From f4d970f85f2da7af85cd5b329f8de9a462d60f4b Mon Sep 17 00:00:00 2001
From: Jon Malmaud <malmaud@gmail.com>
Date: Wed, 17 Aug 2016 12:35:04 -0400
Subject: [PATCH] Add 'isassigned' for RefValue

---
 base/refpointer.jl | 1 +
 test/misc.jl       | 8 ++++++++
 2 files changed, 9 insertions(+)

diff --git a/base/refpointer.jl b/base/refpointer.jl
index 4cfd0e2080830..45f75752091a5 100644
--- a/base/refpointer.jl
+++ b/base/refpointer.jl
@@ -41,6 +41,7 @@ type RefValue{T} <: Ref{T}
     RefValue(x) = new(x)
 end
 RefValue{T}(x::T) = RefValue{T}(x)
+isassigned(x::RefValue) = isdefined(x, :x)
 
 Ref(x::Ref) = x
 Ref(x::Any) = RefValue(x)
diff --git a/test/misc.jl b/test/misc.jl
index 3592ee2de1ac3..54d51af7bd8d7 100644
--- a/test/misc.jl
+++ b/test/misc.jl
@@ -611,3 +611,11 @@ end
     @test Foo_19281().f[1] == ()
     @test Foo_19281().f[2] == (1, )
 end
+
+let
+    x_notdefined = Ref{String}()
+    @test !isassigned(x_notdefined)
+
+    x_defined = Ref{String}("Test")
+    @test isassigned(x_defined)
+end