Change Window() async option to pure julia kwarg.

Change `:async => false` opt to `async=false` keyword argument.

src/AtomShell/window.jl

@@ -24,17 +24,16 @@ const window_defaults = @d(:url => "about:blank",
 
 raw_window(a::Electron, opts) = @js a createWindow($(merge(window_defaults, opts)))
 
-function Window(a::Shell, opts::AbstractDict = Dict())
+function Window(a::Shell, opts::AbstractDict = Dict(); async=true)
+  # TODO: Custom urls don't support async b/c don't load Blink.js. (Same as https://github.com/JunoLab/Blink.jl/issues/150)
   return haskey(opts, :url) ?
     Window(raw_window(a, opts), a, nothing) :
-    Window(a, Page(), opts)
+    Window(a, Page(), opts, async=async)
 end
 
-function Window(a::Shell, content::Page, opts::AbstractDict = Dict())
+function Window(a::Shell, content::Page, opts::AbstractDict = Dict(); async=true)
   url = Blink.localurl(content)
-  is_async(opts) = get(opts, :async, true)  # Async default: true
-  callback = !is_async(opts)
-  if callback
+  if !async
       # Send the callback id as a query param in the url.
       id, cond = Blink.callback!()
       url *= "?callback=$id"
@@ -43,7 +42,7 @@ function Window(a::Shell, content::Page, opts::AbstractDict = Dict())
   opts = merge(opts, Dict(:url => url))
   w = Window(raw_window(a, opts), a, content)
   # If callback is requested, wait until the window has finished loading.
-  if callback
+  if !async
       val = wait(cond)
       if isa(val, AbstractDict) && get(val, "type", "") == "error"
           err = JSError(get(val, "name", "unknown"), get(val, "message", "blank"))
@@ -53,7 +52,7 @@ function Window(a::Shell, content::Page, opts::AbstractDict = Dict())
   return w
 end
 
-Window(args...) = Window(shell(), args...)
+Window(args...; kwargs...) = Window(shell(), args...; kwargs...)
 
 dot(a::Electron, win::Integer, code; callback = true) =
   js(a, :(withwin($(win), $(jsstring(code)...))),

test/AtomShell/window.jl

@@ -2,7 +2,7 @@ using Blink
 using Test
 
 @testset "size Tests" begin
-    w = Window(Blink.@d(:show => false, :width=>150, :height=>100, :async=>false));
+    w = Window(Blink.@d(:show => false, :width=>150, :height=>100), async=false);
     @test size(w) == [150,100]
 
     size(w, 200,200)

test/content/api.jl

@@ -2,7 +2,7 @@ using Blink
 using Test
 
 @testset "content! Tests" begin
-    w = Window(Blink.@d(:show => false, :async=>false));
+    w = Window(Blink.@d(:show => false), async=false);
     body!(w, "", async=false);
     @test (@js w document.querySelector("body").innerHTML) == ""
 
@@ -20,22 +20,22 @@ using Test
     fadeTestHtml = """<script>var testJS = "test";</script><div id="d">hi world</div>"""
     @testset "Fade True" begin
         # Must create a new window to ensure javascript is reset.
-        w = Window(Blink.@d(:show => false));
+        w = Window(Blink.@d(:show => false), async=false);
 
         body!(w, fadeTestHtml; fade=true, async=false);
         @test (@js w testJS) == "test"
     end
     @testset "Fade False" begin
         # Must create a new window to ensure javascript is reset.
-        w = Window(Blink.@d(:show => false, :async=>false));
+        w = Window(Blink.@d(:show => false), async=false);
 
         body!(w, fadeTestHtml; fade=false, async=false);
         @test (@js w testJS) == "test"
     end
 end
 
 @testset "Sync/Async content reload tests" begin
-    w = Window(Blink.@d(:show => false, :async=>false));
+    w = Window(Blink.@d(:show => false), async=false);
     sleep_content(seconds) = """
         <script>
             function spinsleep(ms) {