More constructors for CFDateTime types

[BobPortmann]

The DateTime constructors that use DateFormat are not implemented for the CFDateTime types. For example,

julia> DateTime("19991205", "yyyymmdd")
1999-12-05T00:00:00

julia> DateTimeNoLeap("19991205", "yyyymmdd")
ERROR: MethodError: no method matching Int64(::String)
Closest candidates are:
  Int64(::Union{Bool, Int32, Int64, UInt32, UInt64, UInt8, Int128, Int16, Int8, UInt128, UInt16}) at boot.jl:717
  Int64(::Ptr) at boot.jl:727
  Int64(::Float32) at float.jl:697
  ...
Stacktrace:
 [1] DateTimeNoLeap(::String, ::String, ::Int64, ::Int64, ::Int64, ::Int64, ::Int64) at /Users/portmann/.julia/packages/NCDatasets/O31tb/src/time.jl:317 (repeats 2 times)
 [2] top-level scope at none:0

It would be handy to have these.

PS Great job on NCDatasets, I find it very useful!

[Alexander-Barth]

Thank you for your encouragements!
You probably know the constructors of the type DateTimeNoLeap(1999,12,5).

Parsing dates can quickly become very complicated; do you have an idea how function in julia's Dates module could be used for such parsing (so that one does not have to duplicate all the logic)?

[Alexander-Barth]

This should now work in the latest version of the master.
I took the approach from AstroTime:
https://github.com/JuliaAstro/AstroTime.jl/blob/master/src/AstroTime.jl

Can you test if it works for you as well?

[BobPortmann]

Yes, that works great. It is unfortunate that the functions in DateTime are not written to separate the parsing from the object creation so the parsing part can be easily reused. But the approach from AstroTime works.

Thanks much!

[Alexander-Barth]

Thanks you for your confirmation! I will make a new version soon.