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POAdding specialized functionality to STL containers
 

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  1. POAdding specialized functionality to STL containers
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    <p>I have a very special scenario, and I'm trying to add functionality to "list"...</p> <pre><code>#include &lt;list&gt; template &lt;typename T&gt; class ShortList : public std::list&lt;T&gt; { private: unsigned short max_items; public: // Getter and setter methods unsigned short getMaxItems (void) { return this.max_items; } void setMaxItems (unsigned short max_items) { this.max_items = max_items; return; } // Work methods void insertItemSorted (T item) { std::list&lt;T&gt;::iterator i, e = this.short_list.end(); // Insertion sort O(n*max_items) for ( i = this.short_list.begin() ; i != e ; ++i ) { // Insert if smaller if ( item.getDiff() &lt; (*i).getDiff() ) { this.short_list.insert(i, item); // Restrict list size to max items if ( this.short_list.size() &gt; this.max_items ) { this.short_list.erase(this.short_list.end()); } } } return; } } </code></pre> <p>I can't understand what I'm doing wrong here. Here are my compile errors...</p> <pre class="lang-none prettyprint-override"><code>ShortList.cpp: In member function 'int ShortList&lt;T&gt;::insertItemSorted(T)': ShortList.cpp:21: error: expected `;' before 'i' ShortList.cpp:24: error: 'i' was not declared in this scope ShortList.cpp:24: error: 'e' was not declared in this scope ShortList.cpp: At global scope: ShortList.cpp:35: error: expected unqualified-id at end of input </code></pre> <p>I feel as though I'm following a C++ tutorial to the letter. Can anyone explain where I've gone wrong? I know it's poor form to extend the functionality of a STL container, but this a is purely a scholarly pursuit.</p>
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    1. USCody Gray
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    1. COIt's not just "poor form" to inherit from STL containers, it's a terrifically bad idea because they are not designed for it. For starters, many of them do not have virtual destructors.
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      1. USCody Gray
    2. COYou should implement a wrapper for std::list instead.
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    3. CO@CodyGray, does it mean that if any class doesn't have `virtual` function/destructor should never get publicly derived ? Apart from your comment, many a times I have come across this matter that STL containers should never get derived. I feel that, it's an unnecessary fear. If someone wants to extend them for functionality extension, there shouldn't be any problem
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      1. USiammilind
 

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