>
|
||
</blockquote>
|
||
<pre>const error_category & get_posix_category();</pre>
|
||
<blockquote>
|
||
<p><i>Returns:</i> A reference to a <code>error_category</code> object
|
||
identifying portable error conditions.</p>
|
||
<p><i>Throws:</i> Nothing.</p>
|
||
</blockquote>
|
||
<h3><a name="Class-error_category-predefined-objects">Class <code>error_category</code>
|
||
predefined objects</a></h3>
|
||
<p>Predefined objects <code>system_category</code>
|
||
and <code>posix_category</code> identify operating system error codes and portable error conditions, respectively.</p>
|
||
<h2><a name="Class-error_code">Class <code>
|
||
error_code</code></a></h2>
|
||
<p>The class <code>error_code</code> describes an object used to hold error code
|
||
values, such as those originating from the operating<br>
|
||
system or other low-level application program interfaces. <i>[ Note: </i>Class
|
||
<code>error_code</code> is an adjunct to error reporting by<br>
|
||
exception. <i><EFBFBD>end note ]</i></p>
|
||
<h3><a name="Class-error_code-synopsis">Class <code>
|
||
error_code</code> synopsis</a></h3>
|
||
<blockquote>
|
||
<pre>namespace boost
|
||
{
|
||
namespace system
|
||
{
|
||
class error_code {
|
||
public:
|
||
|
||
// constructors:
|
||
error_code();
|
||
error_code( val, const error_category & cat );
|
||
template <class <code>ErrorCodeEnum</code>>
|
||
error_code(<code> errorCodeEnum</code> e,
|
||
typename enable_if<is_error_code_enum<<code>ErrorCodeEnum</code>> >::type* = 0);
|
||
|
||
// modifiers:
|
||
void assign( int val, const error_category & cat );
|
||
template<typename <code>ErrorCodeEnum</code>>
|
||
typename enable_if<is_error_code_enum<<code>ErrorCodeEnum</code>>, error_code>::type &
|
||
operator=( <code>ErrorCodeEnum</code> val );;
|
||
void clear();
|
||
|
||
// observers:
|
||
int value() const;
|
||
cont error_category & category() const;
|
||
error_condition default_error_condition() const;
|
||
string message() const;
|
||
operator unspecified-bool-type() const;
|
||
|
||
private:
|
||
int val_; // <i>exposition only</i>
|
||
const error_category & cat_; // <i>exposition only</i>
|
||
};
|
||
}
|
||
}</pre>
|
||
</blockquote>
|
||
<h3><a name="Class-error_code-constructors">Class <code>
|
||
error_code</code> constructors</a></h3>
|
||
<pre>error_code();</pre>
|
||
<blockquote>
|
||
<p><i>Effects: </i>Constructs an object of type <code>error_code</code>.</p>
|
||
<p><i>Postconditions:</i> <code>val_ == 0 && cat_ == &system_category</code>.</p>
|
||
<p><i>Throws:</i> Nothing.</p>
|
||
</blockquote>
|
||
<pre>error_code( int val, const error_category & cat );</pre>
|
||
<blockquote>
|
||
<p><i>Effects: </i>Constructs an object of type <code>error_code</code>.</p>
|
||
<p><i>Postconditions:</i> <code>val_ == val && cat_ == &cat</code>.</p>
|
||
<p><i>Throws:</i> Nothing.</p>
|
||
</blockquote>
|
||
<pre>template <class <code>ErrorCodeEnum</code>>
|
||
error_code(<code> errorCodeEnum</code> val,
|
||
typename enable_if<is_error_code_enum<<code>ErrorCodeEnum</code>> >::type* = 0);</pre>
|
||
<blockquote>
|
||
<p><i>Effects: </i>Constructs an object of type <code>error_code</code>.</p>
|
||
<p><i>Postconditions:</i> <code>*this == make_error_code( val )</code>.</p>
|
||
<p><i>Throws:</i> Nothing.</p>
|
||
</blockquote>
|
||
<h3><a name="Class-error_code-modifiers">Class <code>
|
||
error_code</code> modifiers</a></h3>
|
||
<pre>void assign( int val, const error_category & cat );</pre>
|
||
<blockquote>
|
