Symbian3/SDK/Source/GUID-FC24C65C-0DCB-5E07-9A68-9001D34664DD.dita
author Dominic Pinkman <dominic.pinkman@nokia.com>
Tue, 20 Jul 2010 12:00:49 +0100
changeset 13 48780e181b38
parent 0 89d6a7a84779
permissions -rw-r--r--
Week 28 contribution of SDK documentation content. See release notes for details. Fixes bugs Bug 1897 and Bug 1522.

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<concept xml:lang="en" id="GUID-FC24C65C-0DCB-5E07-9A68-9001D34664DD"><title>OR_LEAVE MACRO</title><prolog><metadata><keywords/></metadata></prolog><conbody><p>The <xref href="GUID-7EB97E3A-90F5-3536-B7AC-F6F55023E2F3.dita"><apiname>OR_LEAVE</apiname></xref> macro is a convenient macro that allows the application developer to de-emphasize auxiliary error checking code in most cases. It is a postfix macro which implements <xref href="GUID-C197C9A7-EA05-3F24-9854-542E984C612D.dita#GUID-C197C9A7-EA05-3F24-9854-542E984C612D/GUID-80E99D34-F4A1-36EA-AD64-E14ACAEC99B0"><apiname>User::LeaveIfError</apiname></xref> on an integer return type. This means that there is less focus on the error handling code and makes the code easier to read. </p> <section><title>Need for OR_Leave Macro</title> <p>Motive behind using a <xref href="GUID-7EB97E3A-90F5-3536-B7AC-F6F55023E2F3.dita"><apiname>OR_LEAVE</apiname></xref> macro is that it should not return an integer value. It is intended for use as a postfix macro at the end of a statement. If OR_LEAVE was to return an integer value, it would encourage its use in the middle of expressions negating its intended purpose which is to reduce the focus on error checking code. </p> </section> <example><title>Defining OR_Leave Macro</title> <p>The OR_LEAVE macro is defined as a postfix operator as shown below: </p> <codeblock id="GUID-DDB19E73-7D96-5D06-8EF9-AEC1248E8644" xml:space="preserve">
        #define OR_LEAVE || ELeave
        inline void operator||(TInt aStatus, TLeave /*aTag*/)
            {
            User::LeaveIfError(aStatus);
            }
</codeblock> </example> <section><title>See Also</title> <p><xref href="GUID-B007634D-4D55-528A-8B85-6120C633AC8B.dita">EUser High Level Library Overview</xref>  </p> <p><xref href="GUID-D33EB877-CCCB-527B-8AFC-4A8385C55E78.dita">EUser High Level Library Tutorials</xref>  </p> </section> </conbody></concept>