Method makeDefault

include/CL/opencl.hpp:2658–2694

! \brief Create the default context. * * This sets @c default_ and @c default_error_. It does not throw * @c cl::Error. */

    * @c cl::Error.
    */
    static void makeDefault() {
        /* Throwing an exception from a call_once invocation does not do
        * what we wish, so we catch it and save the error.
        */
#if defined(CL_HPP_ENABLE_EXCEPTIONS)
        try
#endif
        {
            // If default wasn't passed ,generate one
            // Otherwise set it
            cl_uint n = 0;

            cl_int err = ::clGetPlatformIDs(0, nullptr, &n);
            if (err != CL_SUCCESS) {
                default_error_ = err;
                return;
            }
            if (n == 0) {
                default_error_ = CL_INVALID_PLATFORM;
                return;
            }

            vector<cl_platform_id> ids(n);
            err = ::clGetPlatformIDs(n, ids.data(), nullptr);
            if (err != CL_SUCCESS) {
                default_error_ = err;
                return;
            }

            default_ = Platform(ids[0]);
        }
#if defined(CL_HPP_ENABLE_EXCEPTIONS)
        catch (cl::Error &e) {
            default_error_ = e.err();
        }
#endif
    }

    /*! \brief Create the default platform from a provided platform.
     *