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  PUBLIC "-//OASIS//DTD DITA Task//EN" "task.dtd">

<task id="GUID-895A685E-83E8-51A3-A823-3A0E07B1E609" xml:lang="en"><title>Exporting

the Implementation Factories </title><abstract><p>An implementation collection gathers one or more interface implementations

in a DLL. It provides necessary information to the plug-in framework to use

them. The collection must export a single function that provides an array.

This array maps the UID of each implementation it contains with a pointer

to its factory instantiation function (NewL() in our example). </p></abstract><prolog><metadata><keywords/></metadata></prolog><taskbody>

<steps id="GUID-B972BA4F-6146-59A7-AA8E-8ACC704F34FB">

<step id="GUID-E2BCAA54-9873-5AB5-93F8-6F1CE28D184D"><cmd/>

<info>Define a UID for each implementation. This UID maps to the instantiation

function of the implementation. Construct an array of UID's for all the implementations

in the collection. </info>

<stepxmp><codeblock id="GUID-F1292D30-2559-5F6C-ACD5-CEFD60F84EA7" xml:space="preserve">// Define the interface UIDs

const TImplementationProxy ImplementationTable[] = 

    {

    {{0x10009DC3}, CImplementationClassOne::NewL();},

    {{0x10009DC4}, CImplementationClassTwo::NewL();}

    };

    }</codeblock> </stepxmp>

</step>

<step id="GUID-D465B0AD-350A-597F-A0AB-D71F44F1CAEB"><cmd/>

<info>The signature of this exported function must be: </info>

<stepxmp><codeblock id="GUID-847AC15E-6714-5399-827C-2C04423A8CE7" xml:space="preserve">const TImplementationProxy* ImplementationGroupProxy(TInt&amp; aTableCount);</codeblock> </stepxmp>

</step>

<step id="GUID-43C85534-AD27-5F72-A57E-5271397C1C21"><cmd/>

<info>The exported function returns a pointer to an array of <xref href="GUID-A91AD391-D638-3FD4-93E3-B77B85767CCD.dita"><apiname>TImplementationProxy</apiname></xref> objects. </info>

</step>

<step id="GUID-D66DC4B4-3B8A-59CF-A74E-2FE499F5CA83"><cmd/>

<info>Each <codeph>TImplementationProxy</codeph> contains a UID and a function

pointer. </info>

<info> <codeph>aTableCount</codeph> should be set to the number of items in

the array. </info>

<stepxmp><codeblock id="GUID-2AAD649D-BC66-55B1-9EA1-9C30CF96BB4B" xml:space="preserve">EXPORT_C const TImplementationProxy* ImplementationGroupProxy(TInt&amp; aTableCount)

    {

    aTableCount = sizeof(ImplementationTable) / sizeof(TImplementationProxy);

    return ImplementationTable;

    }</codeblock> </stepxmp>

</step>

</steps>