我有以下（简化）代码：
Illuminate\Database\Eloquent\Collection Object
(
[items:protected] => Array
(
[0] => App\BookingDates Object
(
[connection:protected] =>
[table:protected] =>
[primaryKey:protected] => id
[perPage:protected] => 15
[incrementing] => 1
[timestamps] => 1
[attributes:protected] => Array
(
[id] => 267
[slot] => All Day
)
[original:protected] => Array
(
[id] => 267
[slot] => All Day
)
[relations:protected] => Array
(
)
[hidden:protected] => Array
(
)
[visible:protected] => Array
(
)
[appends:protected] => Array
(
)
[fillable:protected] => Array
(
)
[guarded:protected] => Array
(
[0] => *
)
[dates:protected] => Array
(
)
[casts:protected] => Array
(
)
[touches:protected] => Array
(
)
[observables:protected] => Array
(
)
[with:protected] => Array
(
)
[morphClass:protected] =>
[exists] => 1
)
[1] => App\BookingDates Object
(
[connection:protected] =>
[table:protected] =>
[primaryKey:protected] => id
[perPage:protected] => 15
[incrementing] => 1
[timestamps] => 1
[attributes:protected] => Array
(
[id] => 265
[slot] => Morning
)
[original:protected] => Array
(
[id] => 265
[slot] => Morning
)
[relations:protected] => Array
(
)
[hidden:protected] => Array
(
)
[visible:protected] => Array
(
)
[appends:protected] => Array
(
)
[fillable:protected] => Array
(
)
[guarded:protected] => Array
(
[0] => *
)
[dates:protected] => Array
(
)
[casts:protected] => Array
(
)
[touches:protected] => Array
(
)
[observables:protected] => Array
(
)
[with:protected] => Array
(
)
[morphClass:protected] =>
[exists] => 1
)
[2] => App\BookingDates Object
(
[connection:protected] =>
[table:protected] =>
[primaryKey:protected] => id
[perPage:protected] => 15
[incrementing] => 1
[timestamps] => 1
[attributes:protected] => Array
(
[id] => 266
[slot] => Afternoon
)
[original:protected] => Array
(
[id] => 266
[slot] => Afternoon
)
[relations:protected] => Array
(
)
[hidden:protected] => Array
(
)
[visible:protected] => Array
(
)
[appends:protected] => Array
(
)
[fillable:protected] => Array
(
)
[guarded:protected] => Array
(
[0] => *
)
[dates:protected] => Array
(
)
[casts:protected] => Array
(
)
[touches:protected] => Array
(
)
[observables:protected] => Array
(
)
[with:protected] => Array
(
)
[morphClass:protected] =>
[exists] => 1
)
)
)
现在我想在case class Value[T](value: T)
trait Absable[In,Out] {
def absoluteValue(in: In): Out
}
implicit class AbsValue[In, Out](in: Value[In]) {
def abs()(implicit ev: Absable[In, Out]): Value[Out] = Value(ev.absoluteValue(in.value))
}
implicit def AbsNumeric[A : Numeric] = new Absable[A, A] {
def absoluteValue(in: A) = implicitly[Numeric[A]].abs(in)
}
上使用abs函数：
Value我在隐式参数前添加了一个空参数列表，以便为调用者提供更大的灵活性，但是现在当我在调用站点省略空列表时，编译器无法找到隐含的...所以现在而不是更灵活的调用者会使编译错误混乱 我不明白离开参数列表会如何影响类型推断或隐式解析。
我正在使用scala 2.11.6