Re: Private names

> Hi Janne.
>
> I was under the impression that the
> ad-hoc-initialization-block-using-anonymous-subclass trick was the
> "standard way" to do this kind of thing in Scala. In your example, I
> infer that Message is a Java class, but if it was written in Scala,
> one idiom for initialization would be to declare abstract vals, like
> this:
>
> abstract class Message {
>   val displayName:String
>   val content:String
> }
>
> sw sendMessage (new Message {
>    val displayName = somename
>    val content = format("Hello, %s! %s!", displayName, somecontent)
> })

>
> On Oct 30, 2007 8:29 AM, Janne Savukoski <janne@...> wrote:
> > Hello,
> >
> > This feels a little stupid, and I'm sure there's something
> > fundamentally n00b in this, but anyways... I've been experimenting
> > with this kind of structure (note the pipe, '|', on 2nd line):
> >
> > <clip>
> > 1: sw.sendMessage {
> > 2:   new Message | { m =>
> > 3:     m.setDisplayName(somename)
> > 4:     m.setContent(format("Hello, %s! %s!", displayName, somecontent))
> > 5:   }
> > 6: }
> > </clip>
> >
> > which is similar to
> >
> > 1: val m = new Message
> > 2: m.setDisplayName(somename)
> > 3: m.setContent(format("Hello, %s! %s!", displayName, somecontent))
> > 4: sw.sendMessage(m)
> >
> > and
> >
> > 1: sw.sendMessage {
> > 2:   val m = new Message
> > 3:   m.setDisplayName(somename)
> > 4:   m.setContent(format("Hello, %s! %s!", displayName, somecontent))
> > 5:   m
> > 6: }
> >
> >
> > The last one was my favorite before the pipe, but it suffers from the
> > explicit return. The second I don't like a bit as it exposes the name
> > 'm' that is relevant only in the context of the 'sendMessage'
> > invocation.
> >
> > In the first case the pipe—which returns the object itself—replaces an
> > ad-hoc-initialization-block-using-anonymous-subclass. More generally,
> > with pipe I can write a block with a 'private' reference to the
> > context object. (or something...)
> >
> > The pipe is defined simply as
> >
> > implicit def pipe4Any[a](any: a) = new AnyRef { def |(f:a => Unit): a
> > = { f(any); any } }
> >
> > Another nice use case was with logging:
> >
> > 1: rs.report(WARNING, root, format("Resource not found: %s",
> > f.getAbsolutePath) | (warn(_)))
> >
> > where the message "Resource n..." is logged ('warn', shortcut to
> > commons logging) while passed on to the report method. (No
> > ad-hoc-initialization-block-using-anonymous-subclass here.)
> >
> > So, this is just such a trivial use case that I'm sure there's some
> > standard way to do this. Please, feel free to show me the light. :)
> >
> >
> > -janne
> >
>
>
>
> --
> Rafael de F. Ferreira.
> http://www.rafaelferreira.net/
>