adds do syntax support

README.md

@@ -53,13 +53,26 @@ PortAudio.jl also provides convenience wrappers around the `PortAudioStream` typ
 
 ```julia
 stream = PortAudioStream(2, 2)
-write(stream, stream)
+try
+    # cancel with Ctrl-C
+    write(stream, stream)
+finally
+    close(stream)
+end
+```
+
+### Use `do` syntax to auto-close the stream
+```julia
+PortAudioStream(2, 2) do stream
+    write(stream, stream)
+end
 ```
 
 ### Open your built-in microphone and speaker by name
 ```julia
-stream = PortAudioStream("Built-in Microph", "Built-in Output")
+PortAudioStream("Built-in Microph", "Built-in Output") do stream
-write(stream, stream)
+    write(stream, stream)
+end
 ```
 
 ### Record 10 seconds of audio and save to an ogg file
@@ -79,6 +92,8 @@ julia> buf = read(stream, 10s)
 ▁▄▂▃▅▃▂▄▃▂▂▁▁▂▂▁▁▄▃▁▁▄▂▁▁▁▄▃▁▁▃▃▁▁▁▁▁▁▁▁▄▄▄▄▄▂▂▂▁▃▃▁▃▄▂▁▁▁▁▃▃▂▁▁▁▁▁▁▃▃▂▂▁▃▃▃▁▁▁▁
 ▁▄▂▃▅▃▂▄▃▂▂▁▁▂▂▁▁▄▃▁▁▄▂▁▁▁▄▃▁▁▃▃▁▁▁▁▁▁▁▁▄▄▄▄▄▂▂▂▁▃▃▁▃▄▂▁▁▁▁▃▃▂▁▁▁▁▁▁▃▃▂▂▁▃▃▃▁▁▁▁
 
+julia> close(stream)
+
 julia> save(joinpath(homedir(), "Desktop", "myvoice.ogg"), buf)
 ```
 

src/PortAudio.jl

@@ -210,6 +210,16 @@ function PortAudioStream(inchans=2, outchans=2; kwargs...)
     PortAudioStream(indevice, outdevice, inchans, outchans; kwargs...)
 end
 
+# handle do-syntax
+function PortAudioStream(fn::Function, args...; kwargs...)
+    str = PortAudioStream(args...; kwargs...)
+    try
+        fn(str)
+    finally
+        close(str)
+    end
+end
+
 const pa_inited = Ref(false)
 const active_streams = Set{PortAudioStream}()