2000-04-22 04:33:34 +08:00
|
|
|
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0//EN">
|
|
|
|
|
<HTML>
|
|
|
|
|
<HEAD>
|
|
|
|
|
<META HTTP-EQUIV="Content-Type" CONTENT="text/html; charset=iso-8859-1">
|
2000-07-12 05:45:08 +08:00
|
|
|
<META NAME="AUTHOR" CONTENT="pme@sources.redhat.com (Phil Edwards)">
|
2000-04-22 04:33:34 +08:00
|
|
|
<META NAME="KEYWORDS" CONTENT="HOWTO, libstdc++, egcs, g++, libg++, STL">
|
|
|
|
|
<META NAME="DESCRIPTION" CONTENT="HOWTO for the libstdc++ chapter 19.">
|
|
|
|
|
<META NAME="GENERATOR" CONTENT="vi and eight fingers">
|
|
|
|
|
<TITLE>libstdc++-v3 HOWTO: Chapter 19</TITLE>
|
2000-07-12 05:45:08 +08:00
|
|
|
<LINK REL="home" HREF="http://sources.redhat.com/libstdc++/docs/19_diagnostics/">
|
2000-04-22 04:33:34 +08:00
|
|
|
<LINK REL=StyleSheet HREF="../lib3styles.css">
|
2000-07-12 05:45:08 +08:00
|
|
|
<!-- $Id: howto.html,v 1.2 2000/07/07 21:13:28 pme Exp $ -->
|
2000-04-22 04:33:34 +08:00
|
|
|
</HEAD>
|
|
|
|
|
<BODY>
|
|
|
|
|
|
|
|
|
|
<H1 CLASS="centered"><A NAME="top">Chapter 19: Diagnostics</A></H1>
|
|
|
|
|
|
|
|
|
|
<P>Chapter 19 deals with program diagnostics, such as exceptions
|
2000-07-08 05:13:28 +08:00
|
|
|
and assertions. You know, all the things we wish weren't even
|
|
|
|
|
necessary at all.
|
2000-04-22 04:33:34 +08:00
|
|
|
</P>
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
<!-- ####################################################### -->
|
|
|
|
|
<HR>
|
|
|
|
|
<H1>Contents</H1>
|
|
|
|
|
<UL>
|
|
|
|
|
<LI><A HREF="#1">Adding data to exceptions</A>
|
|
|
|
|
<LI><A HREF="#2">Exception class hierarchy diagram</A>
|
2000-07-08 05:13:28 +08:00
|
|
|
<LI><A HREF="#3">Concept checkers</A>
|
2000-04-22 04:33:34 +08:00
|
|
|
</UL>
|
|
|
|
|
|
|
|
|
|
<HR>
|
|
|
|
|
|
|
|
|
|
<!-- ####################################################### -->
|
|
|
|
|
|
|
|
|
|
<H2><A NAME="1">Adding data to exceptions</A></H2>
|
|
|
|
|
<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 heirarchy:
|
|
|
|
|
</P>
|
|
|
|
|
<PRE>
|
|
|
|
|
using std::runtime_error;
|
|
|
|
|
struct My_Exception : public runtime_error
|
|
|
|
|
{
|
|
|
|
|
public:
|
|
|
|
|
My_Exception (const string& whatarg)
|
|
|
|
|
: 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
|
|
|
|
|
};
|
|
|
|
|
</PRE>
|
|
|
|
|
<P>Return <A HREF="#top">to top of page</A> or
|
|
|
|
|
<A HREF="../faq/index.html">to the FAQ</A>.
|
|
|
|
|
</P>
|
|
|
|
|
|
|
|
|
|
<HR>
|
|
|
|
|
<H2><A NAME="2">Exception class hierarchy diagram</A></H2>
|
|
|
|
|
<P>The <A HREF="exceptions_hiearchy.pdf">diagram</A> is in PDF, or
|
|
|
|
|
at least it will be once it gets finished.
|
|
|
|
|
</P>
|
|
|
|
|
<P>Return <A HREF="#top">to top of page</A> or
|
|
|
|
|
<A HREF="../faq/index.html">to the FAQ</A>.
|
|
|
|
|
</P>
|
|
|
|
|
|
2000-07-08 05:13:28 +08:00
|
|
|
<HR>
|
|
|
|
|
<H2><A NAME="3">Concept checkers</A></H2>
|
|
|
|
|
<P>As part of their 3.3 release, SGI added some nifty macros which
|
|
|
|
|
perform assertions on type properties. For example, the Standard
|
|
|
|
|
requires that types passed as template parameters to <TT>vector</TT>
|
|
|
|
|
be "Assignable" (which means what you think it means).
|
|
|
|
|
</P>
|
|
|
|
|
<P>The concept checkers allow the source code for <TT>vector</TT> to
|
|
|
|
|
declare
|
|
|
|
|
<PRE>
|
|
|
|
|
__STL_CLASS_REQUIRES(_Tp, _Assignable);
|
|
|
|
|
</PRE>inside the template. <TT>_Tp</TT> is the element type of the
|
|
|
|
|
vector, and <TT>_Assignable</TT> is the concept to be checked (it is
|
|
|
|
|
defined in some back-end header files). When you instantiate
|
|
|
|
|
<TT>vector<MyType></TT>, compile-time checking can be done on
|
|
|
|
|
whether MyType meets the requirements for vectors.
|
|
|
|
|
</P>
|
|
|
|
|
<P>This is an extension to the library. This documentation needs updating.</P>
|
|
|
|
|
<P>Return <A HREF="#top">to top of page</A> or
|
|
|
|
|
<A HREF="../faq/index.html">to the FAQ</A>.
|
|
|
|
|
</P>
|
|
|
|
|
|
|
|
|
|
|
2000-04-22 04:33:34 +08:00
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
<!-- ####################################################### -->
|
|
|
|
|
|
|
|
|
|
<HR>
|
|
|
|
|
<P CLASS="fineprint"><EM>
|
|
|
|
|
Comments and suggestions are welcome, and may be sent to
|
2000-07-12 05:45:08 +08:00
|
|
|
<A HREF="mailto:pme@sources.redhat.com">Phil Edwards</A> or
|
2000-04-22 04:33:34 +08:00
|
|
|
<A HREF="mailto:gdr@egcs.cygnus.com">Gabriel Dos Reis</A>.
|
2000-07-12 05:45:08 +08:00
|
|
|
<BR> $Id: howto.html,v 1.2 2000/07/07 21:13:28 pme Exp $
|
2000-04-22 04:33:34 +08:00
|
|
|
</EM></P>
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
</BODY>
|
|
|
|
|
</HTML>
|
