Merge pull request #11576 from JuliaLang/sb/nullable

add 2 argument Nullable constructor

Author: StefanKarpinski

base/base.jl

@@ -105,5 +105,5 @@ immutable Nullable{T}
     value::T
 
     Nullable() = new(true)
-    Nullable(value::T) = new(false, value)
+    Nullable(value::T, isnull::Bool=false) = new(isnull, value)
 end

base/nullable.jl

@@ -3,7 +3,7 @@
 immutable NullException <: Exception
 end
 
-Nullable{T}(value::T) = Nullable{T}(value)
+Nullable{T}(value::T, isnull::Bool=false) = Nullable{T}(value, isnull)
 Nullable() = Nullable{Union()}()
 
 eltype{T}(::Type{Nullable{T}}) = T

test/nullable.jl

@@ -40,6 +40,23 @@ for T in types
     @test eltype(x) === T
 end
 
+# Nullable{T}(value::T, isnull::Bool) = new(isnull, value)
+for T in types
+    x = Nullable{T}(zero(T),false)
+    @test x.isnull === false
+    @test isa(x.value, T)
+    @test x.value === zero(T)
+    @test eltype(x) === T
+
+    x = Nullable{T}(zero(T),true)
+    @test x.isnull === true
+    @test isa(x.value, T)
+    @test eltype(Nullable{T}) === T
+    @test eltype(x) === T
+end
+
+
+
 # immutable NullException <: Exception
 @test isa(NullException(), NullException)
 @test_throws NullException throw(NullException())