Using `repr` on `DateTime` shows pretty-printed version

[omus]

According to the docstring for repr:

Note that repr(x) is usually similar to how the value of x would be entered in Julia

Unfortunately this is not the behaviour of Date and DateTime:

julia> using Dates

julia> x = Date(2018)
2018-01-01

julia> repr(x)
"2018-01-01"

julia> y = DateTime(2018)
2018-01-01T00:00:00

julia> repr(y)
"2018-01-01T00:00:00"

[omus]

cc: @quinnj

[omus]

I'll note that I thought of this based upon a comment @JeffBezanson made on discourse.

[StefanKarpinski]

Yeah, this is not the desired behavior—it should print the way you input it.

[quinnj]

Yeah, looks like TimeTypes are just hitting the default path which calls show. Should be an easy up-for-grabs if anyone wants to take a crack at it.

[p-murli]

Hey, I'd like to contribute to this if it is open. I'm a beginner, so could you also guide me on how to get started with this issue?

[omus]

Hi @p-murli. To get started you should take a look at the code that the Dates stdlib uses for show and string. You can do that easily by running using Dates; @edit show(stdout, today()). I think what we want is to have the current show methods be print methods instead and add some new show methods. The end result should look like:

julia> using Dates

julia> d = Date(2018)
2018-01-01

julia> print(d)
2018-01-01
julia> string(d)
"2018-01-01"

julia> show(d)
Date(2018, 1, 1)

julia> repr(d)
"Date(2018, 1, 1)"

I'll mention that the repr method calls show and string calls print so you should only need to define Base.show(io::IO, ...) and Base.print(io::IO, ...) methods.

[sam0410]

Hi @omus, Please tell me if I am missing something. But aren't the following two outputs contradictory ?
julia> d = Date(2018)
2018-01-01
and
julia> show(d)
Date(2018, 1, 1)

[JeffBezanson]

REPL printing calls display, which calls the 3-argument form of show (including a MIME type). So they can be different, e.g.

julia> [1,2]
2-element Array{Int64,1}:
 1
 2

julia> show([1,2])
[1, 2]

[sam0410]

Thanks @JeffBezanson .
I added a PR. Please review.