On: Apple's auto layout and visual format language for...

[melling]

I stopped using the visual format language. It was great for a while. The new constraints are much better with type checking:

        NSLayoutConstraint.activate([
            button.centerXAnchor.constraint(equalTo: view.centerXAnchor),
            button.centerYAnchor.constraint(equalTo: view.centerYAnchor, constant: 0)
            ])

[lilyball → melling]

They're even better when you define some operators for them:

  NSLayoutConstraint.activate([
      button.centerXAnchor ≈ view.centerXAnchor,
      button.centerYAnchor ≈ view.centerYAnchor + 10
      ])

[saagarjha → lilyball]

Anecdotally, that way lies ballooning Swift compile times.

[vlozko → saagarjha]

It’s not anecdotal. We used Anchorage for some time before dropping it for this very reason. There’s a compiler warning available to you to let you know if any line or function takes more than a certain amount of time to compile. Our autolayout code that used Anchorage became the #1 source of warnings when we enabled it.

[lilyball → vlozko]

I've been using my operators for a long time without a problem. I think the secret is the fact that I'm using custom operators that have no other overloads, which avoids the combinatorial type system explosion during evaluation. The operators I use are ≈, ≤, and ≥ (which can all be typed on a US English keyboard using the option key). I admit there are overloads on the normal arithmetic operators for doing constants/multipliers too, but those haven't ended up as a problem (it's quite possible that the use of the custom operators constrains the expression enough that the arithmetic ones aren't a problem).

For context, I've had the options on to warn on expensive expressions for a long time and we use a lot of these operators everywhere and I think only once did we ever have an autolayout line flagged, and that was due to a complicated expression used to come up with the constant value.

[dep_b → vlozko]

Same for Cartography.

[dep_b → lilyball]

Using vanilla autolayouts is pretty masochistic.