[phobos] datetime review

[Steve Schveighoffer]

OK, read through all the datetime messages now, responding to these points 
below:



----- Original Message ----
> From: Jonathan M Davis <jmdavisProg at gmx.com>
> To: phobos at puremagic.com
> Sent: Tue, October 12, 2010 1:58:15 PM
> Subject: Re: [phobos] datetime review
> 
> On Tuesday, October 12, 2010 07:21:07 Andrei Alexandrescu wrote:
> >  Speaking of all this, Jonathan, what's your plan right now? There's been
> >  some points raised here and there by people, you replied "this is a good
> >  suggestion but there are cons as well", so I'm not sure whether you plan
> >  to keep the submission as is or operate changes to it. In the latter
> >  case, I'm unclear on what changes you have decided to make.
> > 
> > One  other thing - it might be useful to take this entire review process
> > to  digitalmars.D. Is everyone comfortable with that?
> 
> I have been making  various of the suggested changes, and I hope to have an 
> updated version with  most or all of them by this weekend at the latest, but 
>I'm 
>
> not at home at  the moment with the updated code, so I can't say for sure what 

> all the  changes are that I've made or am making, though I'll give a list when 
>I 
>
> post  the new code.
> 
> I did decide to make changes to reduce the durations to  just Duration (which 
>is 
>
> basically HNSecDuration) and TickDuration and have  removed most of the 
>addXXX() 
>
> functions. I'm not entirely happy with result  since dealing with years and 
> months is definitely more awkward in some  cases, but I think that the places 
> where it's a problem are relatively  limited and that it's likely going to be 
> easier for the average  programmer.

I'm interested to see this.  I originally thought having simply a duration in 
number of hnsecs would be sufficient, but I didn't really hate the way you had 
the different duration types.  It certainly was a novel idea.  The only awkward 
part is when you'd expect normalization.

FWIW, I think ignoring months/years except for where they are needed is a solid 
way of doing it.  In Tango, the calendar class had an addMonths(Time t, int 
months) which was sufficient for almost all uses. 


IMO, all you lose here is syntax:  not being able to simply do a + b.

> 
> I'm currently working on converting TUnit over to use strings  as you 
>suggested, 
>
> and assuming that nothing particularly wrong with that  pops up, I'll be going 

> with that. Certainly, having to type stuff like  TUnit.day seems pretty ugly, 
> though I did manage to limite the number of  places where TUnit needed to be 
>used 
>
> directly by the users of  datetime.

One of the issues of using enums to parameterize templates is:

foo(TUnit tu)(long xyz) {...}

requires instantiating like:

foo!(TUnit.seconds)(123);

But can't the compiler just assume you are passing a TUnit value?  i.e. we could 
make this the equivalent of the string version (with the added bonus of not 
requiring silly constraints) if you could call foo like:

foo!seconds(123);

Has this been proposed and rejected before?  I can't imagine I'm the first to 
bring this up...

> I think that I'm applying most of your suggestions (and  possibly some of the 
> suggestions of others), but again, I'd have to look at  what I've got at home 
>to 
>
> remember exactly what changes I've made thus far. I  have no problem with 
>taking 
>
> the review process to digitalmars.D,  particularly since there never seems to 
>be 
>
> many people beyond the Phobos  devs themselves who post much on the Phobos 
>list. 
>
> So, I'll post it there as  soon as it's ready.

Looking forward to it.

-Steve