Modern C++ API and lookup_datareader

Hi Nico,

In Modern C++, you should use the method find_datareader_by_name(). Let me provide you with a snippet:

// Create a subscriber
 dds::sub::Subscriber subscriber(participant);
 
// Create a DataReader with Qos setting its name
dds::sub::qos::DataReaderQos reader_qos = participant->default_datareader_qos();
reader_qos->subscription_name.name("MyReader");  
dds::sub::DataReader<test> reader(subscriber, topic, reader_qos); 

// Find the DataReader from within the subscriber, using the DataReader's name 
const std::string name("MyReader");
dds::sub::DataReader<test> found_reader =
        rti::sub::find_datareader_by_name<dds::sub::DataReader<test>>(subscriber, name);
 
if (found_reader != dds::core::null) { 
    std::cout << "Found DataReader's name is: " << found_reader->qos()->subscription_name.name().get() << std::endl; 
} else {
    return -1;
} 

The output of the cout line is: Found DataReader's name is: MyReader. There are more methods to find more entities. If you go to the Modern C++ API website and type "find", the autocompletion will show you the available methods.

Please, let me know if this helps.

-Fran

Hi.  How would this work if one is searching for the presence of a reader on another node?

I have publisher code that needs to wait for a subscriber before it publishes.  It can't count subscribers because other things out there might be subscribed, like recorders and the admin console.