Author: wyoung
Date: Thu Feb 7 05:14:01 2008
New Revision: 2165
URL: http://svn.gna.org/viewcvs/mysqlpp?rev=2165&view=rev
Log:
Replaced the assert() on failing to look up MySQL C API type information
from C++ type info in mysql_type_info::types[] with a new non-optional
exception, TypeLookupFailed.
Modified:
trunk/doc/userman/breakages.dbx
trunk/doc/userman/tutorial.dbx
trunk/lib/exceptions.h
trunk/lib/type_info.h
Modified: trunk/doc/userman/breakages.dbx
URL:
http://svn.gna.org/viewcvs/mysqlpp/trunk/doc/userman/breakages.dbx?rev=2165&r1=2164&r2=2165&view=diff
==============================================================================
--- trunk/doc/userman/breakages.dbx (original)
+++ trunk/doc/userman/breakages.dbx Thu Feb 7 05:14:01 2008
@@ -841,25 +841,30 @@
this affects you, see <xref linkend="ssqls-vc2003"/> for
suggestions on ways to cope.</para>
- <para>If you aren’t using the <type>sql_*</type> data
- types in your SSQLSes there’s a chance your program may
- crash when using that SSQLS. <footnote><para>These typedefs
+ <para>If you are using types other than MySQL++’s
+ <type>sql_*</type> ones <footnote><para>These typedefs
have been available since MySQL++ v2.1.</para></footnote>
- This version of MySQL++ is stricter about mapping SQL to C++
- type information, and vice versa. You know you’ve
- run across this if you get a run-time assertion about
- <computeroutput>it != map_.end()</computeroutput> in
- <filename>lib/type_info.h</filename>, on or around line
- 121. It means MySQL++ fell off the end of its internal SQL
- to C++ data type map<footnote><para>This map is built from
+ in your SSQLSes, code that previously worked may now see
+ <classname>TypeLookupFailed</classname> exceptions. (This
+ can be thrown even if exceptions are otherwise disabled in
+ MySQL++.) This version of MySQL++ is stricter about mapping
+ SQL to C++ type information, and vice versa. If the library
+ can’t find a suitable mapping from one type system
+ to the other, it throws this exception, because its only
+ other option would be to crash or raise an assertion. This
+ typically happens when building SQL queries, so you can
+ probably handle it the same way as if the subsequent
+ query excecution failed. If you’re catching the
+ generic <classname>mysqlpp::Exception</classname>, your
+ error handling code might not need to change. If you see
+ this exception, it does mean you need to look into your
+ use of data types, though. The table that controls this is
<varname>mysql_type_info::types</varname>, defined at the top
- of <filename>lib/type_info.cpp</filename>.</para></footnote>
- when looking for appropriate conversion information.
- Every data type in <filename>lib/sql_types.h</filename>
- has a corresponding record in the type map, so if you stick
- to those types, you’ll be fine. It's also okay to
- use types your C++ compiler can convert directly to these
- predefined types.</para>
+ of <filename>lib/type_info.cpp</filename>. Every data type in
+ <filename>lib/sql_types.h</filename> has a corresponding record
+ in this table, so if you stick to those types, you’ll
+ be fine. It’s also okay to use types your C++ compiler
+ can convert directly to these predefined types.</para>
</sect4>
Modified: trunk/doc/userman/tutorial.dbx
URL:
http://svn.gna.org/viewcvs/mysqlpp/trunk/doc/userman/tutorial.dbx?rev=2165&r1=2164&r2=2165&view=diff
==============================================================================
--- trunk/doc/userman/tutorial.dbx (original)
+++ trunk/doc/userman/tutorial.dbx Thu Feb 7 05:14:01 2008
@@ -232,48 +232,48 @@
<sect2 id="exceptions" xreflabel="exceptions">
<title>Exceptions</title>
- <para>By default, MySQL++ uses exceptions to signal errors. Most of
- the examples have a full set of exception handlers. This is worthy
- of emulation.</para>
-
- <para>All of MySQL++’s custom exceptions derive from a common
- base class, <ulink type="classref" url="Exception"/>. That in turn
- derives from Standard C++’s
- <classname>std::exception</classname> class. Since the library can
- indirectly cause exceptions to come from the Standard C++ Library,
- it’s possible to catch all exceptions from MySQL++ by just
- catching <classname>std::exception</classname>. However, it’s
- better to have individual catch blocks for each of the concrete
- exception types that you expect, and add a handler for either
- <classname>Exception</classname> or
- <classname>std::exception</classname> to act as a
+ <para>By default, MySQL++ uses exceptions to signal errors. Most
+ of the examples have a full set of exception handlers. This is
+ worthy of emulation.</para>
+
+ <para>All of MySQL++’s custom exceptions
+ derive from a common base class, <ulink type="classref"
+ url="Exception"/>. That in turn derives from Standard C++’s
+ <classname>std::exception</classname> class. Since the library
+ can indirectly cause exceptions to come from the Standard
+ C++ Library, it’s possible to catch all exceptions from
+ MySQL++ by just catching <classname>std::exception</classname>.
