[fpc-pascal] How do I pass a call back Class and its method to an external library *.so file writting in C++

[Dennis]

Dear All,

I am given an API linux library *.so file written in C++.
It was expected to be consume by a program written in C++.
However, I would like to write such a program in Free Pascal.

The given header file is:
#ifndef ApiProxyWrapperReplyH
#define ApiProxyWrapperReplyH
//---------------------------------------------------------------------------
#include <stdio.h>
#include "SPApiProxyDataType.h"
class ApiProxyWrapperReply {

public:
     ApiProxyWrapperReply(void){};
     ~ApiProxyWrapperReply(void){};
     virtual void OnLoginReply(char *user_id, long ret_code,char 
*ret_msg) = 0;
     virtual void OnConnectedReply(long host_type,long con_status) = 0;
     virtual void OnApiOrderRequestFailed(tinyint action, const 
SPApiOrder *order, long err_code, char *err_msg) = 0;
     virtual void OnApiOrderReport(long rec_no, const SPApiOrder *order) 
= 0;
     virtual void OnApiOrderBeforeSendReport(const SPApiOrder *order) = 0;
     virtual void OnAccountLoginReply(char *accNo, long ret_code, char* 
ret_msg) = 0;
     virtual void OnAccountLogoutReply(char *accNo, long ret_code, char* 
ret_msg) = 0;
     virtual void OnAccountInfoPush(const SPApiAccInfo *acc_info) = 0;
     virtual void OnAccountPositionPush(const SPApiPos *pos) = 0;
     virtual void OnUpdatedAccountPositionPush(const SPApiPos *pos) = 0;
     virtual void OnUpdatedAccountBalancePush(const SPApiAccBal 
*acc_bal) = 0;
     virtual void OnApiTradeReport(long rec_no, const SPApiTrade *trade) 
= 0;
     virtual void OnApiPriceUpdate(const SPApiPrice *price) = 0;
     virtual void OnApiTickerUpdate(const SPApiTicker *ticker) = 0;
     virtual void OnPswChangeReply(long ret_code, char *ret_msg) = 0;
     virtual void OnProductListByCodeReply(long req_id, char *inst_code, 
bool is_ready, char *ret_msg) = 0;
     virtual void OnInstrumentListReply(long req_id, bool is_ready, char 
*ret_msg) = 0;
     virtual void OnBusinessDateReply(long business_date) = 0;
     virtual void OnApiMMOrderBeforeSendReport(SPApiMMOrder *mm_order) = 0;
     virtual void OnApiMMOrderRequestFailed(SPApiMMOrder *mm_order, long 
err_code, char *err_msg) = 0;
     virtual void OnApiQuoteRequestReceived(char *product_code, char 
buy_sell, long qty) = 0;
     virtual void OnApiAccountControlReply(long ret_code, char *ret_msg) 
= 0;
     virtual void OnApiLoadTradeReadyPush(long rec_no, const SPApiTrade 
*trade) = 0;
};

#endif

I am expected to create and pass an instance of such class 
ApiProxyWrapperReply in my calling program
  via a function
void SPAPI_RegisterApiProxyWrapperReply(ApiProxyWrapperReply* 
apiProxyWrapperReply);

and the external library will then call the various methods of 
ApiProxyWrapperReply  as 'call-back' functions when needed.

I consulted co-pilot but it failed to teach me how to do so in a Free 
Pascal program calling such an external library.

Please kindly help.

Dennis Poon