Compilation error : 'this' cannot be implicitly captured in this context

c++ scope this condition-variable
Ray picture Ray · Jul 26, 2016 · Viewed 17k times · Source

I am trying to add a condition_variable to handle threads, but get a compilation error at this line:

this->cv.wait(lk, []{return this->ready;});

Looks like the for the variable this->ready, the 'this' is not in the right scope.

In Java this can be handled with TestThread.this, is there anything in C++ doing the same?

void TestThread::Thread_Activity()
    {
        std::cout << "Thread started \n";
        // Wait until ThreadA() sends data
        {
            std::unique_lock<std::mutex> lk(m);
            this->cv.wait(lk, []{return ready;});
        }

        std::cout << "Thread is processing data\n";
        data += " after processing";
        // Send data back to ThreadA through the condition variable
        {
           // std::lock_guard<std::mutex> lk(m);
            processed = true;
           // std::cout << "Thread B signals data processing completed\n";
        }

    }

Answer

m.s. picture m.s. · Jul 26, 2016

You need to capture the this pointer:

this->cv.wait(lk, [this]{return ready;});

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