Subject: Re: std::variant - going from Alternative& to the enclosing variant&
From: Ville Voutilainen (ville.voutilainen_at_[hidden])
Date: 2020-08-21 09:22:29
On Fri, 21 Aug 2020 at 17:17, Victor Khomenko
> Thanks Ville,
> >Use a lambda as a visitor and capture the variant in the lambda?
> This won't work if the visitor requires very different processing for different Alternatives. My proposed workaround with a pointer in a visitor is similar to what you suggest, but your solution is restricted to the case when a single lambda can handle every alternative.
A single lambda can handle every alternative. You can do an
if-constexpr in a polymorphic lambda, and handle different
cases in any way you please.
If you want different functions for different alternatives, write a
function object that provides access to the variant.
I suppose we could add a new visit-function that provides the variant
itself as a parameter to the visitor. I'm not entirely
sure whether that's necessary, because the work-arounds are not that
complicated to write.
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