I meant in the Scala code but forgot to say so. Also, blocks can't be part
of expressions in Java like in Scala so your Java code won't compile.
On Jul 27, 2012 7:25 AM, "Kevin Wright" <[email protected]> wrote:
> I think you do for the (a==null) check, because there are two statements
> against the failure condition (the assignment to b, and the second check).
> if a is absent, then neither doSomethingIfBWasAbsent nor doSomethingWithB
> should be called!
>
> The second block can go though, and taking advantage of precedence for ==
> gives:
>
> final A a = getA();
> a == null ? doSomethingIfAWasAbsent() : {
> final B b = getBFrom(a);
> b == null ? doSomethingIfBWasAbsent() :
> doSomethingWithB(b);
> };
>
> Though my personal preference would be to retain the bracketing for the
> equality checks, I find it easier to read that way. Past exposure to LISP
> may have some influence on this though :)
>
>
> On 27 July 2012 11:09, Ricky Clarkson <[email protected]> wrote:
>
>> Kevin, I believe you don't need any of the (){} characters there, but
>> maybe I'm missing something.
>> On Jul 27, 2012 6:04 AM, "Kevin Wright" <[email protected]> wrote:
>>
>>> That's a bit open-ended, are you thinking of a particular construct that
>>> you think would be challenging to convert?
>>>
>>> As another trivial example, something like this:
>>>
>>> final A a = getA();
>>> if (a != null) {
>>> final B b = getBFrom(a);
>>> if (b != null) {
>>> doSomethingWithB(b);
>>> } else {
>>> doSomethingIfBWasAbsent();
>>> }
>>> } else {
>>> doSomethingIfAWasAbsent();
>>> }
>>>
>>>
>>> Or with the tertiary operator:
>>>
>>> final A a = getA();
>>> (a == null) ? doSomethingIfAWasAbsent() : {
>>> final B b = getBFrom(a);
>>> (b == null) ? doSomethingIfBWasAbsent() : {
>>> doSomethingWithB(b);
>>> }
>>> };
>>>
>>>
>>> Could be written in Scala as:
>>>
>>> val a = getA
>>> val b = a flatMap {getBFrom}
>>> a getOrElse {doSomethingIfAWasAbsent()}
>>> b getOrElse {doSomethingIfBWasAbsent()}
>>> b forEach {doSomethingWithB}
>>>
>>>
>>>
>>>
>>>
>>> On 27 July 2012 04:16, Cédric Beust ♔ <[email protected]> wrote:
>>>
>>>> Yes but that's the most trivial case. For example, experiment with your
>>>> Option code when the original code has else's.
>>>>
>>>> --
>>>> Cédric
>>>>
>>>>
>>>>
>>>>
>>>> On Thu, Jul 26, 2012 at 5:30 PM, clay <[email protected]> wrote:
>>>>
>>>>> Here is a simple example that illustrates the benefit of Option beyond
>>>>> avoiding null exceptions:
>>>>>
>>>>> Here is a traditional piece of logic using traditional null if-checks.
>>>>> This is using Scala syntax but would be equivalent in Java.
>>>>>
>>>>> val variableAMayBeNull: A = methodThatMayProduceA();
>>>>> if (variableAMayBeNull != null) {
>>>>> val variableBMayBeNull: B = tryToGetBFromA(variableAMayBeNull);
>>>>>
>>>>> if (variableBMayBeNull != null) {
>>>>> doSomethingWithNonNullB(variableBMayBeNull);
>>>>> }
>>>>> }
>>>>>
>>>>> Same logic using Option. This is Scala syntax. Java can do this but
>>>>> not as nicely until it gets lambdas.
>>>>>
>>>>> val variableAMayBeNull: Option[A] = methodThatMayProduceA();
>>>>> val variableBMayBeNull: Option[B] =
>>>>> variableAMayBeNull.flatMap(tryToGetBFromA);
>>>>> variableBMayBeNull.foreach(doSomethingWithNonNullB);
>>>>>
>>>>> Both blocks are logically equivalent, but the Option route is much
>>>>> more concise, elegant, and maintainable. The if-logic is moved from the
>>>>> end
>>>>> application code to inside of the Option class. Since this type of logic
>>>>> is
>>>>> so common in application code, the code simplification benefits are quite
>>>>> large.
>>>>>
>>>>>
>>> --
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