||
<p><i>Postconditions:</i> <code>val_ == val && cat_ == cat</code>.</p>
|
||
<p><i>Throws:</i> Nothing.</p>
|
||
</blockquote>
|
||
<pre>template<typename <code>ErrorCodeEnum</code>>
|
||
typename enable_if<is_error_code_enum<<code>ErrorCodeEnum</code>>, error_code>::type &
|
||
operator=( <code>ErrorCodeEnum</code> val );</pre>
|
||
<blockquote>
|
||
<p><i>Postconditions:</i> <code>*this == make_error_code( val )</code>.</p>
|
||
<p><i>Throws:</i> Nothing.</p>
|
||
</blockquote>
|
||
<p><code>void clear();</code></p>
|
||
<blockquote>
|
||
<p><i>postcondition:</i> <code>value() == 0 && category() == posix_category</code></p>
|
||
</blockquote>
|
||
<h3><a name="Class-error_code-observers">Class <code>
|
||
error_code</code> observers</a></h3>
|
||
<p><code>int value() const;</code></p>
|
||
<blockquote>
|
||
<p><i>Returns:</i> <code>val_</code>.</p>
|
||
<p><i>Throws:</i> Nothing.</p>
|
||
</blockquote>
|
||
<p><code>error_category category() const;</code></p>
|
||
<blockquote>
|
||
<p><i>Returns:</i> <code>cat_</code>.</p>
|
||
<p><i>Throws:</i> Nothing.</p>
|
||
</blockquote>
|
||
<pre>error_condition default_error_condition() const;</pre>
|
||
<blockquote>
|
||
<p><i>Returns:</i> <code>category().default_error_condition( value())</code>.</p>
|
||
<p><i>Throws:</i> Nothing.</p>
|
||
</blockquote>
|
||
<p><code>string message() const;</code></p>
|
||
<blockquote>
|
||
<p><i>Returns:</i> <code>category().message( value())</code>.</p>
|
||
<p><i>Throws:</i> Nothing.</p>
|
||
</blockquote>
|
||
<p><code>operator <i>unspecified-bool-type</i>() const;</code></p>
|
||
<blockquote>
|
||
<p><i>Returns:</i> if <code>value() != value_type()</code>, returns a value that will evaluate
|
||
<code>true</code> in a boolean context; otherwise, returns a value that will
|
||
evaluate <code>false</code> in a boolean context. The value type returned shall
|
||
not be convertible to <code>int</code>.</p>
|
||
<p><i>Throws:</i> nothing.</p>
|
||
<p><i>[Note: </i>This conversion can be used in contexts where a <code>bool</code>
|
||
is expected ( e.g., an <code>if</code> condition ); however, implicit conversions
|
||
( e.g., to <code>int</code>) that can occur with <code>bool</code> are not
|
||
allowed, eliminating some sources of user error. One possible implementation
|
||
choice for this type is pointer-to-member. <i>--end note ]</i></p>
|
||
</blockquote>
|
||
<h2><a name="Class-error_condition">Class <code>error_condition</code></a></h2>
|
||
<p>The class <code>error_condition</code> describes an object used to hold
|
||
values identifying error conditions. <i>[ Note: </i><code>error_condition</code>
|
||
values are portable abstractions, while <code>error_code</code> values are
|
||
implementation specific. <i>--end note ]</i></p>
|
||
<h3><a name="Class-error_condition-synopsis">Class <code>error_condition</code> synopsis</a></h3>
|
||
<blockquote>
|
||
<pre>namespace boost
|
||
{
|
||
namespace system
|
||
{
|
||
class error_condition
|
||
{
|
||
public:
|
||
|
||
// constructors:
|
||
error_condition();
|
||
error_condition( int val, const error_category & cat );
|
||
template <class ErrorConditionEnum>
|
||
error_condition( errorConditionEnum val,
|
||
typename enable_if<is_error_condition_enum<ErrorConditionEnum> >::type* = 0 );
|
||
|
||
// modifiers:
|
||
void assign( int val, const error_category & cat );
|
||
template<typename ErrorConditionEnum>
|
||
typename enable_if<is_error_condition_enum<ErrorConditionEnum>, error_code>::type &
