Hi Kenny
> Just curious, and because I have a distinct lack of imagination: can you
> share a concrete case of this pattern?
class BaseObject<rootType>
{
private let properties: [PartialKeyPath<rootType> : AnyProperty]
init(properties: [PartialKeyPath<rootType> : AnyProperty])
{
self.properties = properties
}
func value<valueType>(for keyPath: KeyPath<rootType, valueType>) -> valueType?
{
guard let property = properties[keyPath] else
{
return nil
}
return property.getValue()
}
func set<valueType>(value: valueType?, for keyPath: KeyPath<rootType,
valueType>)
{
guard let property = properties[keyPath] else
{
return
}
property.set(value: value)
}
}
class Test : BaseObject<Test>
{
var name: String?
{
get
{
return value(for: \.name)!
}
set
{
set(value: newValue, for: \.name)
}
}
var number: Int?
{
get
{
return value(for: \.number)!
}
set
{
set(value: newValue, for: \.number)
}
}
init()
{
super.init(properties: [\Test.name : Property<String>(), \Test.number :
Property<Int>()])
}
}
Without the generic rootType parameter, all the getter and setter methods need
an explicit mention of the derived class for the keypath :
class Test : BaseObject
{
var name: String?
{
get
{
return value(for: \Test.name)!
}
set
{
set(value: newValue, for: \Test.name)
}
}
…
}
It was all so simple in C# :(
Joanna
--
Joanna Carter
Carter Consulting
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