3 ms·

Calling moving objects 'stealing', calling for 'dishonest citizens' etc gives moving a bad connotation which it hardly deserves at all, especially not in correc

by stinos 11y ago

Calling moving objects 'stealing', calling for 'dishonest citizens' etc gives moving a bad connotation which it hardly deserves at all, especially not in correct code. The main reason is that the object which is moved from is usually not going to be used anymore anyway so it doesn't matter what happens to it's content. That is just how it is meant to be used by the folks designing it: transferring content. Calling that stealing would be like calling the righteous transport of goods from one warehouse to another warehouse stealing: it is not, all involved parties know that after the transaction the first warehouse will be empty and the latter is full. The premise set in this article (first move, then use the object again and expect it to have content) goes against this. Which is actually fine, unless of course you expect that moving somehow leaves the original intact. Which it doesn't, that is what copying is supposed to be used for. At least in my opinion.

enqk 11y ago
I always think of the X in std::move(X) as an object that is about to be destructed. I.e. treat a bit the std::move cast as a marker for destruction
quicknir 11y ago
Dude, the stealing etc was clearly tongue in cheek. It seems like the example I picked was a bit unfortunate in the following sense: a couple of people have already misinterpreted the point of the article to be that foo still had content after I moved its string (I won't use stole anymore, seems like a touchy subject). That's not the point, the point is that the invariants are maintained, which is the requirement for a valid state. I could have reset m_set at the same time as I set m_cached to false, it would still be just as correct. Edit: I have modified the post slightly so that it's a bit clearer that what I'm after is a valid state for foo, not to maintain the specific things that were inserted.

by stinos 11y ago

enqk 11y ago

I always think of the X in std::move(X) as an object that is about to be destructed. I.e. treat a bit the std::move cast as a marker for destruction

quicknir 11y ago

Dude, the stealing etc was clearly tongue in cheek. It seems like the example I picked was a bit unfortunate in the following sense: a couple of people have already misinterpreted the point of the article to be that foo still had content after I moved its string (I won't use stole anymore, seems like a touchy subject). That's not the point, the point is that the invariants are maintained, which is the requirement for a valid state. I could have reset m_set at the same time as I set m_cached to false, it would still be just as correct. Edit: I have modified the post slightly so that it's a bit clearer that what I'm after is a valid state for foo, not to maintain the specific things that were inserted.