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| <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="#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>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( 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>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 ); |
| |
| // 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>© 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> |
