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POMemory Management with Command Pattern
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17283737
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2013-06-24T19:42:19.650
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2013-06-24T20:56:38.547
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2013-06-24T20:50:32.927
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 So, I've got the following Command Pattern implementation, which is contained within a <code>std::map<CString, IWrite*> commandMap</code>: <pre class="lang-cpp prettyprint-override"><code>class IWrite { protected: CStdioFile* fileWriter; public: IWrite(CStdioFile* _fileWriter) : fileWriter(_fileWriter) { } virtual ~IWrite() { } virtual BOOL exec() = 0; }; </code></pre> <pre class="lang-cpp prettyprint-override"><code>class FloatWrite : public IWrite { private: float input; public: FloatWrite(CStdioFile* _fileWriter, float _input) : IWrite(_fileWriter), input(_input) { } BOOL exec() { CString fieldvalue; fieldvalue.Format("%f", input); fileWriter->WriteString(fieldvalue); return TRUE; } }; </code></pre> The issue I'm having is that my static analysis tool complains that <code>fileWriter</code> is not freed or zeroed in the destructor of <code>IWrite</code>. However, by adding a <code>delete fileWriter</code> in the destructor, I get a memory access error when I delete the Command Pattern object in the map before calling <code>std::map.clear()</code> as below: <pre class="lang-cpp prettyprint-override"><code>// free map memory for ( std::map<CString, IWrite*>::iterator mapItr = commandMap.begin(); mapItr != commandMap.end(); ++mapItr) { delete mapItr->second; } commandMap.clear(); </code></pre> Am I approaching memory management incorrectly here? I have not done much work with STL maps, so I'm not familiar with an idiomatic approach. EDIT: How I add elements to the map: <pre class="lang-cpp prettyprint-override"><code>void FooClass::initCommandMap(const MSG_DATA_STRUCT * msgdata) { // Write a float, foo commandMap[_T("foo")] = new FloatWrite(&fileWriter, msgdata->foo); // Write an unsigned int, bar commandMap[_T("bar")] = new UIntWrite(&fileWriter, msgdata->bar); // etc... } </code></pre> This is called each time the user chooses to write out the data, so the <code>fileWriter</code> object used by the various <code>exec()</code>'s is current with the file selected by the user. Note that <code>CStdioFile fileWriter</code> is a member variable of <code>FooClass</code>.
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<c++><memory-management><command-pattern>
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Memory Management with Command Pattern
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1. USCJ McAllister
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