|
||
operator=( ErrorConditionEnum val );
|
||
void clear();
|
||
|
||
// observers:
|
||
int value() const;
|
||
const error_category & category() const;
|
||
string message() const;
|
||
operator unspecified-bool-type () const;
|
||
|
||
private:
|
||
int val_; // <i>exposition only</i>
|
||
const error_category & cat_; // <i>exposition only</i>
|
||
};
|
||
}
|
||
}</pre>
|
||
</blockquote>
|
||
<h3><a name="Class-error_condition-constructors">Class <code>error_condition</code>
|
||
constructors</a></h3>
|
||
<pre>error_condition(); </pre>
|
||
<blockquote>
|
||
<p><i>Effects:</i> Constructs an object of type <code>error_condition</code>.</p>
|
||
<p><i>Postconditions:</i> <code>val_ == 0 and cat_ == posix_category</code>.</p>
|
||
<p><i>Throws:</i> Nothing.</p>
|
||
</blockquote>
|
||
<pre>error_condition( value_type val, const error_category & cat );</pre>
|
||
<blockquote>
|
||
<p><i>Effects: </i>Constructs an object of type error_condition.</p>
|
||
<p><i>Postconditions:</i> <code>val_ == val and cat_ == cat</code>.</p>
|
||
<p><i>Throws:</i> Nothing.</p>
|
||
</blockquote>
|
||
<pre>template <class ErrorConditionEnum>
|
||
error_condition( errorConditionEnum val,
|
||
typename enable_if<is_error_condition_enum<ErrorConditionEnum> >::type* = 0 );</pre>
|
||
<blockquote>
|
||
<p><i>Effects:</i> Constructs an object of type <code>error_condition</code>.</p>
|
||
<p><i>Postconditions:</i> <code>*this == make_error_condition( val )</code>.</p>
|
||
<p><i>Throws:</i> Nothing.</p>
|
||
</blockquote>
|
||
<h3><a name="Class-error_condition-modifiers">Class <code>error_condition</code>
|
||
modifiers</a></h3>
|
||
<pre>void assign( value_type val, const error_category & cat ); </pre>
|
||
<blockquote>
|
||
<p><i>Postconditions:</i> <code>val_ == val and cat_ == cat</code>. </p>
|
||
<p><i>Throws:</i> Nothing.</p>
|
||
</blockquote>
|
||
<pre>template<typename ErrorConditionEnum>
|
||
typename enable_if<is_error_condition_enum<ErrorConditionEnum>, error_code>::type &
|
||
operator=( ErrorConditionEnum val );</pre>
|
||
<blockquote>
|
||
<p><i>Postconditions:</i> <code>*this == make_error_condition( val )</code>.</p>
|
||
<p><i>Throws:</i> Nothing.</p>
|
||
</blockquote>
|
||
<p><code>void clear();</code></p>
|
||
<blockquote>
|
||
<p><i>postcondition:</i> <code>value() == 0 && category() == posix_category</code></p>
|
||
</blockquote>
|
||
<h3><a name="Class-error_condition-observers">Class <code>error_condition</code>
|
||
observers</a></h3>
|
||
<pre>value_type value() const;</pre>
|
||
<blockquote>
|
||
<p><i>Returns:</i> <code>val_</code>.</p>
|
||
<p><i>Throws:</i> Nothing</p>
|
||
</blockquote>
|
||
<pre>const error_category & category() const;</pre>
|
||
<blockquote>
|
||
<p><i>Returns:</i> <code>cat_</code>.</p>
|
||
<p>Throws: Nothing.</p>
|
||
</blockquote>
|
||
<pre>string message() const;</pre>
|
||
<blockquote>
|
||
<p><i>Returns:</i> <code>category().message( value() )</code>.</p>
|
||
<p><i>Throws:</i> Nothing.</p>
|
||
</blockquote>
|
||
<pre>operator unspecified-bool-type () const;</pre>
|
||
<blockquote>
|
||
<p><i>Returns: </i>If <code>value() != 0</code>, returns a value that will
|
||
evaluate <code>true</code> in a boolean context; otherwise, returns a value
|
||
that will evaluate <code>false</code>. The return type shall not be
|
||
convertible to <code>int</code>. </p>
|
||
<p><i>Throws:</i> Nothing.</p>
|
||
<p><i> [ Note:</i> This conversion can be used in contexts where a <code>bool</code>
|
