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POAccess C++ class member object, but do not allow to override it
 

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  1. POAccess C++ class member object, but do not allow to override it
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    <p>I'm learning C++ and i just have a small problem. I have a class which contains a <code>vector&lt;int&gt;</code>. From outside this <code>vector&lt;int&gt;</code> should be accessable, so it should be possible to add/remove/get its elements.</p> <p>It should not be possible to override the object with a new instance. Here is such an example class (it's minimalized):</p> <pre><code>class MyClass { public: vector&lt;int&gt;&amp; vec() { return _vec; } private: vector&lt;int&gt; _vec; }; </code></pre> <p>E.g. the following code works:</p> <pre><code>MyClass x; x.vec().push_back(0); x.vec().push_back(7); x.vec().push_back(9); cout &lt;&lt; c.vec().size() &lt;&lt; endl; </code></pre> <p>But unfortunately the following code also works:</p> <pre><code>MyClass x; x.vec() = vector&lt;int&gt;(); </code></pre> <p>I like to disallow this, but i did only find the solution to return a pointer of type <code>vector&lt;int&gt; *</code>. But i learned pointers are 'evil' and i shouldn't use them directly, i have to use smart pointers. I think for this problem a smart pointer is useless, so i don't know how to solve this simple problem:-/</p> <p>Or is just a simple pointer the cleanest solution?</p> <p>best regards</p> <p>Kevin</p> <p>-edit-</p> <p>In general i like to make something that can be used like the follwing C# class:</p> <pre><code>public class MyClass { public List&lt;int&gt; List { get; private set; } public MyClass() { List = new List&lt;int&gt;(); } } </code></pre> <p>It's just an example and i just thought about how to make this in C++. Maybe i some cases i have much more complex classes than <code>vector&lt;int&gt;</code>/<code>List&lt;int&gt;</code> to include into other classes.</p> <p>But maybe it is only possible to do this by defining own methods (=interface) to the internal object.</p>
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    1. USKevin Meier
    1. USKevin Meier
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    1. CODon't return a reference, and add a special function to add values? Having a public function returning a reference to a member variable, is like having the member variable itself public.
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      1. USSome programmer dude
    2. COPointers aren't evil, but don't help here. You should hide the vector detail an provide the right interface to manipulate the data.
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      1. UShansmaad
    3. COif you want to expose all the methods of the vector, don't see any harm in exposing the assignment operator as well (in this case you could also inherit public from vector what would be simpler). if you want to have control and allow only some operators to be public hide the vector and write your own proxy functions
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      1. USYuval
 

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