CODEWITHSUNDEEP
c++boost
Vladimir Tsyshnatiy
Vladimir Tsyshnatiy

Reputation: 1069

Boost variant and visitor

I have 2 structures Base and Derived and boost:variant with 2 types. 

struct Base : public boost::static_visitor<>
{
    virtual void operator(Type1& t) {}
    virtual void operator(Type2& t) {}
};

What I want to do is do define Derived as:

struct Derived : public Base
{
    void operator(Type1& t) { /*some impl*/ }
};

I do not override operator for the Type2 assuming it is defined in Base and empty.

For some reason if I write

Derived visitor;
boost::apply_visitor(visitor, variant);

I get error: no match for call to '(Derived) (Type2&)'

Of course, if I add operator for Type2 into derived it works ok.
Could anyone please help to understand why it is not working without adding operator for Type2?

Upvotes: 1

Views: 109

Answers (1)

Rakete1111
Rakete1111

Reputation: 48968

Name lookup doesn't consider operators in base classes. You need to explicitly bring it in Derived's scope for it to be seen by name lookup:

struct Derived : public Base
{
    void operator()(Type1& t) { /*some impl*/ }
    using Base::operator();
};

Upvotes: 3

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