BTW it is probably not a good idea to overwrite Properties (for example to get a defined store order). Especially since changes in the past already broke this. However the attached discussion shows that people do need insert-order and/or alphabetical ordered properties — maybe a more general solution would help (and also make sure that existing implementations which subtype Properties and overwrite entrySet() would continue to work? After all properties is/was not final.
https://stackoverflow.com/questions/17011108/how-can-i-write-java-properties-in-a-defined-order On a somewhat related note, I think if the Properties class is not deterministic, preserves order and comments, it’s maybe not a good file,creation APi for Maven anyway. What Plug-ins are affected for which operation? Gruss Bernd -- http://bernd.eckenfels.net ________________________________ Von: core-libs-dev <core-libs-dev-r...@openjdk.java.net> im Auftrag von Roger Riggs <roger.ri...@oracle.com> Gesendet: Monday, August 30, 2021 5:00:14 PM An: Jaikiran Pai <jai.forums2...@gmail.com>; core-libs-dev@openjdk.java.net <core-libs-dev@openjdk.java.net> Betreff: Re: Proposal: JDK-8231640 - (prop) Canonical property storage Hi Jaikiran, System properties, especially new ones, should be only settable on the command line and read once. It makes them visible to developers and avoids state-full dependencies and concurrency issues. Retiring system properties is quite difficult because there's no way to know if they are still being used or by whom. The technique using system properties to revert to previous behavior has been used when API changes are unavoidable and the impact on existing applications is not known. It isn't a good solution but does provide a workaround when an issue is discovered. Better to not introduce them in the first place. The use of SOURCE_DATE_EPOCH as proposed seems better than most, as its definition has a wider scope and longer expected life than most properties. Since SOURCE_DATE_EPOCH is an environment variable, not a system property, it will be less visible to developers, but is already read-once at first use of any environment variable as per System.getenv(). $.02, Roger On 8/28/21 12:45 AM, Jaikiran Pai wrote: > Hello Roger, > > On 28/08/21 12:16 am, Roger Riggs wrote: >> Hi, >> >> I'm finding the idea of removing the hardcoded timestamp and adding a >> property to restore compatibility >> strangely attractive. I don't think we've yet found a case where the >> timestamp was needed (but need to keep looking). >> (Adding a timestamp to the comment by the caller of store() is >> already possible) >> >> It will reveal where the timestamp is needed (via some kind of >> failure, though perhaps not a timely one) >> and includes a fallback mechanism when needed. >> >> It will generally cleanup up the behavior of an old API. >> The other approaches make new work for developers based on unclear >> requirements. > > So this is essentially the proposal 1d that I listed in one of my > mails, with the added advantage of allowing users to switch back to > the old behaviour with a system property setting. I hadn't considered > the system property approach to switch to old behaviour in my > proposals, so this is a very good input and I personally think the > most logical proposals so far. One question that however remains is, > how long (how many releases) do we support this new system property? > The --illegal-access option (although not a system property) seems to > be one such example where after a few releases, that option will no > longer be supported and won't play any role. Perhaps this system > property too will follow a similar lifetime? > > One other thing - I believe this new system property must be "set once > at launch time" kind of property, whose value can be set at launch > time and cannot be changed dynamically in the runtime. That would > provide consistency in how the Properties class behaves globally > within that runtime, instead of potentially behaving differently in > different parts of the code, depending on how the callers set/reset > the system property value before calling the "store(...)" APIs. > > -Jaikiran > >
