[fpc-devel] Move operator

[Ryan Joseph]

> On Jul 13, 2019, at 8:21 AM, Jonas Maebe <jonas at freepascal.org> wrote:
> 
> In which scenarios do you need such a custom "move" operator, rather
> than simply allowing the compiler to just copy the data from one place
> to the other without calling a destructor on the old instance?

Not sure off the top of my head what would happen if the user simply wasn’t informed about the operation but it makes me nervous. :) It may be the case though that inside the move operator the most common thing is just to call System.Move anyways. Also if the operator isn’t there then there’s no way to know without a modeswitch or some other syntax that the user wants to calls system.move instead of the Copy operator.

> 
> I can only imagine this would be a problem if your managed record
> constructor/destructor automatically register/unregister pointers to
> these managed record instances in another datastructure, but is that
> valid in any case?

Hmm, not sure what you mean. If look at the bug report (https://bugs.freepascal.org/view.php?id=35825) I did find some bugs relating to nested records and fixed them. You can apply the patch or test with https://github.com/genericptr/freepascal/tree/moveop

Regards,
	Ryan Joseph