Improve efficiency/flexibility.

lib/trenni/uri.rb

@@ -30,18 +30,22 @@ def initialize(base, fragment, query)
 		attr :fragment
 		attr :query
 
-		def to_str
-			buffer = [escape_path(@base)]
+		def append(buffer)
+			buffer << escape_path(@base)
 
 			if @query&.any?
-				buffer.push(query_separator, query_part)
+				buffer << query_separator << query_part
 			end
 
-			# It's not clear if this is correct. According to the spec, it should be percent encoded.
-			# CGI.escape(' ') -> '+' which is not correct according to the RFC.
-			buffer.push('#', escape(@fragment)) if @fragment
+			if @fragment
+				buffer << '#' << escape(@fragment)
+			end
 
-			return buffer.join
+			return buffer
+		end
+
+		def to_str
+			append(String.new)
 		end
 
 		alias to_s to_str

spec/trenni/uri_spec.rb

@@ -46,4 +46,10 @@
 			expect(subject.to_s).to be == "I/%E2%9D%A4%EF%B8%8F/UNICODE?face=%F0%9F%98%80"
 		end
 	end
+
+	it "can be an attribute" do
+		tag = Trenni::Tag.closed('img', src: Trenni::URI('image.jpg', x: 10))
+
+		expect(tag.to_s).to be == '<img src="image.jpg?x=10"/>'
+	end
 end