+ However, it’s better to have individual catch blocks
+ for each of the concrete exception types that you expect, and
+ add a handler for either <classname>Exception</classname>
+ or <classname>std::exception</classname> to act as a
“catch-all” for unexpected exceptions.</para>
- <para>Some of these exceptions are optional. When exceptions are
- disabled on a MySQL++ object, it signals errors in some other way,
- typically by returning an error code or setting an error flag.
- Classes that support this feature derive from <ulink type="classref"
- url="OptionalExceptions"/>. Moreover, when such an object creates
- another object that also derives from this interface, it passes on
- its exception flag. Since everything flows from the <ulink
- type="classref" url="Connection"/> object, disabling exceptions on
- it at the start of the program disables all optional exceptions. You
- can see this technique at work in the
- <filename>simple[1-3]</filename> examples, which keeps them, well,
- simple.</para>
-
- <para>Real-world code typically can’t afford to lose out on
- the additional information and control offered by exceptions. But at
- the same time, it is still sometimes useful to disable exceptions
- temporarily. To do this, put the section of code that you want to
- not throw exceptions inside a block, and create a <ulink
- type="classref" url="NoExceptions"/> object at the top of that
- block. When created, it saves the exception flag of the
- <classname>OptionalExceptions</classname> derivative you pass to it,
- and then disables exceptions on it. When the
- <classname>NoExceptions</classname> object goes out of scope at the
- end of the block, it restores the exceptions flag to its previous
- state:</para>
+ <para>Most of these exceptions are optional. When exceptions
+ are disabled on a MySQL++ object, it signals errors in some
+ other way, typically by returning an error code or setting
+ an error flag. Classes that support this feature derive from
+ <ulink type="classref" url="OptionalExceptions"/>. Moreover,
+ when such an object creates another object that also derives from
+ this interface, it passes on its exception flag. Since everything
+ flows from the <ulink type="classref" url="Connection"/> object,
+ disabling exceptions on it at the start of the program disables
+ all optional exceptions. You can see this technique at work in
+ the <filename>simple[1-3]</filename> examples, which keeps them,
+ well, simple.</para>
+
+ <para>Real-world code typically can’t afford to lose
+ out on the additional information and control offered by
+ exceptions. But at the same time, it is still sometimes useful
+ to disable exceptions temporarily. To do this, put the section
+ of code that you want to not throw exceptions inside a block,
+ and create a <ulink type="classref" url="NoExceptions"/> object
+ at the top of that block. When created, it saves the exception
+ flag of the <classname>OptionalExceptions</classname> derivative
+ you pass to it, and then disables exceptions on it. When the
+ <classname>NoExceptions</classname> object goes out of scope
+ at the end of the block, it restores the exceptions flag to its
+ previous state:</para>
<programlisting>mysqlpp::Connection con(...); // exceptions enabled
@@ -290,14 +290,14 @@
passing a copy; the two objects’ flags operate independently.
