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<concept xml:lang="en" id="GUID-38C37BA5-B972-5C8B-B8DE-B2FECF2A3C3C"><title>Single Phase Constructor</title><prolog><metadata><keywords/></metadata></prolog><conbody><p>Single phase constructor is to push a pointer to the clean-up stack, and then complete its construction. It uses the macro <xref href="GUID-8BB41BAD-5ED4-32E5-B4B4-312E472297CB.dita"><apiname>CONSTRUCTORS_MAY_LEAVE</apiname></xref> that is necessary to ensure whether the cleanup is correctly handled in the event that a constructor may leave beneath a call to new(ELeave). </p> <example><title>Characteristics of single phase constructor</title> <p>The following are the major characteristics of single phase constructor: </p> <ul><li id="GUID-2682874E-E2C1-5985-A1E5-0C802889575B"><p>The implementation of NewL becomes much simpler </p> </li> <li id="GUID-CDFDB865-4BCA-59E5-9E20-60591E04027B"><p>By using RAII classes in fields to manage owned resources, constructor exception-safety can be maintained </p> </li> <li id="GUID-765D89CC-8B72-5A11-8392-82861D056A30"><p>Cleanup stack technology </p> </li> </ul> </example> <section><title>Example</title> <p>The following code snippet implies the usage of single phase constructor using <xref href="GUID-8BB41BAD-5ED4-32E5-B4B4-312E472297CB.dita"><apiname>CONSTRUCTORS_MAY_LEAVE</apiname></xref> macro. </p> <codeblock id="GUID-7A76F800-7980-58A0-9DCA-95502E8D4F3E" xml:space="preserve">

        class CManagedUserSinglePhase : public CBase

            {

            public:

            CONSTRUCTORS_MAY_LEAVE

            static CManagedUserSinglePhase* NewL(CTicker* aTicker)

                {

                    return new(ELeave) CManagedUserSinglePhase(aTicker);

                }

            }