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- <i><b>Contents</b></i></td>
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- <tr>
- <td width="100%" bgcolor="#E8F5FF">
- <a href="#Introduction">Introduction</a><br>
- <a href="#Macros">Macros</a><br>
- <a href="#Deprecated-names">Deprecated names</a><br>
- <a href="#Breaking-changes">Breaking changes</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">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="#throws-object"><code>throws</code> object</a><br>
- <a href="#Semantics-of-throws">Semantics of <code>throws</code> object</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" height="368">
- <tr>
- <td height="16"><b><i>Macro Name</i></b></td>
- <td height="16"><b><i>Default</i></b></td>
- <td height="16"><b><i>Effect if defined</i></b></td>
- </tr>
- <tr>
- <td valign="top" height="64"><code>BOOST_SYSTEM_DYN_LINK</code></td>
- <td valign="top" height="64">Defined if <code>BOOST_ALL_DYN_LINK</code> is defined,
- otherwise not defined.</td>
- <td valign="top" height="64">Boost.System library is dynamically linked. If not defined,
- static linking is assumed.</td>
- </tr>
- <tr>
- <td valign="top" height="47"><code>BOOST_SYSTEM_NO_LIB</code></td>
- <td valign="top" height="47">Defined if <code>BOOST_ALL_NO_LIB</code> is defined,
- otherwise not defined.</td>
- <td valign="top" height="47">Boost.System library does not use the Boost auto-link
- facility.</td>
- </tr>
- <tr>
- <td valign="top" height="32"><code>BOOST_SYSTEM_NO_DEPRECATED</code></td>
- <td valign="top" height="32">Not defined.</td>
- <td valign="top" height="32">Deprecated features are excluded.</td>
- </tr>
- </table>
- <h2><a name="Deprecated-names">Deprecated names</a></h2>
- <p>In the process of adding Boost.System to C++0x standard library, the C++
- committee changed some
- names. To ease transition, Boost.System deprecates the old
- names, but continues to provide them unless macro <code>BOOST_SYSTEM_NO_DEPRECATED</code>
- is defined.</p>
- <table border="1" cellpadding="5" cellspacing="1" style="border-collapse: collapse" bordercolor="#111111">
- <tr>
- <td><b><i>Old usage, now deprecated</i></b></td>
- <td><b><i>Replacement</i></b></td>
- </tr>
- <tr>
- <td><code>get_generic_category()</code></td>
- <td><code>generic_category()</code></td>
- </tr>
- <tr>
- <td><code>get_system_category()</code></td>
- <td><code>system_category()</code></td>
- </tr>
- <tr>
- <td><code>namespace posix</code></td>
- <td><code>namespace errc</code></td>
- </tr>
- <tr>
- <td><code>namespace posix_error</code></td>
- <td><code>namespace errc</code></td>
- </tr>
- <tr>
- <td><code>enum posix_errno</code></td>
- <td><code>enum errc_t</code></td>
- </tr>
- <tr>
- <td><code>get_posix_category()</code></td>
- <td><code>generic_category()</code></td>
- </tr>
- <tr>
- <td><code>posix_category</code></td>
- <td><code>generic_category()</code></td>
- </tr>
- <tr>
- <td><code>errno_ecat</code></td>
- <td><code>generic_category()</code></td>
- </tr>
- <tr>
- <td><code>native_ecat</code></td>
- <td><code>system_category()</code></td>
- </tr>
- </table>
- <h2><a name="Breaking-changes">Breaking changes</a></h2>
- <p>Two static consts are replaced by functions. These are breaking changes best
- fixed by globally adding () to these names to turn them into function calls.</p>
- <table border="1" cellpadding="5" cellspacing="1" style="border-collapse: collapse" bordercolor="#111111">
- <tr>
- <td><b><i>Old usage, now broken</i></b></td>
- <td><b><i>Replacement</i></b></td>
- </tr>
- <tr>
- <td><code>generic_category</code></td>
- <td><code>generic_category()</code></td>
- </tr>
- <tr>
- <td><code>system_category</code></td>
- <td><code>system_category()</code></td>
- </tr>
- </table>
- <p>User-defined BOOST_POSIX_API and BOOST_WINDOWS_API macros are no longer supported.</p>
- <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; };
- // generic error_conditions
- namespace errc
- {
- enum errc_t
- {
- 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 errc
- template<> struct is_error_condition_enum<posix::posix_errno><errc::errc_t>
- { static const bool value = true; };
- // <a href="#Non-member-functions">non-member functions</a>
- 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( errc::errc_t e );
- error_condition make_error_condition( errc::errc_t 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> errc_t</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>容nd 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( int 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 & system_category();
- const error_category & generic_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( int 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 dir="ltr"> [<i>--Note:</i> Derived classes will typically convert <code>ev</code>
- to some portable <code>error_category</code>, such as <code>generic_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 & 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 & generic_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>
- <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>容nd 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 );
- // modifiers:
- void assign( int val, const error_category & cat );
- template<typename <code>ErrorCodeEnum</code>>
- error_code & 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 );</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>
- <p><i>Remarks:</i> This constructor shall not participate in overload
