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Recommend using package-specific prefix with arrowname #541

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Recommend using package-specific prefix with arrowname #541

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9 changes: 5 additions & 4 deletions docs/src/manual.md
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Original file line number Diff line number Diff line change
Expand Up @@ -109,11 +109,12 @@ end

# overload interface method for custom type Person; return a symbol as the "name"
# this instructs Arrow.write what "label" to include with a column with this custom type
ArrowTypes.arrowname(::Type{Person}) = :Person
# overload JuliaType on `Val{:Person}`, which is like a dispatchable string
const NAME = Symbol("JuliaLang.MyPackage.Person")
ArrowTypes.arrowname(::Type{Person}) = NAME
# overload JuliaType on `Val{NAME}`, which is like a dispatchable string
# return our custom *type* Person; this enables Arrow.Table to know how the "label"
# on a custom column should be mapped to a Julia type and deserialized
ArrowTypes.JuliaType(::Val{:Person}) = Person
ArrowTypes.JuliaType(::Val{NAME}) = Person

table = (col1=[Person(1, "Bob"), Person(2, "Jane")],)
io = IOBuffer()
Expand Down Expand Up @@ -160,7 +161,7 @@ using Intervals
table = (col = [
Interval{Closed,Unbounded}(1,nothing),
],)
const NAME = Symbol("JuliaLang.Interval")
const NAME = Symbol("JuliaLang.Intervals.Interval")
ArrowTypes.arrowname(::Type{Interval{T, L, R}}) where {T, L, R} = NAME
const LOOKUP = Dict(
"Closed" => Closed,
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6 changes: 3 additions & 3 deletions src/ArrowTypes/src/ArrowTypes.jl
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Expand Up @@ -100,9 +100,9 @@ toarrow(x) = x
ArrowTypes.arrowname(T) = Symbol(name)

Interface method to define the logical type "label" for a custom Julia type `T`. Names will be global for an entire arrow dataset,
and conventionally, custom types will just use their type name along with a Julia-specific prefix; for example, for a custom type
`Foo`, I would define `ArrowTypes.arrowname(::Type{Foo}) = Symbol("JuliaLang.Foo")`. This ensures other language implementations
won't get confused and are safe to ignore the logical type label.
and conventionally, custom types will just use their type name along with a Julia- and package-specific prefix; for example,
for a custom type `Foo`, I would define `ArrowTypes.arrowname(::Type{Foo}) = Symbol("JuliaLang.MyPackage.Foo")`.
This ensures other language implementations won't get confused and are safe to ignore the logical type label.
When arrow stores non-native data, it must still be _stored_ as a native data type, but can have type metadata tied to the data that
labels the original _logical_ type it originated from. This enables the conversion of native data back to the logical type when
deserializing, as long as the deserializer has the same definitions when the data was serialized. Namely, the current Julia
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