Prettify summary using showarg

Author: timholy

src/OffsetArrays.jl

@@ -219,4 +219,18 @@ end
 @inline unsafe_getindex(a::OffsetSubArray, I::Union{Integer,CartesianIndex}...) = unsafe_getindex(a, Base.IteratorsMD.flatten(I)...)
 @inline unsafe_setindex!(a::OffsetSubArray, val, I::Union{Integer,CartesianIndex}...) = unsafe_setindex!(a, val, Base.IteratorsMD.flatten(I)...)
 
+if VERSION >= v"0.7.0-DEV.1790"
+    function Base.showarg(io::IO, a::OffsetArray, toplevel)
+        print(io, "OffsetArray(")
+        Base.showarg(io, parent(a), false)
+        print(io, ", ")
+        printindices(io, indices(a)...)
+        print(io, ')')
+        toplevel && print(io, " with eltype ", eltype(a))
+    end
+    printindices(io::IO, ind1, inds...) =
+        (print(io, ind1, ", "); printindices(io, inds...))
+    printindices(io::IO, ind1) = print(io, ind1)
+end
+
 end # module

test/runtests.jl

@@ -353,3 +353,9 @@ for i = -3:3
     @test a[i] == i
 end
 @test unsafe_sum(a) == 0
+
+if VERSION >= v"0.7.0-DEV.1790"
+    a = OffsetArray([1 2; 3 4], -1:0, 5:6)
+    @test summary(a) == "OffsetArray(::Array{$(Int),2}, -1:0, 5:6) with eltype $(Int) with indices -1:0×5:6"
+    @test summary(view(a, :, 5)) == "view(OffsetArray(::Array{Int64,2}, -1:0, 5:6), :, 5) with eltype Int64 with indices -1:0"
+end