On 31 December 2014 at 10:55, Anthony Shipman wrote: > On Wed, 31 Dec 2014 09:18:35 pm Jonathan Wakely wrote: >> What exactly are you worried about, the compiler failing to perform >> moves, or your code missing opportunities to move? >> >> The former will very rarely be a problem, the latter can be solved by >> understanding the language better. >> > Well there's the rub. When there may or may not be an automatically generated > move assignment or constructor That's easy to know. It's better to get into the habit of declaring defaulted move operations anyway, instead of relying on implicitly generated ones. > and the compiler may or may not choose a move > based on the risk of an exception being thrown Nope, the compiler makes no such choice. The standard library might choose not to move in such cases, but it does so by initializing copies from lvalues not rvalues, so the compiler has no choice about whether to move or not. > and with the return value > optimisation etc it's rather difficult to predict exactly what will happen. If the source object is an rvalue or is a local variable being returned from a function then it's eligble for moving. Otherwise not. That covers pretty much every common case.
