[swift-evolution] [Guidelines, First Argument Labels]: Prepositions inside the parens
dabrahams at apple.com
Tue Feb 9 13:18:00 CST 2016
Having looked at some examples, the API guidelines working group members
that were present this morning agreed we really want prepositions inside
the parentheses of method calls.
Here are some results for the importer; we're still tuning some of the
heuristics but overall we feel very good about the preposition
Note that this is not final wording, but here are the guidelines we're
working with for first argument labels:
A. Try to form a grammatical phrase including the first argument and
describing the primary semantics at the call site.
B. The first argument gets a label when and only when:
1. It does not form part of a grammatical phrase describing the
primary semantics. For example,
[more examples needed]
Note that parameters with defaults never describe the primary
semantics. so are always labeled.
func invert(options options: SomeOptionSet = ) // yes
func invert(_ options: SomeOptionSet = ) // no
2. The method is a factory method; such calls should mirror
initializers, with no preposition. For example,
let x = UIColor(red: r, green: g, blue: b)
let y = monitor.makeColor(red: r, green: g, blue: b)
3. It is part of a prepositional phrase
a. The label normally starts with the preposition.
x.move(from: a, to: b)
x.loadValues(forKeys: ["fox", "box", "lox"])
b. ...unless the preposition would break a very tight association
x.moveTo(x: a, y: b)
[encourage grouping parameters into higher-level concepts,
e.g. Point, in these cases]
Feedback most welcome, of course.
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