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POMaking a non-object resource RAII-compliant
 

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  1. POMaking a non-object resource RAII-compliant
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    <p>in my code I use <code>HANDLE</code>s from <code>windows.h</code>. They are used like</p> <pre><code>HANDLE h; if (!openHandleToSomething(arg1, arg2, &amp;h)) { throw std::exception("openHandleToSomething error"); } /* Use the handle in other functions which can throw as well */ if (!CloseHandle(h)) { throw std::exception("closeHandle error"); } </code></pre> <p>As you see, you have to insert this <code>CloseHandle</code> to every exception which can happen in the middle of acquiration and release. Therefore, it's likely you forget one (or there is a fancy SEH exception which you didn't know about) and voilà, you have your memory leak.</p> <p>Recently, I've read about RAII which should remove the headaches from such cases and should call this <code>CloseHandle</code> automatically. I've also seen that there is something like <code>std::auto_ptr&lt;someType&gt;</code> in C++ which solves the problem for resources which were allocated with <code>new</code>.</p> <p>However, since I don't use <code>new</code> and since <code>HANDLE</code> is just <code>typedef</code>ed to be a <code>void *</code>, I wonder how I should use the <code>std::auto_ptr&lt;someType&gt;</code>. Somehow, it should be possible to give it a custom deleter function (<code>if (!CloseHandle(h)) { throw std::exception("closeHandle error"); }</code>). Creating a class would be another method since the destructor gets called any time an instance of it gets out of scope. However, it's just overkill to have a class for every simple thing.</p> <p>How can I fix these accidential memory leaks?</p> <p>Note that I would prefer solutions which are in pure C++ with no libraries and big dependencies except if they are really small and used in most of the environments anyways.</p>
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