JuliaCollections/OrderedCollections.jl

OrderedDict should rehash on deepcopy (like Dict does)

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#115 opened on Apr 20, 2024

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good first issue

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Description

Compare:

julia> mutable struct ConstIdentity
       end

julia> dict = OrderedDict{ConstIdentity, Int64}()
Dict{ConstIdentity, Int64}()

julia> dict[ConstIdentity()] = 1
1

julia> dict[ConstIdentity()] = 2
2

julia> all(haskey.((dict,), keys(dict)))
true

julia> dict2 = deepcopy(dict)
OrderedDict{ConstIdentity, Int64} with 2 entries:
  ConstIdentity() => 1
  ConstIdentity() => 2

julia> all(haskey.((dict2,), keys(dict2)))
false

vs Dict:

julia> mutable struct ConstIdentity
       end

julia> dict = Dict{ConstIdentity, Int64}()
Dict{ConstIdentity, Int64}()

julia> dict[ConstIdentity()] = 1
1

julia> dict[ConstIdentity()] = 2
2

julia> all(haskey.((dict,), keys(dict)))
true

julia> dict2 = deepcopy(dict)
Dict{ConstIdentity, Int64} with 2 entries:
  ConstIdentity() => 1
  ConstIdentity() => 2

julia> all(haskey.((dict2,), keys(dict2)))
true

We need to override deepcopy_internal to rehash like base does: https://github.com/JuliaLang/julia/blob/13155226e11fa025be5d4d3033d25c1091b35887/base/deepcopy.jl#L141-L156

Contributor guide

Research direction
Look at the base deepcopy internal implementation for Dict and implement similar rehashing for OrderedDict in deepcopy internal.
Tech stack
julia
Domain
backend
Issue type
Bug
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
2
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
1-3 hours
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
Active
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
Clear
Prerequisites
Julia
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
70