Add getindex methods for NamedTuple

NEWS.md

@@ -45,6 +45,7 @@ Standard library changes
 * `iseven` and `isodd` functions now support non-`Integer` numeric types ([#38976]).
 * `escape_string` can now receive a collection of characters in the keyword
   `keep` that are to be kept as they are. ([#38597]).
+* `getindex` can now be used on `NamedTuple`s with multiple values ([#38878])
 
 #### Package Manager
 

base/namedtuple.jl

@@ -9,9 +9,9 @@ tuple-like collection of values, where each entry has a unique name, represented
 can be modified in place after construction.
 
 Accessing the value associated with a name in a named tuple can be done using field
-access syntax, e.g. `x.a`, or using [`getindex`](@ref), e.g. `x[:a]`. A tuple of the
-names can be obtained using [`keys`](@ref), and a tuple of the values can be obtained
-using [`values`](@ref).
+access syntax, e.g. `x.a`, or using [`getindex`](@ref), e.g. `x[:a]` or `x[(:a, :b)]`.
+A tuple of the names can be obtained using [`keys`](@ref), and a tuple of the values
+can be obtained using [`values`](@ref).
 
 !!! note
     Iteration over `NamedTuple`s produces the *values* without the names. (See example
@@ -30,6 +30,9 @@ julia> x.a
 julia> x[:a]
 1
 
+julia> x[(:a,)]
+(a = 1,)
+
 julia> keys(x)
 (:a, :b)
 
@@ -76,6 +79,9 @@ julia> (; t.x)
 
 !!! compat "Julia 1.5"
     Implicit names from identifiers and dot expressions are available as of Julia 1.5.
+
+!!! compat "Julia 1.7"
+    Use of `getindex` methods with multiple `Symbol`s is available as of Julia 1.7.
 """
 Core.NamedTuple
 
@@ -116,6 +122,8 @@ firstindex(t::NamedTuple) = 1
 lastindex(t::NamedTuple) = nfields(t)
 getindex(t::NamedTuple, i::Int) = getfield(t, i)
 getindex(t::NamedTuple, i::Symbol) = getfield(t, i)
+@inline getindex(t::NamedTuple, idxs::Tuple{Vararg{Symbol}}) = NamedTuple{idxs}(t)
+@inline getindex(t::NamedTuple, idxs::AbstractVector{Symbol}) = NamedTuple{Tuple(idxs)}(t)
 indexed_iterate(t::NamedTuple, i::Int, state=1) = (getfield(t, i), i+1)
 isempty(::NamedTuple{()}) = true
 isempty(::NamedTuple) = false

test/namedtuple.jl

@@ -21,9 +21,20 @@
 @test (a=3,)[:a] == 3
 @test (x=4, y=5, z=6).y == 5
 @test (x=4, y=5, z=6).z == 6
+@test (x=4, y=5, z=6)[(:x, :y)] == (x=4, y=5)
+@test (x=4, y=5, z=6)[(:x,)] == (x=4,)
+@test (x=4, y=5, z=6)[[:x, :y]] == (x=4, y=5)
+@test (x=4, y=5, z=6)[[:x]] == (x=4,)
+@test (x=4, y=5, z=6)[()] == NamedTuple()
+@test NamedTuple()[()] == NamedTuple()
 @test_throws ErrorException (x=4, y=5, z=6).a
 @test_throws BoundsError (a=2,)[0]
 @test_throws BoundsError (a=2,)[2]
+@test_throws ErrorException (x=4, y=5, z=6)[(:a,)]
+@test_throws ErrorException (x=4, y=5, z=6)[(:x, :a)]
+@test_throws ErrorException (x=4, y=5, z=6)[[:a]]
+@test_throws ErrorException (x=4, y=5, z=6)[[:x, :a]]
+@test_throws ErrorException (x=4, y=5, z=6)[(:x, :x)]
 
 @test length(NamedTuple()) == 0
 @test length((a=1,)) == 1