The Modern C++ Challenge

21. System handle wrapper

System handles are a form of reference to system resources. Because all operating systems were at least initially written in C, creating and releasing the handles is done through dedicated system functions. This increases the risk of leaking resources because of erroneous disposal, such as in the case of an exception. In the following snippet, specific to Windows, you can see a function where a file is opened, read from, and eventually closed. However, this has a couple of problems: in one case, the developer forgot to close the handle before leaving the function; in another case, a function that throws is called before the handle is properly closed, without the exception being caught. However, since the function ...