Deprecate parse(::AbstractString, ::DateFormat)

[omus]

Properly deprecates the Dates.parse(::AbstractString, ::DateFormat) -> Array{Period} function and replaces it with parse(::Type{Array{Period}}, ::AbstractString, ::DateFormat) -> Array{Period}. Note that the replacement slightly differs from the original function by returning the periods in the order of the DateFormat tokens and in period sorted order.

Fixes #20876

[omus]

I possibly could have reworked the original tryparse_internal instead of making a new method but it seemed safest to avoid refactoring code this close to release.

[tkelman]

there's no separate branch yet

[tkelman]

wrap long lines

[shashi]

It seems this is pretty much doing the same thing as

julia/base/dates/parse.jl

Line 3 in 67189c9

@generated function tryparse_internal{T<:TimeType, S, F}(::Type{T}, str::AbstractString, df::DateFormat{S, F}, raise::Bool=false)

? except is 1) not reordering the output 2) not wrapping the numbers in Period types 3) returning an Array instead of a tuple. Is being able to return values unsorted really useful? The deprecation suggests doing the sort anyway.

This new method could just be

function Base.parse{T<:Array{Period}}(::Type{T}, str::AbstractString, df::DateFormat)
     Period[get(tryparse_internal(DateTime, str, df, true))...]
end

if sorting the periods automatically is not a problem.

returning an array in a function like this seems like a performance trap, we should probably consider just returning that tuple.

[omus]

@shashi additionally the revised function is only returning the periods specified in the format:

julia> Base.Dates.tryparse_internal(DateTime, "Apr 1, 24:00", dateformat"uuu dd, HH:MM", true)
Nullable{NTuple{7,Int64}}((1, 4, 1, 24, 0, 0, 0))

julia> Base.Dates.parse(Array{Dates.Period}, "Apr 1, 24:00", dateformat"uuu dd, HH:MM")
4-element Array{Base.Dates.Period,1}:
 4 months 
 1 day    
 24 hours 
 0 minutes

This is the reason I ended up returning an Array{Period} instead of a tuple.

Is being able to return values unsorted really useful? The deprecation suggests doing the sort anyway.

I consider that the old behaviour of always returning the periods in reverse sorted order was unnecessary and made it impossible to get the values in the order of the format. The deprecation suggests using a sort only so that deprecated code is 100% backwards compatible.

[StefanKarpinski]

Is this superseded by your newer PR or should we go ahead with this?

[omus]

Is this superseded by your newer PR or should we go ahead with this?

This PR is superseded by #20952