Enum enhancement

[Giguere, Thierry]

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 >> >> 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 uniquement à la personne ou à >> l'entité à qui il est adressé. L'information apparaissant dans ce document >> est de nature légalement privilégiée et confidentielle. Si vous n'êtes pas >> le destinataire visé ou la personne chargée de le remettre à son >> destinataire, vous êtes, par la présente, avisé que toute lecture, usage, >> copie ou communication du contenu de ce document est strictement interdit. >> De plus, vous êtes prié de communiquer avec l'expéditeur sans délai ou >> d'écrire à confidentialite at bnc.ca<mailto:confidentialite at bnc.ca> et de détruire ce document >> immédiatement. >>> CONFIDENTIALITY: This document is intended solely for the individual or >> entity to whom it is addressed. The information contained in this document >> is legally privileged and confidential. If you are not the intended >> recipient or the person responsible for delivering it to the intended >> recipient, you are hereby advised that you are strictly prohibited from >> reading, using, copying or disseminating the contents of this document. >> Please inform the sender immediately or write to confidentiality at nbc.ca<mailto:confidentiality at nbc.ca> >> and delete this document immediately. >>

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