On Wed, Dec 21, 2011 at 8:41 PM, Jonathan M Davis <jmdavisProg@gmx.com>wrote:

> Okay. At the moment, the time point types in std.datetime have functions
> for
> converting to and from strings of standard formats but not custom formats,
> so
> functions for that need to be added. I've come up with a proposal for how
> they're going to work and would like some feedback on it.
>
> Originally, I was going to make them work like strftime and strptime,
> since it
> was my understanding that those functions were fairly standard among
> various
> programming languags. And it _does_ look like a variety of programming
> languages have something similar (Java, Ruby, Python, etc.), but the exact
> set
> of flags that they use is not standard, so there _isn't_ really a standard
> to
> follow, just similar functions across a variety of programming languages.
> And
> honestly, strftime and strptime aren't very good. They're fairly limited
> IMHO,
> and the choice of flags is fairly arbitrary, so it seems like a good idea
> to
> design our own, assuming that we can make something better.
>
> Stewart Gordon has a library that takes a different approach (
> http://pr.stewartsplace.org.uk/d/sutil/datetime_format.html ). It does
> away
> with % flags and uses maximul munch with each of the flags being name such
> that
> they don't overlap in a way that would make certain combinations of flags
> impossible. It then requires that characters which are not part of the
> flags be
> surrounded by single quotes. It's an interesting approach, but it isn't as
> flexible as it could be because of its use of maximul munch instead of %
> flags.
>
> So, I've come up with something new which tries to take the best of both.
> On
> the whole, I think that it's fairly straightforward, and the flags are
> generally recognizable and memorable (though there are a lot). It's also
> definitely extremely flexible (e.g. you can pass it functions to generate
> portions of the string if the existing flags don't get you quite what you
> need). But I'd like some feedback on it before I spend a lot of time on the
> implementation.
>
> This page has the docs for std.datetime with everything else but the
> proposed
> custom formatting functions for SysTime stripped out of it:
>
> http://jmdavis.github.com/d-programming-language.org/std_datetime.html
>
> So, what do you think?
>
> - Jonathan M Davis
>


I must admit, I was scared by the first couple of examples on that page.
 It looks like the the general use case is more approachable though.  I've
never been much of a fan of strftime as I have to look up the syntax every
time I use it (despite writing date scheduling software for a living) and
it's difficult to look up because most languages use that name but often
have variants to the flags (as you've said) and they all show up in a
google search.  That said, it works and I wouldn't be upset if D ended up
using it.

Personally, I don't know that phobos needs a highly advanced data formatting syntax built in. I kind of lean toward as simple of syntax as we can get that covers 99% of what people need and maybe have something like this offered as an third-party library for people who need its advanced features. I do think Stewart Gordon's approach is a good fit for this requirement.

In any case, I like how much thought you've put into this.

Regards,
Brad

On Thursday, December 22, 2011 20:13:26 Brad Anderson wrote:
> I must admit, I was scared by the first couple of examples on that page.
>  It looks like the the general use case is more approachable though.

I should probably pick different examples for the top. I went with the standard formats so that you could see how they were done, but they're pretty ugly, since they have to be very exact. The formats are much nicer when you don't have to worry about stuff like putting a + in front of A.D. dates only when the year is 10,000 or greater.

- Jonathan M Davis