Enum enhancement

[Brian Goetz]

Agree that it's pretty and builds on general building blocks, rather 
than crafting a bespoke solution.  On the other hand, if you expect "not 
found" to be uncommon, you're creating unnecessary garbage on every 
lookup (until we have value types), and, as #1 of your mail pointed out, 
you don't like APIs that necessarily create garbage!  (Though EA is more 
likely to win here than with the array, and when we have values, that 
will get better still.)





On 12/7/2018 9:58 AM, Giguere, Thierry wrote:
>
> I do agree that Optional is the way to go!
>
> Thierry Giguère
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> *From:*Maurizio Cimadamore [mailto:maurizio.cimadamore at oracle.com]
> *Sent:* December 7, 2018 9:55 AM
> *To:* Tagir Valeev <amaembo at gmail.com>; Brian Goetz 
> <brian.goetz at oracle.com>
> *Cc:* amber-dev at openjdk.java.net; Giguere, Thierry 
> <thierry.giguere at bnc.ca>
> *Subject:* Re: Enum enhancement
>
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> On 07/12/2018 14:36, Tagir Valeev wrote: > As for (2) probably 
> Optional findValue(String name) would be better, as > you may decide 
> what to do if it's absent using all the optional API. I like this 
> suggestion! Maurizio > > With best regards, > Tagir Valeev. > > пт, 7 
> дек. 2018 г., 21:28 Brian Goetz brian.goetz at oracle.com 
> <mailto:brian.goetz at oracle.com>: > >> (1) is already tracked as >> >> 
> https://bugs.openjdk.java.net/browse/JDK-8073381 
> <https://bugs.openjdk.java.net/browse/JDK-8073381> >> >> It is not as 
> "easy" as you think in that these enum methods are >> generated by the 
> compiler, not as ordinary library code, but it's not >> prohibited. >> 
> >> (2) is not unreasonable. As there's no language component to it, 
> you >> could take this directly to corelibs-dev for further 
> evaluation. >> >> On 12/7/2018 9:13 AM, Giguere, Thierry wrote: >>> 
> Hello, >>> >>> Related to the follow link and JEP 301 >> : >>> >> 
> http://mail.openjdk.java.net/pipermail/amber-spec-experts/2018-December/000876.html 
> >>> What is also missing and long-time due for enum right now and 
> could be >> added quickly is more methods: >>> 1) We need to be able 
> to iterate efficiently on enum. Currently calling >> method T[] 
> values() duplicate the internal array. Moreover you need to go >> 
> through method Arrays.stream() to convert the newly created array to 
> >> stream. Adding a stream() method and a forEach() method would help 
> fix this >> problem. Optionally a iterator() method could be provided 
> >>> Arrays.stream(MyEnum.values()).forEach(); >>> >>> could be 
> replaced by something like : >>> >>> MyEnum.forEach(); >>> >>> And >>> 
> >>> Arrays.stream(MyEnum.values()).map(... >>> >>> could be written : 
> >>> >>> MyEnum.stream().map(... >>> >>> 2) T valueOfOrDefault : pretty 
> much like getOrDefault of the map >> interface. This method don't 
> throw exception and fallback on default value. >> That would ease use 
> of enum in stream / lambda programming >>> @Nonnull >>> MyEnum myEnum 
> = MyEnum.DEFAULT_VALUE; >>> >>> try { >>> myEnum = 
> MyEnum.valueOf(...); >>> } catch (NullPointerException | 
> IllegalArgumentException e) >> { >>> // Just keep going with on the 
> default value >>> } >>> >>> Since exception are thrown it doesn't fit 
> very well in stream / lambda >> usage. Something like this : >>> 
> MyData.stream().map(MyEnum::valueOf).forEach() >>> >>> Must be 
> converted to : >>> >>> MyData.stream().map(d -> { >>> try { >>> return 
> >> MyEnum.valueOf(...); >>> } catch (Exception e) { >>> return >> 
> MyEnum.DEFAULT_VALUE; >>> } >>> }).forEach(); >>> >>> It would be 
> great to write at least something like : >>> >>> MyData.stream().map(d 
> -> MyEnum.valueOfOrDefault(d, >> MyEnum.DEFAULT_VALUE)).forEach(); >>> 
> My feeling is these enhancement could be easily and quickly added >>> 
> >>> Thierry Giguère >>> >>> CONFIDENTIALITÉ : Ce document est destiné 
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