||
is expected ( e.g., an if condition ); however, implicit conversions ( e.g., to
|
||
<code>int</code>) that can occur with <code>bool</code> are not allowed,
|
||
eliminating some sources of user error. One possible implementation choice for
|
||
this type is pointer to member. <i>--end note</i> <i>]</i></p>
|
||
</blockquote>
|
||
<h2><a name="Non-member-functions">Non-member functions</a></h2>
|
||
<pre>bool operator==( const error_code & lhs, const error_code & rhs );</pre>
|
||
<blockquote>
|
||
<p><i>Returns:</i> <code>lhs.category() == rhs.category() && lhs.value() ==
|
||
rhs.value()</code>.</p>
|
||
<p><i>Throws: </i>Nothing.</p>
|
||
</blockquote>
|
||
<pre>bool operator==( const error_code & code, const error_condition & condition );
|
||
bool operator==( const error_condition & condition, const error_code & code );</pre>
|
||
<blockquote>
|
||
<p><i>Returns:</i> <code>code.category().equivalent( code.value(), condition )<br>
|
||
|| condition.category().equivalent( code, condition.value() )</code>.</p>
|
||
<p><i>Throws: </i>Nothing.</p>
|
||
</blockquote>
|
||
<pre>bool operator==( const error_condition & lhs, const error_condition & rhs );</pre>
|
||
<blockquote>
|
||
<p><i>Returns:</i> <code>lhs.category() == rhs.category() && lhs.value() ==
|
||
rhs.value()</code>.</p>
|
||
<p><i>Throws: </i>Nothing.</p>
|
||
</blockquote>
|
||
<pre>bool operator!=( const error_code & lhs, const error_code & rhs );</pre>
|
||
<blockquote>
|
||
<p><i>Returns:</i> <code>!(lhs == rhs )</code>.</p>
|
||
<p><i>Throws: </i>Nothing.</p>
|
||
</blockquote>
|
||
<pre>bool operator!=( const error_code & code, const error_condition & condition );
|
||
bool operator!=( const error_condition & condition, const error_code & code );</pre>
|
||
<blockquote>
|
||
<p><i>Returns:</i><code> !( code == condition )</code>.</p>
|
||
<p><i>Throws: </i>Nothing.</p>
|
||
</blockquote>
|
||
<pre>bool operator!=( const error_condition & lhs, const error_condition & rhs );</pre>
|
||
<blockquote>
|
||
<p><i>Returns:</i> <code>!(lhs == rhs )</code>.</p>
|
||
<p><i>Throws: </i>Nothing.</p>
|
||
</blockquote>
|
||
<pre>bool operator<( const error_code & lhs, const error_code & rhs );</pre>
|
||
<blockquote>
|
||
<p><i>Returns:</i> <code>lhs.category() < rhs.category()<br>
|
||
|| (lhs.category() == rhs.category() && lhs.value() < rhs.value())</code>.</p>
|
||
<p><i>Throws: </i>Nothing.</p>
|
||
</blockquote>
|
||
<pre>bool operator<( const error_condition & lhs, const error_condition & rhs );</pre>
|
||
<blockquote>
|
||
<p><i>Returns:</i> <code>lhs.category() < rhs.category()<br>
|
||
|| (lhs.category() == rhs.category() && lhs.value() < rhs.value())</code>.</p>
|
||
<p><i>Throws: </i>Nothing.</p>
|
||
</blockquote>
|
||
<pre>error_code make_error_code( posix_error::posix_errno e );</pre>
|
||
<blockquote>
|
||
<p><i>Returns:</i> <code>error_code( e, posix_category)</code>.</p>
|
||
</blockquote>
|
||
<pre>error_condition make_error_condition( posix_error::posix_errno e );</pre>
|
||
<blockquote>
|
||
<p><i>Returns:</i> <code>error_condition( e, posix_category)</code>.</p>
|
||
</blockquote>
|
||
|
||
<pre>template <class charT, class traits>
|
||
std::basic_ostream<charT,traits>&
|
||
operator<<( basic_ostream<charT,traits>& os, const error_code & ec );</pre>
|
||
<blockquote>
|
||
<p><i>Effects:</i> <code>os << ec.category().name() << ':' << ec.value()</code>.</p>
|
||
<p><i>Returns:</i> <code>os</code>.</p>
|
||
</blockquote>
|
||
