Factory Macros

[hmlongco]

There's an extremely experimental branch (macros) now available that explores Swift Macros in Factory.

You can read more about it here: Factory: Macro Misadventures

[scottrhoyt]

Very cool exploration! I applaud the effort to try and prevent Factory from leaking too much into the codebase.

Another consideration I've run into when playing around with macros is compile time. Depending on the swift-syntax library brings in a lot of overhead. While you often get the benefit of incremental compilation, I'm sure I'm not alone in needing to clean my derived data folder more than I'd like to solve Xcode issues. I recently decided to strip macro dependencies out of a test target because I was getting annoyed at how long running tests was taking both locally and on CI.

[hmlongco]

Given that it's predominately Factory definitions and that those are usually concentrated in just a few files, I'm not sure just how much build time is added.

Not seeing an appreciable difference in Factory test and demo build times.

Regardless, I guess I'll have to wait to see what WWDC brings to Swift macros before I decide to add these to the project. But my goal is to have library targets with and w/o macro support so that people can use them (or not) as needed.

[scottrhoyt]

Makes sense!

On my machine, a clean build of swift-syntax alone takes about 24s, so I was adding that every time I did a clean build of my macro-containing libraries. Not huge, but it was noticeable and a bit annoying because unfortunately it seems that Xcode needs a clean more than I'd like.

Factory builds in about 16s currently, so I would have imagined that adding macros would increase clean build time for Factory a good deal. Obviously not a problem if there are already other libraries building swift-syntax or you don't have to do a clean build often, so ymmv.

Thanks for the great library and for continuing to look to improve it!

[scottrhoyt]

Looks like some help for this issue may be coming "soon": swiftlang/swift-syntax#2421