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"http://www.oasis-open.org/docbook/xml/4.5/docbookx.dtd"
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"http://www.oasis-open.org/docbook/xml/4.5/docbookx.dtd"
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[ ]>
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[ ]>
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ISO C++
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ISO C++
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library
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library
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</code></pre></td>
<td class="diff"><pre><code><title></code></pre></td>
</tr>
<tr class="diffcode">
<td class="diff"><pre><code> Diagnostics</code></pre></td>
<td class="diff"><pre><code> Diagnostics</code></pre></td>
</tr>
<tr class="diffcode">
<td class="diff"><pre><code> <indexterm><primary>Diagnostics</primary></indexterm></code></pre></td>
<td class="diff"><pre><code> <indexterm><primary>Diagnostics</primary></indexterm></code></pre></td>
</tr>
<tr class="diffcode">
<td class="diff"><pre><code>
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Exceptions
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Exceptions
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API Reference
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API Reference
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All exception objects are defined in one of the standard header
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All exception objects are defined in one of the standard header
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files: exception,
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files: exception,
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stdexcept, new, and
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stdexcept, new, and
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typeinfo.
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typeinfo.
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The base exception object is exception,
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The base exception object is exception,
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located in exception. This object has no
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located in exception. This object has no
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string member.
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string member.
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Derived from this are several classes that may have a
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Derived from this are several classes that may have a
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string member: a full hierarchy can be
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string member: a full hierarchy can be
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found in the source documentation.
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found in the source documentation.
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Full API details.
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Full API details.
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Adding Data to <classname>exception</classname>
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Adding Data to <classname>exception</classname>
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The standard exception classes carry with them a single string as
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The standard exception classes carry with them a single string as
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data (usually describing what went wrong or where the 'throw' took
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data (usually describing what went wrong or where the 'throw' took
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place). It's good to remember that you can add your own data to
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place). It's good to remember that you can add your own data to
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these exceptions when extending the hierarchy:
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these exceptions when extending the hierarchy:
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struct My_Exception : public std::runtime_error
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struct My_Exception : public std::runtime_error
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{
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{
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public:
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public:
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My_Exception (const string& whatarg)
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My_Exception (const string& whatarg)
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: std::runtime_error(whatarg), e(errno), id(GetDataBaseID()) { }
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: std::runtime_error(whatarg), e(errno), id(GetDataBaseID()) { }
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int errno_at_time_of_throw() const { return e; }
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int errno_at_time_of_throw() const { return e; }
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DBID id_of_thing_that_threw() const { return id; }
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DBID id_of_thing_that_threw() const { return id; }
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protected:
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protected:
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int e;
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int e;
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DBID id; // some user-defined type
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DBID id; // some user-defined type
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};
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};
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Concept Checking
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Concept Checking
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In 1999, SGI added concept checkers to their
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In 1999, SGI added concept checkers to their
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implementation of the STL: code which checked the template
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implementation of the STL: code which checked the template
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parameters of instantiated pieces of the STL, in order to insure
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parameters of instantiated pieces of the STL, in order to insure
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that the parameters being used met the requirements of the
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that the parameters being used met the requirements of the
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standard. For example, the Standard requires that types passed as
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standard. For example, the Standard requires that types passed as
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template parameters to vector be
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template parameters to vector be
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"Assignable" (which means what you think it means). The
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"Assignable" (which means what you think it means). The
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checking was done during compilation, and none of the code was
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checking was done during compilation, and none of the code was
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executed at runtime.
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executed at runtime.
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Unfortunately, the size of the compiler files grew significantly
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Unfortunately, the size of the compiler files grew significantly
|
as a result. The checking code itself was cumbersome. And bugs
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as a result. The checking code itself was cumbersome. And bugs
|
were found in it on more than one occasion.
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were found in it on more than one occasion.
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|
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The primary author of the checking code, Jeremy Siek, had already
|
The primary author of the checking code, Jeremy Siek, had already
|
started work on a replacement implementation. The new code has been
|
started work on a replacement implementation. The new code has been
|
formally reviewed and accepted into
|
formally reviewed and accepted into
|
the
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the
|
Boost libraries, and we are pleased to incorporate it into the
|
Boost libraries, and we are pleased to incorporate it into the
|
GNU C++ library.
|
GNU C++ library.
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The new version imposes a much smaller space overhead on the generated
|
The new version imposes a much smaller space overhead on the generated
|
object file. The checks are also cleaner and easier to read and
|
object file. The checks are also cleaner and easier to read and
|
understand.
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understand.
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They are off by default for all versions of GCC.
|
They are off by default for all versions of GCC.
|
They can be enabled at configure time with
|
They can be enabled at configure time with
|
--enable-concept-checks.
|
--enable-concept-checks.
|
You can enable them on a per-translation-unit basis with
|
You can enable them on a per-translation-unit basis with
|
-D_GLIBCXX_CONCEPT_CHECKS.
|
-D_GLIBCXX_CONCEPT_CHECKS.
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Please note that the upcoming C++ standard has first-class
|
Please note that the upcoming C++ standard has first-class
|
support for template parameter constraints based on concepts in the core
|
support for template parameter constraints based on concepts in the core
|
language. This will obviate the need for the library-simulated concept
|
language. This will obviate the need for the library-simulated concept
|
checking described above.
|
checking described above.
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