why two evaluation results are different?

[jojogh]

I want to use boost yap to do some small example, the codes are below, why I put the expression into an operator or member function in a structure, the two evaluation results are different? I am looking forward to your reply, many thanks! new4.cpp.txt

[jojogh]

seems no one would answer my question.

[greole]

It seems like I experience a similar issue when using stateful terminals created from rvalue references. I'll have look if I can figure out what is going on...

[jojogh]

many thanks

greole notifications@github.com 于2020年2月17日周一 上午1:19写道：

It seems like I experience a similar issue when using stateful terminals created from rvalue references. I'll have look if I can figure out what is going on...

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[tzlaine]

struct eval 
{
    auto operator() (double a, double b) {
        auto lhs_w = boost::yap::make_terminal<tarray_expr>(std::move(a));
        auto rhs_w = boost::yap::make_terminal<tarray_expr>(std::move(b));

        return lhs_w + rhs_w;
    }
};

This returns a dangling reference to both lhs_w and rhs_w. The documentation explains why. If you std::move them both, as in return std::move(lhs_w) + std::move(rhs_w);, your code will work as intended.