Why is operator= and copy-constructor NOT implicitly generated in this case?

Question

I have a struct like this:

/* Renderable definition */
    struct Renderable
    {
        Renderable(VertexBufferPtr vertexBuffer, const Mat4& wvpMatrix, const Mat4& worldMatrix, const Vec4& diffuseColor, const float specularFactor) : 
                    mVertexBuffer(vertexBuffer), mTransform(wvpMatrix, worldMatrix), mMaterial(diffuseColor, specularFactor)
        {
        }

        /* Transform definition */
        struct Transform
        {
            Transform(const Mat4& wvpMatrix, const Mat4& worldMatrix) : mWVPMatrix(wvpMatrix), mWorldMatrix(worldMatrix)
            {
            }

            const Mat4 mWVPMatrix;
            const Mat4 mWorldMatrix; 
        };

        /* Material definition */
        struct Material
        {
            Material(const Vec4& diffuseColor, const float specularFactor) : mDiffuseColor(diffuseColor), mSpecularFactor(specularFactor)
            {
            }

            const Vec4 mDiffuseColor;
            const float mSpecularFactor;
        };


        const VertexBufferPtr mVertexBuffer;
        const Transform mTransform;
        const Material mMaterial;
    };

    /* RenderQueue definition */
    typedef std::vector<Renderable> RenderQueue;

When I try to use it in my code like this;

RenderQueue CreateRenderQueue(const Scene* scene);

....

RenderQueue renderQueue(CreateRenderQueue(activeScene));

I get the follow compile error:

c:\program files (x86)\microsoft visual studio 10.0\vc\include\xutility(2514): error C2582: 'operator =' function is unavailable in 'Renderable'

After some digging I came to realise it was because I had not defined the assignment operator and the copy-constructor. I then did so, and voilah! it compiled...

....My question is however, why is the assignment operator and the copy constructor NOT implicitly generated by the compiler? (vs2010) I did not define them, so surely they would be generated?

Thanks

What is `VertexBufferPtr`? Is it copyable? – Ben Voigt Apr 15 '13 at 21:02 — Ben Voigt, Apr 15 '13 at 21:02

score 5 · Accepted Answer · edited Apr 12 '18 at 20:47

5

You have constant class member objects, so you cannot assign those. A copy constructor should be generated, though.

edited Apr 12 '18 at 20:47

alehresmann

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answered Apr 15 '13 at 20:50

Kerrek SB

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You just saved my day, never thought about this before. – Mikhail Aug 22 '13 at 18:41

score 0 · Answer 2 · edited May 23 '17 at 12:28

See the answer to this question, which states the conditions for an implicit default constructor (emphasis mine):

If you do not define a constructor, the compiler will define a default constructor for you

You defined a constructor, hence the implicit default one is not available anymore, it's up to you to define one.

In fact, a few lines below the same answer gives the same rule for all of the essential methods of classes:

If no destructor/copy Constructor/Assignment operator is defined the compiler builds one of those for you

Why is operator= and copy-constructor NOT implicitly generated in this case?

2 Answers2