Highs::passModel() takes the model by value

[cvanaret]

Hi,
Is there a good reason why Highs::passModel() takes the model (HighsModel or HighsLp) by value, instead of (const) reference?
This means the model (cost, bounds, constraint matrix, Hessian) is copied when this function is called, which is expensive when the model is large.

[jajhall]

I didn't write this, but I believe that one reason is so that we can use std::move thus

h.passModel(std::move(lpmodel));

It also allows us to do things like this

HighsStatus Highs::passModel(HighsLp lp) {
HighsModel model;
model.lp_ = std::move(lp);
return passModel(std::move(model));
}

when only a HighsLp instance is passed, and this couldn't be done if a const reference were passed. Maybe we could overload with additional methods

Highs::passModel(const &HighsModel model)

Highs::passModel(const &HighsLp lp)

Note that HiGHS operates on its own internal model instance, rather than the model that is passed to it, since it needs to be able to modify the user's model.

[cvanaret]

Got it, you make a copy and steal it, so that you can modify it internally. Thanks for the quick reply!