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| <html xmlns="http://www.w3.org/1999/xhtml"><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /><title>Adding Data to Exceptions</title><meta name="generator" content="DocBook XSL Stylesheets V1.73.2" /><meta name="keywords" content=" ISO C++ , library " /><link rel="start" href="../spine.html" title="The GNU C++ Library Documentation" /><link rel="up" href="bk01pt03ch07.html" title="Chapter 7. Exceptions" /><link rel="prev" href="bk01pt03ch07.html" title="Chapter 7. Exceptions" /><link rel="next" href="bk01pt03ch07s03.html" title="Cancellation" /></head><body><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="3" align="center">Adding Data to Exceptions</th></tr><tr><td width="20%" align="left"><a accesskey="p" href="bk01pt03ch07.html">Prev</a> </td><th width="60%" align="center">Chapter 7. Exceptions</th><td width="20%" align="right"> <a accesskey="n" href="bk01pt03ch07s03.html">Next</a></td></tr></table><hr /></div><div class="sect1" lang="en" xml:lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="manual.diagnostics.exceptions.data"></a>Adding Data to Exceptions</h2></div></div></div><p> |
| The standard exception classes carry with them a single string as |
| data (usually describing what went wrong or where the 'throw' took |
| place). It's good to remember that you can add your own data to |
| these exceptions when extending the hierarchy: |
| </p><pre class="programlisting"> |
| struct My_Exception : public std::runtime_error |
| { |
| public: |
| My_Exception (const string& whatarg) |
| : std::runtime_error(whatarg), e(errno), id(GetDataBaseID()) { } |
| int errno_at_time_of_throw() const { return e; } |
| DBID id_of_thing_that_threw() const { return id; } |
| protected: |
| int e; |
| DBID id; // some user-defined type |
| }; |
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