implement printfile (complementary to parsefile)

src/JSON.jl

@@ -21,7 +21,7 @@ using .Parser: parse, parsefile
 using .Writer: show_json, json, lower, print, StructuralContext, show_element,
                show_string, show_key, show_pair, show_null, begin_array,
                end_array, begin_object, end_object, indent, delimit, separate,
-               JSONText
+               JSONText, printfile
 using .Serializations: Serialization, CommonSerialization,
                        StandardSerialization
 

src/Writer.jl

@@ -351,6 +351,15 @@ print(io::IO, obj) = show_json(io, StandardSerialization(), obj)
 print(a, indent) = print(stdout, a, indent)
 print(a) = print(stdout, a)
 
+"""
+    printfile(filename::AbstractString, printargs...)
+
+A convenience wrapper that opens the `filename` for writing and prints the JSON
+to it. All arguments other than `filename` are forwarded to `print`.
+"""
+printfile(filename::AbstractString, printargs...) =
+    open(io -> print(io, printargs...), filename, "w")
+
 """
     json(a)
     json(a, indent::Int)

test/serializer.jl

@@ -85,6 +85,13 @@ let filename = tempname()
     rm(filename)
 end
 
+# test convenience printing to file
+let filename = tempname()
+    JSON.printfile(filename, Any[1, 2, 3.0])
+    @test read(filename, String) == "[1,2,3.0]"
+    rm(filename)
+end
+
 # issue #184: serializing a 0-dimensional array
 @test sprint(JSON.show_json, JSON.StandardSerialization(), view([184], 1)) == "184"