C++: doubts about visitor pattern

Question

I know what Visitor Pattern is and how to use it; this question is not a duplicate of this one.

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I\'ve got a library where I put most of the reusable code I write,

Answer 1

This doesn't look like a case for the Visitor pattern to me.

I would suggest you have a RenderableShape class that aggregates a Shape object, then create subclasses for each shape. RenderableShape would have a virtual render method.

If you want to support multiple rendering engines, you can have a RenderContext base class that abstracts drawing operations, with subclasses for each rendering engine, each subclass implementing the drawing operations in terms of its rendering engine. You then have RenderableShape::render take a RenderContext as an argument, and draw to it using its abstracted API.