-1 on #autoInit for properties declaration. Init should explicitly shows
what parameters it will get and what will be assiged. I believe in case we
want this feature, "self." prefix must be in init declaration in parameter
list, with or without type(I prefer with type):
init( self.foo: String, self.bar: String, baz: Int){..}
or
init( self.foo, self.bar, baz: Int){..}
In this case IMO it is obvious that this init will set self.foo&self.bar by
provided values from caller. And it is clear(in first variant) what is the
types of parameters for init(let's imaging a class with long list of
properties/internal structs/classes/enums, number of initializers then. And
you see init( self.foo, self.bar, baz: Int) - what is the type of first
parameter for this initializer? You have to scroll up to defenition of
self.foo, then find self.bar definition etc. This is why I prefer explicit
type declaration in init. Also this protects against automatic change of
init parameter types after you changed type of property - i.e. you have to
explicity change init declaration i.e. you must be sure that you want to
change init method)
On 19.04.2016 0:51, Haravikk via swift-evolution wrote:
I agree with the intent of this, but perhaps not the solution; sticking
with the original example, simply being able to have an implied initialiser
for classes, as we have for structs, would be enough, for example:
class Foo {
let foo:String
let bar:String
let baz:Int
var barCount:Int { return self.bar.characters.count } // Computed
property, could be lazy instead I think?
// Implied init(foo:String, bar:String, baz:Int)
}
Personally I’m not a fan of the syntax, I wonder if an #autoinit or such
directive could be used to indicate properties that should be initialised
automatically where possible, like so:
class Foo {
#autoInit let foo:String
#autoInit let bar:String
#autoInit let baz:Int
let barCount:Int
init(foo:String, bar:String, baz:Int) {
// foo, bar, baz handled behind the scenes
self.barCount = bar.characters.count
}
}
(or it could be on the parameters of the init function, might be clearer
that way)
Just an idea anyway
On 16 Apr 2016, at 14:17, Jonathan Hull via swift-evolution
<swift-evolution@swift.org <mailto:swift-evolution@swift.org>> wrote:
Since we know the types of the properties, how about we replace the type
in the signature with either an indication that the property should be
automatically set, or better yet, the property which should be set:
class Foo
{
let foo : String
let bar : String
let barCount : Int
let baz : Int
init(foo: self.foo, bar: self.bar, baz: self.baz)
{
self.barCount = bar.characters.count
}
}
That way you don’t always have to have the init’s parameter names match
the names of the properties they set (even though they often would). We
could also allow a leading dot as a shorthand for ‘self.’
init(foo: .foo, bar: .bar, baz: .baz)
I think I like explicit ‘self.’ better, but that may just be my
preference. In either case, the generated interface would show the
actual type.
// init(foo: String, bar: String, baz: Int)
Thanks,
Jon
This is a common pattern for initialisers at the moment:
class Foo
{
let foo : String
let bar : String
let barCount : Int
let baz : Int
init(foo: String, bar: String, baz: Int)
{
self.foo = foo
self.bar = bar
self.baz = baz
barCount = bar.characters.count
}
}
This involves a lot of using 'self.'. For those who prefer not to use
'self.' explicitly everywhere, this is probably the main place it gets
used. It's a lot of boilerplate code.
How would it be if, like default variables, we could pack some of that
information into the argument tuple, and unify parameters with properties
immediately?
class Foo
{
let foo : String
let bar : String
let barCount : Int
let baz : Int
init(self.foo: String, self.bar: String, self.baz: Int)
{
barCount = bar.characters.count
}
}
Less boilerplate, more focus on the properties which need to be generated.
Thoughts?
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