- resolution unless <code>is_error_code_enum<ErrorCodeEnum>::value</code> is
- <code>true</code>.</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>>
- error_code & 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>
- <p><i>Remarks:</i> This operator shall not participate in overload resolution
- unless <code>is_error_code_enum<ErrorCodeEnum>::value</code> is <code>true</code>.</p>
- </blockquote>
- <p><code>void clear();</code></p>
- <blockquote>
- <p><i>postcondition:</i> <code>value() == 0 && category() ==
- system_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>const 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() != 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> 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 );
- // modifiers:
- void assign( int val, const error_category & cat );
- template<typename ErrorConditionEnum>
- error_condition & 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_ == &generic_category()</code>.</p>
- <p><i>Throws:</i> Nothing.</p>
- </blockquote>
- <pre>error_condition( int 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 e );</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(e)</code>.</p>
- <p><i>Throws:</i> Nothing.</p>
- <p><i>Remarks:</i> This constructor shall not participate in overload
- resolution unless <code>is_error_condition_enum<ErrorConditionEnum>::value</code>
- is <code>true</code>.</p>
- </blockquote>
- <h3><a name="Class-error_condition-modifiers">Class <code>error_condition</code>
- modifiers</a></h3>
- <pre>void assign( int 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>
- error_condition & operator=( ErrorConditionEnum e );</pre>
- <blockquote>
- <p><i>Postconditions:</i> <code>*this == make_error_condition( e )</code>.</p>
- <p><i>Returns:</i> <code>*this</code>.</p>
- <p><i>Throws:</i> Nothing.</p>
- <p><i>Remarks:</i> This operator shall not participate in overload resolution
- unless <code>is_error_condition_enum<ErrorConditionEnum>::value</code> is
- <code>true</code>.</p>
- </blockquote>
- <p><code>void clear();</code></p>
- <blockquote>
- <p><i>postcondition:</i> <code>value() == 0 && category() == generic_category()</code></p>
- </blockquote>
- <h3><a name="Class-error_condition-observers">Class <code>error_condition</code>
- observers</a></h3>
- <pre>int 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="throws-object"><code>throws</code> object</a></h2>
- <pre>extern error_code throws;</pre>
- <p>The predefined <code>error_code</code> object <code>throws</code> is supplied
- for use as a "throw on error" tag.</p>
- <h2><a name="Semantics-of-throws">Semantics of <code>throws</code></a> object</h2>
- <p>Functions that specify an argument in the form <code>error_code& ec=throws</code>,
- with appropriate namespace qualifiers, have the following error handling
- semantics:</p>
- <blockquote>
- <p><i>Postconditions:</i></p>
- <blockquote>
- <p>If <code>&ec != &throws</code> and an error occurred:</p>
- <ul>
- <li> <code>ec.value()</code> returns the implementation specific error
- number for the particular error that occurred.</li>
- <li><code>ec.category()</code> returns the <code>
- <a href="#Class-error_category">error_category</a></code> for <code>ec.value()</code>.</li>
- </ul>
- <p>if <code>&ec != &throws</code> and an error did not occur, <code>ec.clear()</code>.</p>
- </blockquote>
- <p><i>Throws:</i></p>
- <blockquote>
- <p>If an error occurs and <code>&ec == &throws</code>, throws an exception of type
- <code><a href="#Class-system_error">system_error</a></code> or of a type
- derived from <code><a href="#Class-system_error">system_error</a></code>. The
- exception's <code>code()</code> member function returns a reference to an
- <code>error_code</code> object with the behavior specified in <i>
- Postconditions</i>.</p>
- </blockquote>
- </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( errc::errc_t e );</pre>
- <blockquote>
- <p><i>Returns:</i> <code>error_code( e, generic_category())</code>.</p>
- </blockquote>
- <pre>error_condition make_error_condition( errc::errc_t e );</pre>
- <blockquote>
- <p><i>Returns:</i> <code>error_condition( static_cast<int>( e ), generic_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 errors that have an associated <code><a href="#Class-error_code">error_code</a></code>. Such errors typically originate from 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 char * what_arg );
- system_error( error_code ec, const std::string & what_arg );
- system_error( int ev, const error_category & ecat,
- const char * what_arg );
- system_error( int ev, const error_category & ecat,
- const std::string & what_arg );
- system_error( int 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 char * 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 ) == 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( int ev, const error_category & ecat,
- const char * 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 ) == 0</code></p>
- </blockquote>
- <pre>system_error( int 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( int 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>Revised
- <!--webbot bot="Timestamp" S-Type="EDITED" S-Format="%B %d, %Y" startspan -->June 29, 2010<!--webbot bot="Timestamp" endspan i-checksum="14432" --> </font>
- </p>
- <p>ゥ Copyright Beman Dawes, 2006, 2007, 2008</p>
- <p>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>
- </body>
- </html>