There’s no way to globally enable or disable this flag on
existing objects in a single call. If you’re using the
- <classname>NoExceptions</classname> feature and you’re still
- seeing optional exceptions thrown, you disabled exceptions on the
- wrong object. The exception thrower could be unrelated to the object
- you disabled exceptions on, it could be its parent, or it could be a
- child created before you disabled optional exceptions.</para>
-
- <para>Some of the exceptions MySQL++ can throw are not
- optional:</para>
+ <classname>NoExceptions</classname> feature and you’re
+ still seeing optional exceptions thrown, you disabled exceptions
+ on the wrong object. The exception thrower could be unrelated to
+ the object you disabled exceptions on, it could be its parent,
+ or it could be a child created before you disabled optional
+ exceptions.</para>
+
+ <para>MySQL++ throws some exceptions unconditionally:</para>
<itemizedlist>
<listitem><para>The largest set of non-optional exceptions are
@@ -322,6 +322,13 @@
enough parameters when instantiating the template,
<classname>Query</classname> will throw a <ulink type="classref"
url="BadParamCount"/> exception.</para></listitem>
+
+ <listitem><para>If you use a C++ data type in a query
+ that MySQL++ doesn’t know to convert to SQL, MySQL++
+ will throw a <ulink type="classref" url="TypeLookupFailed"/>
+ exception. It typically happens with <xref linkend="ssqls"/>,
+ especially when using data types other than the ones defined
+ in <filename>lib/sql_types.h</filename>.</para></listitem>
</itemizedlist>
<para>It’s educational to modify the examples to force
@@ -365,7 +372,7 @@
<programlisting>
SELECT * FROM stock WHERE item = 'Frank's Brand Hotdog Buns' </programlisting>
- <para>That's not valid SQL syntax. The correct syntax is:</para>
+ <para>That’s not valid SQL syntax. The correct syntax is:</para>
<programlisting>
SELECT * FROM stock WHERE item = 'Frank''s Brand Hotdog Buns' </programlisting>
Modified: trunk/lib/exceptions.h
URL:
http://svn.gna.org/viewcvs/mysqlpp/trunk/lib/exceptions.h?rev=2165&r1=2164&r2=2165&view=diff
==============================================================================
--- trunk/lib/exceptions.h (original)
+++ trunk/lib/exceptions.h Thu Feb 7 05:14:01 2008
@@ -411,6 +411,28 @@
};
+/// \brief Thrown from the C++ to SQL data type conversion routine when
+/// it can't figure out how to map the type.
+///
+/// This exception is not optional. The only alternatives when this
+/// happens are equally drastic: basically, either iterate past the
+/// end of an array (crashing the program) or call assert() to crash
+/// the program nicely. At least this way you have some control over
+/// how your program ends. You can even ignore the error and keep on
+/// going: this typically happens when building a SQL query, so you can
+/// handle it just the same as if the subsequent query execution failed.
+
+class MYSQLPP_EXPORT TypeLookupFailed : public Exception
+{
+public:
+ /// \brief Create exception object
+ explicit TypeLookupFailed(const std::string& w) :
+ Exception(w)
+ {
+ }
+};
+
+
} // end namespace mysqlpp
#endif // !defined(MYSQLPP_EXCEPTIONS_H)
Modified: trunk/lib/type_info.h
URL:
http://svn.gna.org/viewcvs/mysqlpp/trunk/lib/type_info.h?rev=2165&r1=2164&r2=2165&view=diff
==============================================================================
--- trunk/lib/type_info.h (original)
+++ trunk/lib/type_info.h Thu Feb 7 05:14:01 2008
@@ -6,7 +6,7 @@
/***********************************************************************
Copyright (c) 1998 by Kevin Atkinson, (c) 1999-2001 by MySQL AB, and
- (c) 2004-2007 by Educational Technology Resources, Inc. Others may
+ (c) 2004-2008 by Educational Technology Resources, Inc. Others may
also hold copyrights on code in this file. See the CREDITS file in
the top directory of the distribution for details.
@@ -28,15 +28,16 @@
USA
***********************************************************************/
-#ifndef MYSQLPP_TYPE_INFO_H
+#if !defined(MYSQLPP_TYPE_INFO_H)
#define MYSQLPP_TYPE_INFO_H
#include "common.h"
+#include "exceptions.h"
+
#include <map>
+#include <sstream>
#include <typeinfo>
-
-#include <assert.h>
namespace mysqlpp {
@@ -118,8 +119,14 @@
const std::type_info& ti) const
{
map_type::const_iterator it = map_.find(&ti);
- assert(it != map_.end());
- return it->second;
+ if (it != map_.end()) {
+ return it->second;
+ }
+ else {
+ std::ostringstream outs;
+ outs << "Failed to find MySQL C API type ID for " <<
ti.name();
+ throw TypeLookupFailed(outs.str());
+ }
}
map_type map_;
@@ -336,5 +343,5 @@
} // end
namespace mysqlpp
-#endif
-
+#endif // !defined(MYSQLPP_TYPE_INFO_H)
+
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