[swift-evolution] [Proposal Draft] Flexible memberwise initialization

[Thorsten Seitz]

> Am 22.12.2015 um 05:43 schrieb Matthew Johnson via swift-evolution <swift-evolution at swift.org>:
> 
> What do you think the downsides are of synthesizing memberwise initialization for properties with an “initial value”?  

When using the memberwise initializer those properties are always assigned a value twice. First the initial value and then the value provided by the initializer. The first value is constructed and assigned unnecessarily and in corner cases this might even be problematical, e.g. if creating a value of a certain kind has a side effect like incrementing an instance counter or logging something.

-Thorsten