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POPassing in an Object to an abstract type's constructor in C++
 

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  1. POPassing in an Object to an abstract type's constructor in C++
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    <p>I'm trying to create CnD_Message_Handler of parent type i_MessageHandler. i_MessageHandler constructor takes a i_MessageFactory, another abstract class. CnD_Message_Factory inherits from i_MessageFactory. When I try to instantiate the CnD_Message_Handler, I get the following error: </p> <p><strong>error C2664: 'CnD_Message_Handler::CnD_Message_Handler' : cannot convert parameter 1 from 'CnD_Message_Factory' to 'const CnD_Message_Handler &amp;' Reason: cannot convert from 'CnD_Message_Factory' to 'const CnD_Message_Handler'</strong></p> <p>From examples online, I believe I'm passing msg_factory correctly. I'm also confused as the constructor requests i_MessageFactory(CnD_Message_Factory) instead of i_MessageHandler(CnD_Message_Handler)</p> <p>Thanks for any help in advance! </p> <p>CnD_Device (which instantiates CnD_Message_Factory and CnD_Message_Handler)</p> <pre><code>CnD_Device::CnD_Device(void) { CnD_Message_Factory msg_factory; //Inherited by i_MessageFactory CnD_Message_Handler msg_handler( msg_factory ); } </code></pre> <p>CnD_Message_Factory</p> <pre><code>#include "i_messagefactory.h" class CnD_Message_Factory : public i_MessageFactory { public: CnD_Message_Factory(void); ~CnD_Message_Factory(void); /** * Creates a message using the stream of data passed in. * @param id Id of the message to create. * @param stream Data stream to create the message from. * @return The created message (which must be returned to the factory by * calling the deleteMessage() method, or null if the factory could not * create a message. */ Message* createMessage(UInt32 id, const char* stream); /** * Returns a message to the factory for deleting/recycling. * @param msg The message being returned. */ void deleteMessage(Message&amp; msg); }; </code></pre> <p>CnD_Message_Handler</p> <pre><code>#include "i_messagehandler.h" class CnD_Message_Handler : public i_MessageHandler { public: CnD_Message_Handler::~CnD_Message_Handler(void); /** * Called by a i_MessageDriver object to process a message received. * @param msg Message to process. */ void CnD_Message_Handler::handleMessage (Message&amp; msg); /** * Called by a i_MessageDriver object when an error occurs with an * interface The exact type of errors are driver specific. * @param error The error that occurred. */ void CnD_Message_Handler::handleError (MessageEvent&amp; error); /** * Called by the i_MessageDriver object when an event occurs with an * interface. The exact type of events are driver specific. * @param event The event that occurred. */ void CnD_Message_Handler::handleEvent (MessageEvent&amp; event); }; </code></pre> <p>i_MessageHandler</p> <pre><code> class i_MessageFactory { public: /** * Destructor. */ virtual ~i_MessageFactory(void) { } /** * Creates a message using the stream of data passed in. * @param id Id of the message to create. * @param stream Data stream to create the message from. * @return The created message (which must be returned to the factory by * calling the deleteMessage() method, or null if the factory could not * create a message. */ virtual Message* createMessage(UInt32 id, const char* stream) = 0; /** * Returns a message to the factory for deleting/recycling. * @param msg The message being returned. */ virtual void deleteMessage(Message&amp; msg) = 0; protected: /** * Constructor. */ i_MessageFactory(void) { } }; </code></pre>
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    1. COFix your code formatting if you want any help.
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    2. COI'm sorry, what's wrong with my code formatting? Should I post all my code?
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    3. COIt might be helpful to you to try to create an example of your problem in a separate cpp -- outside your project. See if you can crystalize the problem to some basic code. Cause I've been playing around with different permutations in a sandbox project based on what you've given and can't get your error to happen.
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