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digitalmars.D.learn - Parsing a date string into a std.datetime.datetime

reply "Colin" <grogan.colin gmail.com> writes:
Hi,

I'm looking for an easy way to parse a dates into a datetime 
object.

Most of my dates will be of the form:
mmm dd, yyyy HH:MM AM|PM

So like: "May 30, 2014 12:12 PM"

I can easily write a regex or whatever to pull these out of that 
one format, but it's not guaranteed they'll all be in the one 
format and I may have to deal with others.

Is there a helper function that I'm missing that can parse these 
dates? Maybe something similar to pythons dateutil.parser [1] ?

If not maybe adding this function to std.datetime would be a good 
project to undertake for myself...

[1] - https://labix.org/python-dateutil
Oct 23 2014
parent reply "Jonathan M Davis" <jmdavisProg gmx.com> writes:
On Thursday, 23 October 2014 at 11:13:26 UTC, Colin wrote:

 Hi,

 I'm looking for an easy way to parse a dates into a datetime 
 object.

 Most of my dates will be of the form:
 mmm dd, yyyy HH:MM AM|PM

 So like: "May 30, 2014 12:12 PM"

 I can easily write a regex or whatever to pull these out of 
 that one format, but it's not guaranteed they'll all be in the 
 one format and I may have to deal with others.

 Is there a helper function that I'm missing that can parse 
 these dates? Maybe something similar to pythons dateutil.parser 
 [1] ?

 If not maybe adding this function to std.datetime would be a 
 good project to undertake for myself...

 [1] - https://labix.org/python-dateutil


std.datetime supports the ISO formats but, it does not currently 
support generating or parsing custom strings for dates or times. 
It's on my todo list (probably after splitting std.datetime into 
a package), but I don't know exactly when I'm going to get to it. 
The first step will be figuring out what the format strings will 
look like, since what languages like C do is a complete mess. I 
had a proposal on it that was discussed a while ago, but it was 
too complicated. It'll probably end up being something closer to 
this http://pr.stewartsplace.org.uk/d/sutil/datetime_format.html 
though I'm afraid that that approach as it's presented might not 
be flexible enough. I'll probably need to do something like add a 
templated function that returns a custom struct with the values 
that you want so that you can get them effeiently to build the 
string yourself in the cases where you need to do something wacky 
enough that the normal custom string formatting functions aren't 
flexible enough. Then leaving the normal custom string format 
generating and parsing functions simpler works better.

In any case, I intend to get to it, but I've been dreadfully slow 
about it. It's the number one thing missing from std.datetime. 
I'd prefer to do it myself, but there's certainly no reason why 
someone else can't do it if they really want to.

- Jonathan M Davis
Oct 23 2014
parent "Colin" <grogan.colin gmail.com> writes:
On Thursday, 23 October 2014 at 21:17:23 UTC, Jonathan M Davis 
wrote:

 On Thursday, 23 October 2014 at 11:13:26 UTC, Colin wrote:

 Hi,

 I'm looking for an easy way to parse a dates into a datetime 
 object.

 Most of my dates will be of the form:
 mmm dd, yyyy HH:MM AM|PM

 So like: "May 30, 2014 12:12 PM"

 I can easily write a regex or whatever to pull these out of 
 that one format, but it's not guaranteed they'll all be in the 
 one format and I may have to deal with others.

 Is there a helper function that I'm missing that can parse 
 these dates? Maybe something similar to pythons 
 dateutil.parser [1] ?

 If not maybe adding this function to std.datetime would be a 
 good project to undertake for myself...

 [1] - https://labix.org/python-dateutil


 std.datetime supports the ISO formats but, it does not 
 currently support generating or parsing custom strings for 
 dates or times. It's on my todo list (probably after splitting 
 std.datetime into a package), but I don't know exactly when I'm 
 going to get to it. The first step will be figuring out what 
 the format strings will look like, since what languages like C 
 do is a complete mess. I had a proposal on it that was 
 discussed a while ago, but it was too complicated. It'll 
 probably end up being something closer to this 
 http://pr.stewartsplace.org.uk/d/sutil/datetime_format.html 
 though I'm afraid that that approach as it's presented might 
 not be flexible enough. I'll probably need to do something like 
 add a templated function that returns a custom struct with the 
 values that you want so that you can get them effeiently to 
 build the string yourself in the cases where you need to do 
 something wacky enough that the normal custom string formatting 
 functions aren't flexible enough. Then leaving the normal 
 custom string format generating and parsing functions simpler 
 works better.

 In any case, I intend to get to it, but I've been dreadfully 
 slow about it. It's the number one thing missing from 
 std.datetime. I'd prefer to do it myself, but there's certainly 
 no reason why someone else can't do it if they really want to.

 - Jonathan M Davis


Ok, thanks for the informative reply Jonathan.

For now I'll go with parsing the few types of dates I may need, 
and maybe port over in the future when you get to it.

Cheers!
Oct 24 2014