Put method into a buffer in C++

Question

I have created this method to put some data in a buffer:

template <typename T>
void locked_buffer<T>::put(const T & x, bool last) noexcept
{
  using namespace std;
  unique_lock<mutex> l{mut_};
  not_full_.wait(l, [this] { return !do_full(); });
  buf_[next_write_] = item{last,x};
  next_write_ = next_position(next_write_);
  l.unlock();
  not_empty_.notify_one();
}

But, trying to put data which consists in a return of a function:

int size_b;
locked_buffer<long buf1{size_b}>;
buf1.put(image, true); //image is the return of the function

I've got problems with the boolean variable bool lastbecause I've got compilation errors.

Thanks.

Edit: The error that I obtained is the following one:

error: no matching function for call to 'locked_buffer<long int>::put(std::vector<std::vector<unsigned char>>&, bool)'

Provide a [MCVE] including the verbatim error messages please. — πάντα ῥεῖ, Dec 09 '16 at 13:41
ok... so is it locked_buffer or locked_buffer buf1{size_b}? I dont even know if the first option is even valid code to be honest. But regardless your compiler error says you are using 2 different data types for your template class, you are creating the class to expect a long int type for T and then you are passing a different type to the method, the type to the method needs to be the same type that is used to create your object. — AresCaelum, Dec 09 '16 at 13:59

score 2 · Accepted Answer · answered Dec 09 '16 at 14:07

error: no matching function for call to locked_buffer<long int>::put(std::vector<std::vector<unsigned char>>&, bool)

Tells you everything you need to know:

Your locked_buffer object is templated to type: long int
Your 1^st argument is of type: vector<vector<unsigned char>>

Now we know that these 2 types must be the same from your function definition:

template <typename T>
void locked_buffer<T>::put(const T & x, bool last) noexcept

The compiler's error is correct. You'll need to either use a matching locked_buffer object or create a new function:

template <typename T, typename R>
void locked_buffer<T>::put(const R& x, bool last) noexcept

Put method into a buffer in C++

1 Answers1