[swift-evolution] [Pitch] Version-pinned patching of public declarations

[Dave Abrahams]

> On Dec 31, 2015, at 4:16 PM, Joe Groff <jgroff at apple.com> wrote:
> 
> 
>> On Dec 31, 2015, at 1:20 PM, Dave Abrahams <dabrahams at apple.com> wrote:
>> 
>> Hi Joe,
>> 
>> Can you compare the developer experience with/without this feature, e.g. paint some scenarios and describe what one would have to do to deal with it?
> 
> If a binary framework ships with a bug, and that bug is exercised as a second-order effect of other framework functionality, then without dynamic patching, your choices amount to trying to avoid or work around the bug, or reimplementing the functionality between you and the bug yourself (or replacing it with a third party library). If the bug lies somewhere deep like in text layout or affine transform math, or in something complex like PDF rendering (all bugs that have really shipped), replacing the functionality might not be practical, and avoiding the bug might not be possible.

Sorry, I had something much more specific, including code examples, in mind.  You’re not telling me how you’d use this feature to solve the problem, or what the alternative solutions would look like without this feature.  That’s what I need to see in order to understand the proposal.

-Dave