ADBA Add type safe newFactory method

[Douglas Surber]

What is the argument for the String version?

> On Jul 19, 2018, at 8:18 AM, Lance Andersen <lance.andersen at oracle.com> wrote:
> 
> We definitely want  the string based version.
> 
> having both factory methods is also OK.  including  an unWrap method is also an option
> 
>> On Jul 19, 2018, at 11:07 AM, Douglas Surber <douglas.surber at oracle.com <mailto:douglas.surber at oracle.com>> wrote:
>> 
>> I don’t have a strong argument one way or the other. Both String and Class seem fine. The most recent push takes a String but I have no objection to changing it if there is a good reason. I’m in no position to judge how significant an "elegant Kotlin reified generic type extension function” would be. 
>> 
>> Douglas
>> 
>>> On Jul 18, 2018, at 2:57 PM, Frédéric Montariol <frederic.montariol at gmail.com <mailto:frederic.montariol at gmail.com>> wrote:
>>> 
>>> I really like the alternative newFactory static method taking a Class parameter :
>>> public static <T extends DataSourceFactory> T newFactory(Class<T> clazz) 
>>> It would allow elegant Kotlin reified generic type extension function !
>>> 
>>> But there is something I don't like, this is the fact that DataSourceFactory.newFactory returns null if no corresponding class is found, causing NPE on next method call : factory.builder()
>>> I would prefer if it throws an Exception.
>>> 
>>> Le ven. 13 juil. 2018 à 19:48, Douglas Surber <douglas.surber at oracle.com <mailto:douglas.surber at oracle.com> <mailto:douglas.surber at oracle.com <mailto:douglas.surber at oracle.com>>> a écrit :
>>> The internal consensus is to change the spec exactly as you suggest and require the explicit cast if that’s what the user wants. I still would like to hear what others think.
>>> 
>>>  public static DataSourceFactory newFactory(String name) { … }
>>> 
>>>  DataSourceFactory factory = DataSourceFactory.newFactory(“my.adba.MyFactory”);
>>> 
>>> or 
>>> 
>>>  MyFactory factory = (MyFactory) DataSourceFactory.newFactory(“my.adba.MyFactory”);
>>> 
>>> Douglas
>>> 
>>> 
>>> 
>>>> On Jul 13, 2018, at 9:46 AM, Douglas Surber <douglas.surber at oracle.com <mailto:douglas.surber at oracle.com> <mailto:douglas.surber at oracle.com <mailto:douglas.surber at oracle.com>>> wrote:
>>>> 
>>>> This is a good question. I defined it the way I did specifically to avoid the explicit cast. I have no strong opinion on which is better. I’ll ask for opinions internally and I hope other members of this list give their thoughts.
>>>> 
>>>> Douglas
>>>> 
>>>>> On Jul 13, 2018, at 8:26 AM, Mark Rotteveel <mark at lawinegevaar.nl <mailto:mark at lawinegevaar.nl> <mailto:mark at lawinegevaar.nl <mailto:mark at lawinegevaar.nl>>> wrote:
>>>>> 
>>>>> The existing DataSourceFactory.newFactory(String name) has an unchecked cast using a (possibly inferred) type parameter.
>>>>> 
>>>>> Would it make sense to add an alternative with the signature:
>>>>> 
>>>>> public static <T extends DataSourceFactory> T newFactory(Class<T> clazz)
>>>>> 
>>>>> When you use this, you are tied to an ADBA implementation at compile time, but it will make this more type-safe.
>>>>> 
>>>>> And maybe the unchecked cast (and type parameter) should be removed from the variant taking a name only.
>>>>> 
>>>>> That is, change the method to
>>>>> 
>>>>> public static DataSourceFactory newFactory(String name) {
>>>>>  if (name == null) throw new IllegalArgumentException("DataSourceFactory name is null");
>>>>>  return ServiceLoader
>>>>>          .load(DataSourceFactory.class)
>>>>>          .stream()
>>>>>          .filter(p -> p.type().getName().equals(name))
>>>>>          .findFirst()
>>>>>          .map(Provider::get)
>>>>>          .orElse(null);
>>>>> }
>>>>> 
>>>>> Any casts would then be the explicit responsibility of the developer, instead of accidental due to type inference.
>>>>> 
>>>>> Mark
>>>>> -- 
>>>>> Mark Rotteveel
>>>> 
>>> 
>> 
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