Adds Webstacklib utilities and @interface macro

Http/src/Http.jl

@@ -4,7 +4,7 @@
 #
 module Http
 
-using Httplib
+using Webstacklib, Httplib
 include("RequestParser.jl")
 export HttpHandler,
        Server,
@@ -92,18 +92,16 @@ end
 # sockets` is populated. Concrete types of `WebsocketInterface` are required 
 # to define these methods.
 #
-abstract WebsocketInterface
-# `is_websocket_handshake` should determine if `req` is a valid websocket 
-# upgrade request.
-#
-function is_websocket_handshake(handler::WebsocketInterface, req::Request)
-    throw("`$(typeof(handler))` does not implement `is_websocket_handshake`.")
-end
-# `handle` is called when `is_websocket_handshake` returns true, and takes
-# full control of the connection.
-#
-function handle(handler::WebsocketInterface, req::Request, client::Client)
-    throw("`$(typeof(handler))` does not implement `handle`.")
+@interface type WebsocketInterface
+    # `is_websocket_handshake` should determine if `req` is a valid websocket 
+    # upgrade request.
+    #
+    is_websocket_handshake(handler::WebsocketInterface, req::Request)
+
+    # `handle` is called when `is_websocket_handshake` returns true, and takes
+    # full control of the connection.
+    #
+    handle(handler::WebsocketInterface, req::Request, client::Client)
 end
 
 # `Server` types encapsulate an `HttpHandler` and optional 

Webstacklib/src/Webstacklib.jl

@@ -0,0 +1,20 @@
+module Webstacklib
+    export @interface
+
+    macro interface(iexp::Expr)
+        iexp.head == :type || throw("@interface macro expects a type expression, got $(exp.head)")
+        name = iexp.args[2]
+        oexp = :(begin abstract $(esc(name)) end)
+        for exp in iexp.args[3].args
+            if exp.head == :call
+                strexp = string(exp)[3:end-1]
+                err = string("method ", strexp, " for interface ", name, " not implemented.")
+                fun = Expr(:function, esc(exp), quote
+                    throw($err)
+                end)
+                push!( oexp.args, fun )
+            end
+        end
+        oexp
+    end
+end