core/stream: add Writable::write_to_bytes

Signed-off-by: Jean Privat <jean@pryen.org>

diff --git a/lib/core/stream.nit b/lib/core/stream.nit
index 3fc3f30..6d0278a 100644 (file)
--- a/lib/core/stream.nit
+++ b/lib/core/stream.nit
@@ -574,17 +574,32 @@ interface Writable
        # The specific logic it let to the concrete subclasses
        fun write_to(stream: Writer) is abstract
 
-       # Like `write_to` but return a new String (may be quite large)
+       # Like `write_to` but return a new String (may be quite large).
        #
-       # This funtionality is anectodical, since the point
-       # of streamable object to to be efficienlty written to a
-       # stream without having to allocate and concatenate strings
+       # This functionality is anecdotal, since the point
+       # of a streamable object is to be efficiently written to a
+       # stream without having to allocate and concatenate strings.
        fun write_to_string: String
        do
                var stream = new StringWriter
                write_to(stream)
                return stream.to_s
        end
+
+       # Like `write_to` but return a new Bytes (may be quite large)
+       #
+       # This functionality is anecdotal, since the point
+       # of a streamable object is to be efficiently written to a
+       # stream without having to allocate and concatenate buffers.
+       #
+       # Nevertheless, you might need this method if you want to know
+       # the byte size of a writable object.
+       fun write_to_bytes: Bytes
+       do
+               var stream = new BytesWriter
+               write_to(stream)
+               return stream.bytes
+       end
 end
 
 redef class Bytes