<pre>size_t <a name="hash_value">hash_value</a>( const error_code & ec );</pre>
|
||
<blockquote>
|
||
<p><i>Returns: </i> A hash value representing <code>ec</code>.</p>
|
||
</blockquote>
|
||
|
||
<h2><a name="Header-system_error">Header <boost/system/system_error.hpp></a></h2>
|
||
|
||
<h3><a name="Class-system_error">Class <code>
|
||
system_error</code></a></h3>
|
||
<p>The class <code>system_error</code> describes an exception object used to
|
||
report error conditions that have an associated error code. Such error
|
||
conditions typically originate from the operating system or other low-level
|
||
application program interfaces.</p>
|
||
<blockquote>
|
||
<pre>namespace boost
|
||
{
|
||
namespace system
|
||
{
|
||
class system_error : public std::runtime_error
|
||
{
|
||
public:
|
||
system_error( error_code ec );
|
||
system_error( error_code ec, const std::string & what_arg );
|
||
system_error( error_code::value_type ev, const error_category & ecat,
|
||
const std::string & what_arg );
|
||
system_error( error_code::value_type ev, const error_category & ecat);
|
||
|
||
const error_code & code() const throw();
|
||
const char * what() const throw();
|
||
};
|
||
}
|
||
}</pre>
|
||
</blockquote>
|
||
<pre>system_error( error_code ec );</pre>
|
||
<blockquote>
|
||
<p><i>Effects:</i> Constructs an object of class <code>system_error</code>.</p>
|
||
<p><i>Postcondition:</i> <code>code() == ec <br>
|
||
&& std::strcmp( this->runtime_error::what(), "" ) == 0</code></p>
|
||
</blockquote>
|
||
<pre>system_error( error_code ec, const std::string & what_arg );</pre>
|
||
<blockquote>
|
||
<p><i>Effects:</i> Constructs an object of class <code>system_error</code>.</p>
|
||
<p><i>Postcondition:</i> <code>code() == ec <br>
|
||
&& std::strcmp( this->runtime_error::what(), what_arg.c_str() ) == 0</code></p>
|
||
</blockquote>
|
||
<pre>system_error( error_code::value_type ev, const error_category & ecat,
|
||
const std::string & what_arg );</pre>
|
||
<blockquote>
|
||
<p><i>Effects:</i> Constructs an object of class <code>system_error</code>.</p>
|
||
<p><i>Postcondition:</i> <code>code() == error_code( ev, ecat )<br>
|
||
&& std::strcmp( this->runtime_error::what(), what_arg.c_str() ) == 0</code></p>
|
||
</blockquote>
|
||
<pre>system_error( error_code::value_type ev, const error_category & ecat );</pre>
|
||
<blockquote>
|
||
<p><i>Effects:</i> Constructs an object of class <code>system_error</code>.</p>
|
||
<p><i>Postcondition:</i> <code>code() == error_code( ev, ecat )<br>
|
||
&& std::strcmp( this->runtime_error::what(), "" ) == 0</code></p>
|
||
</blockquote>
|
||
<pre>const error_code & code() const;</pre>
|
||
<blockquote>
|
||
<p><i>Returns:</i> <code>ec</code> or <code>error_code( ev, ecat )</code>, from
|
||
the constructor, as appropriate.</p>
|
||
</blockquote>
|
||
<pre>const char * what() const;</pre>
|
||
<blockquote>
|
||
<p><i>Returns: </i>A string incorporating <code>
|
||
this->runtime_error::what()</code> and <code>
|
||
code.message()</code>.</p>
|
||
</blockquote>
|
||
<hr>
|
||
|
||
<p><EFBFBD> Copyright Beman Dawes, 2006, 2007<br>
|
||
Distributed under the Boost Software License, Version 1.0. See
|
||
<a href="http://www.boost.org/LICENSE_1_0.txt">www.boost.org/LICENSE_1_0.txt</a></p>
|
||
|
||
<p>Revised
|
||
<!--webbot bot="Timestamp" S-Type="EDITED" S-Format="%B %d, %Y" startspan -->November 12, 2007<!--webbot bot="Timestamp" endspan i-checksum="39581" --> </font>
|
||
</p>
|
||
|
||
</body>
|
||
|
||
</html> |