trait TrySugar extends AnyRef
Trait providing an implicit class that adds a toOr
method to
Try
, which converts Success
to Good
,
and Failure
to Bad
, as well as a validating
method,
which takes one or more validation functions and returns either the
same Try
if either the Try
had already failed or its value
passes all the functions, or ValidationFailedException
containing an error message
describing the first validation that failed.
Here's an example validation method, which passes if the given Int
is evenly
divisible by 10 (i.e., the result will be Pass
). If the value does not pass
this test, the result is a Fail
containing a helpful error message string.
scala> import org.scalactic._ import org.scalactic._ scala> import TrySugar._ import TrySugar._ scala> import scala.util.Try import scala.util.Try scala> def isRound(i: Int): Validation[ErrorMessage] = | if (i % 10 == 0) Pass else Fail(i + " was not a round number") isRound: (i: Int)org.scalactic.Validation[org.scalactic.ErrorMessage]
Validation will be attempted on a successful Try
. If the validation succeeds, the
resulting Try
will be the same successful Try
with the same value. (A
"validation" only transforms the Try
if the validation fails, otherwise it is the
same Try
. The only difference is its value has now been proven valid.)
In the following example, a successful Try[Int]
with the value 100
passes the validation (which checks whether 100 is evenly divisible by 10), therefore
the result of the validating
call is the same successful Try
with the same value.
scala> val try100 = Try(100) try100: scala.util.Try[Int] = Success(100) scala> val round100 = try100.validating(isRound) round100: scala.util.Try[Int] = Success(100)
If validation fails, the successful Try
will be transformed into a failed one, with
a ValidationFailedException
that contains the error message
returned by the validation function. In the following example, 42 fails the validation because it
is not evenly divisible by 10:
scala> val try42 = Try(42) try42: scala.util.Try[Int] = Success(42) scala> val round42 = try42.validating(isRound) round42: scala.util.Try[Int] = Failure(org.scalactic.exceptions.ValidationFailedException: 42 was not a round number)
If validating
is called on a failed Try
, it just returns the same failed Try
:
scala> val tryEx = Try[Int] { throw new Exception("oops!") } tryEx: scala.util.Try[Int] = Failure(java.lang.Exception: oops!) scala> val roundEx = tryEx.validating(isRound) roundEx: scala.util.Try[Int] = Failure(java.lang.Exception: oops!)
The validating
method accepts one or more validation functions. If you
pass more than one, they will be tried in order up until the first failure, whose
error message will appear in the ValidationFailedException
. In other words,
validating
will short circuit at the first error and return that. It
will not accumulate errors. For example, the following validation will short circuit
after the isDivBy3
function fails:
scala> def isDivBy3(i: Int): Validation[ErrorMessage] = | if (i % 3 == 0) Pass else Fail(i + " was not divisible by 3") isDivBy3: (i: Int)org.scalactic.Validation[org.scalactic.ErrorMessage] scala> def isAnswerToLifeTheUniverseAndEverything(i: Int): Validation[ErrorMessage] = | if (i == 42) Pass else Fail(i + " did not equal 42") isAnswerToLifeTheUniverseAndEverything: (i: Int)org.scalactic.Validation[org.scalactic.ErrorMessage] scala> try100.validating(isRound, isDivBy3, isAnswerToLifeTheUniverseAndEverything) res0: scala.util.Try[Int] = Failure(org.scalactic.exceptions.ValidationFailedException: 100 was not divisible by 3)
Here are some examples of the toOr
method:
scala> try100.toOr res1: org.scalactic.Or[Int,Throwable] = Good(100) scala> tryEx.toOr res2: org.scalactic.Or[Int,Throwable] = Bad(java.lang.Exception: oops!)
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- implicit class Tryizer[T] extends AnyRef
Implicit class that adds a
toOr
method toTry
, which convertsSuccess
toGood
, andFailure
toBad
, as well as avalidation
method, which takes one or more functions that validate theFuture
's value.Implicit class that adds a
toOr
method toTry
, which convertsSuccess
toGood
, andFailure
toBad
, as well as avalidation
method, which takes one or more functions that validate theFuture
's value.See the main documentation for trait
TrySugar
for more detail and examples.
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