Define length(::SkipMissing)

Author: andyferris

NEWS.md

@@ -43,6 +43,7 @@ Standard library changes
 ------------------------
 * The `nextprod` function now accepts tuples and other array types for its first argument ([#35791]).
 * The function `isapprox(x,y)` now accepts the `norm` keyword argument also for numeric (i.e., non-array) arguments `x` and `y` ([#35883]).
+* `length` now supports `SkipMissing`-wrapped containers ([#35946]).
 
 #### LinearAlgebra
 

base/missing.jl

@@ -258,6 +258,13 @@ keys(itr::SkipMissing) =
     v === missing && throw(MissingException("the value at index $I is missing"))
     v
 end
+function length(itr::SkipMissing)
+    i = 0
+    for _ in itr
+        i += 1
+    end
+    return i
+end
 
 function show(io::IO, s::SkipMissing)
     print(io, "skipmissing(")

test/missing.jl

@@ -363,6 +363,7 @@ end
 @testset "skipmissing" begin
     x = skipmissing([1, 2, missing, 4])
     @test eltype(x) === Int
+    @test length(x) == 3
     @test collect(x) == [1, 2, 4]
     @test collect(x) isa Vector{Int}