Extend/Assign DateTime

General
1

I have a pair of setter/getter methods I wrote for Date to extend it to deal with ISO8601 times in strings. The setter extends Date and assigns the value of the passed ISO8601 string to the passed-in date object, which worked fine when it was possible to set the fields… I’ve rewritten it for DateTime, but how do I effect the “assigns” part? Assigning a new DateTime constructed from the extracted date/time elements to the passed-in “extends” variable doesn’t work. I guess I could construct a new DateTime object with the value I want, .ToString it, and then .FromString it back to the original assigns variable, but that seems somewhat roundabout. Is there a right way to do this?

2

Could you post some code showing what you’d like to be able to do?

3

I’d like to extend DateTime with a computed .ISO8601 property implemented with a getter/setter pair. The getter returns the DateTime’s value in ISO8601 format (optionally takes a format spec), while the setter sets the DateTime’s value from an ISO8601 date string.

The method definitions look like:
ISO8601(extends d as datetime, optional fmt as string = "YMDhmsZ-")
ISO8601(extends d as datetime, assigns dateval as string)

You’d use them like this:

var d as DateTime
...
someISO8601String as string = d.ISO8601   'get the DateTime value as an ISO8601
...
d.ISO8601 = someISO8601String    'set the DateTime from an ISO8601

The setter implementation parses the 8601 string, getting all of the elements of a DateTime and then needs to end by assigning them to the DateTime. I’ve tried

d = new DateTime(...)

and

ddd = new datetime(yy,mm,dd,floor(hh),floor(mi),floor(ss),ns,tz)

d = datetime.FromString(ddd.SQLDateTime,nil,tz)

Neither seems to “stick” on the return (I assume because we’re really making a reference to a new DateTime so “assigning” it to the reference in the calling context doesn’t actually happen).

Can work around by just making a regular method to create a DateTime from a string.

Should add this is an API2 conversion from the same methods implemented for Date, which allowed you to assign the individual properties of the date.

4

Right. So DateTime (unlike Date) really is immutable. That means that you can’t change them in place.

That said, you could create your own wrapper for DateTime which stores a DateTime under the hood, returns the DateTime with Operator_Convert and then add your methods to that class. It’d be a bit of work to add all of the methods, but it could be generic enough to share among projects.

5

Greg, thanks for confirming and offering an option for a solution, which I’ll mark here for others to find. In my case, I converted it to a standalone function that returns a new DateTime from an ISO8601 string.

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