Broadcast AbstractRNG like a scalar (#33213)

* Broadcast AbstractRNG like a scalar * Add PR link to NEWS
JuliaLang · Sep 23, 2019 · 187ee96 · 187ee96
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diff --git a/NEWS.md b/NEWS.md
@@ -46,12 +46,17 @@ Standard library changes
 
 * `dot` now admits a 3-argument method `dot(x, A, y)` to compute generalized dot products `dot(x, A*y)`, but without computing and storing the intermediate result `A*y` ([#32739]).
 
-#### SparseArrays
+#### Random
+
+
+* `AbstractRNG`s now behave like scalars when used in broadcasting ([#33213]).
 
 * Products involving sparse arrays now allow more general sparse `eltype`s, such as `StaticArrays` ([#33205])
 
-#### Dates
 
+#### SparseArrays
+
+#### Dates
 
 #### Statistics
 

diff --git a/stdlib/Random/src/Random.jl b/stdlib/Random/src/Random.jl
@@ -40,6 +40,8 @@ Supertype for random number generators such as [`MersenneTwister`](@ref) and [`R
 """
 abstract type AbstractRNG end
 
+Base.broadcastable(x::AbstractRNG) = Ref(x)
+
 gentype(::Type{X}) where {X} = eltype(X)
 gentype(x) = gentype(typeof(x))
 

diff --git a/stdlib/Random/test/runtests.jl b/stdlib/Random/test/runtests.jl
@@ -774,3 +774,7 @@ end
     @test Sampler(GLOBAL_RNG, 2:4, Val(1)) isa SamplerRangeFast
     @test Sampler(GLOBAL_RNG, 2:4, Val(Inf)) isa SamplerRangeFast
 end
+
+@testset "RNGs broadcast as scalars: T" for T in (MersenneTwister, RandomDevice)
+    @test length.(rand.(T(), 1:3)) == 1:3
+end