Finder returns ElementInfo with const Element

[JaimeIvanCervantes]

I'm trying to use Finder to get a reference to an Element, and then accept a Visitor from this element, but I'm getting the following error:

candidate function not viable: 'this' argument has type 'const svgdom::Element', but method is not marked const

The problem is that Finder returns ElementInfo with const svgdom::Element& e instead of svgdom::Element& e, so the Element can't be modified.

Here's the code that is causing the error:

auto ref = finder.findById(e.getLocalIdFromIri());
if (!ref) {
     return;
}

class MyVisitor : public Visitor {
public:
   virtual void defaultVisit(Element& e) override {
      // Modify Element here
   }
} myVisitor;

ref->e.accept(myVisitor);

Using Finder to modify Elements seems like a useful pattern to me, otherwise I would have to write my own implementation of Finder with non-constant Element, what do you think?

[igagis]

The Finder class actually does caching, so it does not suppose there will be any modifications to the SVG tree, this is why it works with const references.

It is not hard to implement a visitor which will search element by id and return non-const pointer to the element. No caching is needed in this case, I think.

[JaimeIvanCervantes]

I do need the cache for efficiency, so I implemented my own Finder where I only changed the returned Element to non-constant and I modified the CacheCreator to inherit a Visitor instead of a ConstVisitor. I could make a PR if you're interested.

[igagis]

Actually I doubt about caching, because when you modify the SVG tree (add/remove elements) it will invalidate the cache, so I think that caching for non-const finder is actually not a good thing.