Move ConstructionBase dependency to an extension on 1.9+

The dependency on ConstructionBase serves to provide a few convenience
methods for users of packages like Accessors; it doesn't provide any
functionality used directly by Legolas. This makes it a perfect
candidate for a package extension.

Package extensions are new in Julia 1.9, and Legolas currently supports
Julia 1.6. That means that we can't fully remove ConstructionBase as a
direct dependency yet, but we can restructure things to make that as
easy as possible once we drop support for earlier Julia versions.

Project.toml

@@ -10,6 +10,12 @@ ConstructionBase = "187b0558-2788-49d3-abe0-74a17ed4e7c9"
 Tables = "bd369af6-aec1-5ad0-b16a-f7cc5008161c"
 UUIDs = "cf7118a7-6976-5b1a-9a39-7adc72f591a4"
 
+[weakdeps]
+ConstructionBase = "187b0558-2788-49d3-abe0-74a17ed4e7c9"
+
+[extensions]
+LegolasConstructionBaseExt = "ConstructionBase"
+
 [compat]
 Accessors = "0.1"
 Aqua = "0.6"

ext/LegolasConstructionBaseExt.jl

@@ -0,0 +1,32 @@
+module LegolasConstructionBaseExt
+
+using ConstructionBase
+using Legolas
+
+using Legolas: AbstractRecord
+
+# We need a bit of extra work to integrate with ConstructionBase for pre-1.7 due
+# to the overload of `propertynames(::Tables.AbstractRow)`. We could overload
+# `check_properties_are_fields` but that's not part of the public API, so this
+# is safer.
+if VERSION < v"1.7"
+    ConstructionBase.getproperties(r::AbstractRecord) = NamedTuple(r)
+
+    # This is largely copy-paste from `ConstructionBase.setproperties_object`:
+    # https://github.com/JuliaObjects/ConstructionBase.jl/blob/cd24e541fd90ab54d2ee12ddd6ccd229be9a5f1e/src/ConstructionBase.jl#L211-L218
+    function ConstructionBase.setproperties(r::R, patch::NamedTuple) where {R<:AbstractRecord}
+        nt = getproperties(r)
+        nt_new = merge(nt, patch)
+        check_patch_properties_exist(nt_new, nt, r, patch)
+        args = Tuple(nt_new)  # old Julia inference prefers if we wrap in `Tuple`
+        return constructorof(R)(args...)
+    end
+end
+
+function ConstructionBase.constructorof(::Type{<:R}) where {R<:AbstractRecord}
+    nt = NamedTuple{fieldnames(R)}
+    T = Base.typename(R).wrapper
+    return (args...) -> T(nt(args))
+end
+
+end  # module

src/Legolas.jl

@@ -1,7 +1,6 @@
 module Legolas
 
 using Tables, Arrow, UUIDs
-using ConstructionBase: ConstructionBase
 
 const LEGOLAS_SCHEMA_QUALIFIED_METADATA_KEY = "legolas_schema_qualified"
 
@@ -10,4 +9,11 @@ include("schemas.jl")
 include("tables.jl")
 include("record_merge.jl")
 
+# TODO: Once we require Julia 1.9 or later at a minimum, we can remove this as well as
+# all entries in the Project.toml `[deps]` section that are also listed in `[weakdeps]`.
+if !isdefined(Base, :get_extension)
+    include(joinpath(dirname(@__DIR__), "ext", "LegolasConstructionBaseExt.jl"))
+    using .LegolasConstructionBaseExt
+end
+
 end # module

src/schemas.jl

@@ -345,24 +345,6 @@ abstract type AbstractRecord <: Tables.AbstractRow end
 @inline Tables.columnnames(r::AbstractRecord) = fieldnames(typeof(r))
 @inline Tables.schema(::AbstractVector{R}) where {R<:AbstractRecord} = Tables.Schema(fieldnames(R), fieldtypes(R))
 
-# we need a bit of extra work to integrate with ConstructionBase for pre-1.7 due
-# to the overload of `propertynames(::Tables.AbstractRow)`
-#
-# we _could_ overload `check_properties_are_fields` but that's no part of the
-# public API so this is safer
-@static if VERSION < v"1.7"
-    ConstructionBase.getproperties(r::AbstractRecord) = NamedTuple(r)
-    # largely copy-paste from ConstructionBase.setproperties_object:
-    # https://github.com/JuliaObjects/ConstructionBase.jl/blob/cd24e541fd90ab54d2ee12ddd6ccd229be9a5f1e/src/ConstructionBase.jl#L211-L218
-    function ConstructionBase.setproperties(r::R, patch::NamedTuple) where {R <: AbstractRecord}
-        nt = ConstructionBase.getproperties(r)
-        nt_new = merge(nt, patch)
-        ConstructionBase.check_patch_properties_exist(nt_new, nt, r, patch)
-        args = Tuple(nt_new) # old julia inference prefers if we wrap in Tuple
-        return ConstructionBase.constructorof(R)(args...)
-    end
-end
-
 """
     Legolas.schema_version_from_record(record::Legolas.AbstractRecord)
 
@@ -628,10 +610,6 @@ function _generate_record_type_definitions(schema_version::SchemaVersion, record
     kwargs_from_row = [Expr(:kw, n, :(get(row, $(Base.Meta.quot(n)), missing))) for n in keys(record_fields)]
     outer_constructor_definitions = quote
         $R(row) = $R(; $(kwargs_from_row...))
-        function $ConstructionBase.constructorof(::Type{<:$R})
-            nt = NamedTuple{$((:($k) for k in keys(record_fields))..., )}
-            (args...) -> $R(nt(args))
-        end
     end
     if isempty(type_param_defs)
         inner_constructor_definitions = quote