[os overlay] Please provide os_log variant that takes `[CVarArg]`

Originator:zach
Number:rdar://33203955 Date Originated:July 9 2017, 4:18 PM
Status:Open Resolved:false
Product:Developer Tools Product Version:Xcode Version 9.0 beta 2 (9M137d)
Classification:Enhancement Reproducible:N/A
 
Summary:
The Core Team has lamented before that no public API should be provided that only takes Swift varargs (i.e., the `Foo…` pattern) because it prevents API composition.

The os_log overlay for Swift does only this.

See also: https://github.com/apple/swift/blob/master/stdlib/public/SDK/os/os_log.swift#L23

Steps to Reproduce:
Attempt to use os_log in API composition.

Expected Results:
I can chain transformed argument lists into the overlay's os_log function.

Observed Results:
I cannot.

Version:
Xcode Version 9.0 beta 2 (9M137d)

Notes:
See also: https://github.com/apple/swift/blob/master/stdlib/public/SDK/os/os_log.swift#L23

The extra function would have an identical implementation, just a different prototype. Heck, I might just PR it and reference this radar.

Allowing this kind of composition can allow developers to:

- Implement more Swifty providers of subsystem/categories.
- Provide custom transformations for log values without the extra expense of transforming when a log level is disabled.
- Not have to perform this same shimming using C hacks that might break depending on the OS version.

Configuration:
N/A

Comments


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