如何对多个C++源文件中接口进行导出声明

// NumberType.cpp 
#include "NumberType.h"    // 引入头文件 
// NumberType是类名，Add是它的函数 
napi_value NumberType::Add(napi_env env, napi_callback_info info) { 
    // ... 业务功能实现代码 
}

#include "NumberType.h" 
#include "napi/native_api.h" 
// ... 
EXTERN_C_START 
static napi_value Init(napi_env env, napi_value exports) { 
    /* Associate the externally provided interface with the written method, for example, associate add with the Add 
     * method. 
    */ 
    napi_property_descriptor desc[] = { 
        {"add", nullptr, NumberType::Add, nullptr, nullptr, nullptr, napi_default, nullptr}}; 
    // napi_define_properties construct a return value that contains a list of methods that correspond. 
    napi_define_properties(env, exports, sizeof(desc) / sizeof(desc[0]), desc); 
    return exports; 
} 
EXTERN_C_END 
// ...

// index.d.ts  
export const add: (a: number, b: number) => number;