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This is just one example, but moves are always bitwise, correct? So if I want an object to track all users of it in C++, I can just make a smart pointer for it
by dataflow 3y ago
This is just one example, but moves are always bitwise, correct? So if I want an object to track all users of it in C++, I can just make a smart pointer for it whose copy/move/destruction operations notify the object about each event. How would you do that in Rust? (Similarly, what if I want a relative pointer?)
- remram 3y agoYou can track all of this (things like Rc or Arc do) except move. Relative pointers are possible, depending on what you mean. Making this safe (e.g. preventing users of that type from breaking the relative addressing) is done via the Pin type.
- dataflow 3y ago> You can track all of this (things like Rc or Arc do) except move. Which means you can't track this. Tracking moves is fundamental here. > Relative pointers are possible, depending on what you mean. Pretty sure they're not possible in the sense I mean, for the same reason as above - you need custom moves for this. I'm referring to a pointer (not an offset; a pointer) that automatically adjusts itself when copied or moved. So that it always points somewhere N blocks before/after itself. These are just two examples, to get the point across that Rust actually lacks some capabilities (since somehow that surprises people). You can find more.
- remram 3y ago> Tracking moves is fundamental here. I mean, arguably. If it is fundamental for your hypothetical use case, then sure, but this is not required for a lot of use cases, like smart pointers.