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Bug in unapply #1061

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Merged
merged 2 commits into from
May 21, 2018
Merged

Bug in unapply #1061

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c5f969a
Bug in unapply
luiru72 Apr 26, 2018
4de0733
Modified example according to code changes
Apr 26, 2018
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14 changes: 10 additions & 4 deletions _tour/extractor-objects.md
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Original file line number Diff line number Diff line change
Expand Up @@ -23,8 +23,8 @@ object CustomerID {
def apply(name: String) = s"$name--${Random.nextLong}"

def unapply(customerID: String): Option[String] = {
val name = customerID.split("--").head
if (name.nonEmpty) Some(name) else None
val stringArray: Array[String] = customerID.split("--")
if (stringArray.tail.nonEmpty) Some(stringArray.head) else None
}
}

Expand All @@ -45,12 +45,18 @@ val CustomerID(name) = customer2ID
println(name) // prints Nico
```

This is equivalent to `val name = CustomerID.unapply(customer2ID).get`. If there is no match, a `scala.MatchError` is thrown:
This is equivalent to `val name = CustomerID.unapply(customer2ID).get`.

```tut:fail
```tut
val CustomerID(name2) = "--asdfasdfasdf"
```

If there is no match, a `scala.MatchError` is thrown:

```tut:fail
val CustomerID(name3) = "-asdfasdfasdf"
```

The return type of an `unapply` should be chosen as follows:

* If it is just a test, return a `Boolean`. For instance `case even()`.
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