It sounds like you're pretty set against making separate impl traits and would prefer just putting things directly on TimeHelper. I'm OK with that, but I would really like to add a lift-joda module that contains the JodaHelpers, JodaTimeFormats and JodaTimeHelpers traits as I would like to use them. I should be able to delegate a good chunk of the methods to TimeHelpers.jt*, so there shouldn't be any *redundant* code. Is that a reasonable compromise?
Derek On Tue, Oct 20, 2009 at 11:35 PM, Derek Chen-Becker <dchenbec...@gmail.com>wrote: > I agree that the goal isn't to remove java.util.Date. For trivial time > handling it works just fine. What I'm trying to achieve here is a way to > make Joda Time be the default impl while leaving the user a choice. By using > separate traits instead of different names on the same trait, we achieve a > few things: > > 1. A consistent API for both java.util and Joda Time in terms of method > names. As Naftoli pointed out, people expect naming of functions consistent > with what they do and having two different "now"s on the same trait is > going > to look a little strange to people, I think. > 2. A clean *optional* usage of Joda Time. If we put code that utilizes > Joda Time directly into TimeHelpers then it's not an optional dependency. > Making a separate trait means that if someone doesn't use the Joda Time > trait then they don't need to have the Joda Time jar in their classpath and > they never know that it's not there. > 3. A relatively simple code change path to move from java.util to Joda > Time by simply changing imports. > > Your assertion that Date is a simple wrapper for a Long timestamp is pretty > accurate, but really Joda Time's DateTime is a superset of *Calendar*, not > Date. Just look at what we had to do with CalendarExtension to get some > simple date manipulation functions, where those same methods are already > defined on DateTime. The vast majority of Joda Time's classes are immutable, > and the mutators return new instances instead of modifying the current > instance. TimeSpan's current handling of duration addition doesn't cope with > DST, which I'm sure will show up as a bug in someone's code if it hasn't > already. Having done a fair amount of java.util.Date handling and then > moving to Joda Time, I find it hard to call the difference between the two > APIs "marginal". In any case, I still feel that my proposal makes Joda Time > available in a nicer way while leaving existing code completely untouched > (by introducing a JodaHelpers trait that mirrors Helpers). > > Derek > > > On Tue, Oct 20, 2009 at 9:25 PM, David Pollak < > feeder.of.the.be...@gmail.com> wrote: > >> >> >> On Tue, Oct 20, 2009 at 6:56 PM, Naftoli Gugenheim >> <naftoli...@gmail.com>wrote: >> >>> >>> I agree with this. >>> My understanding is that the goal is that Lift should use Joda for its >>> time functions rather than java.util. >> >> >> This is not the goal. The goal is to make JodeTime available. There is >> no reason to remove support for java.util.Date. None. >> >> JodaTime offers some advantages, but there's no reason, none, nada, to >> *remove* support for java.util.Date. >> >> I'm cool with different names (not jtNow, but choose something else). >> >> But I view removal of support for java.util.Date as gratuitous. Sure, if >> we were to make the clean-slate decision today, I'd opt for primary support >> of JodaTime and secondary support for java.util.Date. But we're making a >> decision based on legacy. We're not going to cut off java.util.Date just >> because something marginally better (and I'm not being facetious here... at >> the bottom, these are just wrappers for number of milliseconds since Jan 1, >> 1970). >> >> >>> If the Joda methods have different and longer names, then it's existing >>> side by side with the java.util implementation, not replacing it. >>> To many people, it is important that methods etc. should be named >>> properly and aesthetically. It's not pleasant to use names like "jtNow" in >>> your code when that is the method that gets used normally. Sure, if 'now' >>> was the usual method and a 'jtNow' method was called in special >>> circumstances, it's an understandable name. But names that are used in >>> ordinary circumstances should have straightforward names. >>> (Names should be concise expressions of what they represent. This aids in >>> memorization and code readability.) >>> Also, it will be impossible to deprecate the java.util implementation and >>> have a clean API instead. If we use separate traits with the same method >>> names, then we will be able to. >>> >>> >>> ------------------------------------- >>> Derek Chen-Becker<dchenbec...@gmail.com> wrote: >>> >>> On Tue, Oct 20, 2009 at 4:59 PM, David Pollak < >>> feeder.of.the.be...@gmail.com >>> > wrote: >>> >>> > What I checked in allows you to use JodaTime just as easily (well with >>> 2 >>> > extra characters in a few method names) as java.util.Date. How is >>> anything >>> > more "default" than that? >>> > >>> >>> My primary concern with this approach is that it makes changing between >>> the >>> two implementations something that requires a global search and replace >>> on >>> one or more method names, whereas having two different implementation >>> traits >>> means that generally I should be able to just change the import and the >>> code >>> will work. A secondary (minor) concern is that having method names >>> reflect >>> the underlying implementation details goes against my aesthetics. >>> >>> >>> > It's an interesting difference between an OO vs. non-OO. In the >>> > implementation I created, there choice of one or the other is made >>> based on >>> > singleton methods invoked. This allows mixing both in the same code >>> simply >>> > by invoking now or jtNow. >>> > >>> >>> I would argue that it's not a common case where you would want to use >>> both >>> libraries, particularly when Joda's DateTime has an explicit toDate on it >>> that returns a java.util.Date. There are similar methods to return >>> Calendar >>> and TimeZone instances as needed. These are simple methods to use >>> directly, >>> or it's easy to create a view that handles this automatically. >>> >>> I'm unclear why this is not possible. We can add a DSL for manipulating >>> > JodaTime without breaking anything we have. The TimeSpan class simply >>> gets >>> > enhanced to deal with additional stuff and maybe uses JodaTime under >>> the >>> > covers. >>> > >>> >>> The underpinning of the current DSL is the TimeSpan class. Joda Time >>> already >>> has a time interval class corresponding to TimeSpan called Duration, but >>> the >>> more proper class to use is actually Period. Period is premised not on ms >>> duration but rather on field deltas, which allows it to properly handle >>> DST. >>> Modifying the current DSL to work for Duration and Period via TimeSpan is >>> just going to end up with a lot of redundant code, when a Joda-only DSL >>> would be cleaner and more in line with how you would want to use Joda >>> Time. >>> >>> >>> > They have that now with the implementation I did on your branch. >>> > >>> >>> Like I said before, I have a strong preference for the OO approach and >>> being >>> able to change impls by changing the import rather than having to change >>> methods all over the place. If you really feel strongly that we can't >>> have a >>> separate trait in Lift, I can just create a different artifact in my own >>> repo that tracks Lift and create the JodaHelpers, JodaTimeFormats and >>> JodaTimeHelpers traits there. >>> >>> Cheers, >>> >>> Derek >>> >>> >>> >>> >>> >> >> >> -- >> Lift, the simply functional web framework http://liftweb.net >> Beginning Scala http://www.apress.com/book/view/1430219890 >> Follow me: http://twitter.com/dpp >> Surf the harmonics >> >> >> >> > --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "Lift" group. To post to this group, send email to liftweb@googlegroups.com To unsubscribe from this group, send email to liftweb+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/liftweb?hl=en -~----------~----~----~----~------~----~------~--~---
