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POAre there cases where a "finally" construct would be useful in C++?
 

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  1. POAre there cases where a "finally" construct would be useful in C++?
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    <p>Bjarne Stroustrup writes in his <a href="http://www.research.att.com/~bs/bs_faq2.html#finally" rel="nofollow noreferrer">C++ Style and Technique FAQ</a>, emphasis mine:</p> <blockquote> <p>Because C++ supports an alternative that is <strong><em>almost always better</em></strong>: The "resource acquisition is initialization" technique (TC++PL3 section 14.4). The basic idea is to represent a resource by a local object, so that the local object's destructor will release the resource. That way, the programmer cannot forget to release the resource. For example:</p> <pre><code>class File_handle { FILE* p; public: File_handle(const char* n, const char* a) { p = fopen(n,a); if (p==0) throw Open_error(errno); } File_handle(FILE* pp) { p = pp; if (p==0) throw Open_error(errno); } ~File_handle() { fclose(p); } operator FILE*() { return p; } // ... }; void f(const char* fn) { File_handle f(fn,"rw"); // open fn for reading and writing // use file through f } </code></pre> <p>In a system, we need a "resource handle" class for each resource. However, we don't have to have an "finally" clause for each acquisition of a resource. In realistic systems, there are far more resource acquisitions than kinds of resources, so the "resource acquisition is initialization" technique leads to less code than use of a "finally" construct.</p> </blockquote> <p>Note that Bjarne writes "almost always better" and not "always better". Now for my question: What situation would a <code>finally</code> construct be better than using the alternative construct (RAII) in C++?</p>
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      1. POAre there cases where a "finally" construct would be useful in C++?
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    1. COYou're asking two different questions. The title asks why there is no finally, and the actual post asks for examples of cases where finally would be better than RAII. I suggest you edit one of them, so they actually match up. It's confusing for people who stumble upon this post in a search.
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