[GSoC] Parameter protocols in CL

[Charles Turner]

On 19 July 2012 23:56, Per Bothner <per@bothner.com> wrote:
> So what you need to do is add a method to LispPackage like:
>
>   public static LispPackage(String uri, SimpleSymbol prefix) { ... }
>
> or better, override  writeExternal:
>
>   public void writeExternal(ObjectOutput out) throws IOException
>   {
>     out.writeObject(getName());
>     out.writeObject(prefix);
>   }
>
> and then implement:
>
>   public static LispPackage(String name) { ... }
>
> where the ... should be the equivalent of find-package-or-error.

I assume you mean public static LispPackage {make,valueOf}. I've tried
both approaches, as well as a constructor approach. All with the
writeExternal() method as you sent. I still get the Literals error
though. I'm setting my *package* variable up like this now:

LispPackage:
public static ThreadLocation<LispPackage> currentPackage
    = new ThreadLocation<LispPackage>("package");
static { currentPackage.setGlobal(CLNamespace); }

CommonLisp:
defAliasStFld("*package*", "gnu.kawa.lispexpr.LispPackage",
                    "currentPackage");

I tried the LList approach of just empty constructor & writeExternal
method. This worked in that the Literals error went away, so I must be
misunderstanding something else. I tried

public LispPackage(String name) { // do nothing for now }
public void writeExternal(ObjectOutput out) throws IOException
  {
    out.writeObject(getName());
    out.writeObject(prefix);
  }

As I think you suggested, but that still have the error, as well as
what I thought was the correct method:

public LispPackage(String name, SimpleSymbol prefix) { // do nothing for now }
writeExternal as before.

I do have to declare an empty constructor in addition to the ones
above, because I use it in other places initializing a new package,
new LispPackage();

And in fact, I implemented a valueOf method in LispPackage some time
ago, which hasn't seemed to solve the problem either:

 public static LispPackage valueOf (String name)
  {
    if (name == null)
      name = "";
    synchronized (nsTable)
      {
	Namespace ns = (Namespace) nsTable.get(name);
	if (ns != null)
	  return (LispPackage) ns;
	ns = new LispPackage ();
	ns.setName(name.intern());
	Namespace.nsTable.put(name, ns);
	return (LispPackage) ns;
      }
  }

> Now there is still a mystery to me why you sometimes get this error
> and sometimes not.

Oh no, it's reproducible. I always get it after a recompilation of the
source file containing (setq *package* package). Not for the first
compilation, which if I've absored any of the discussion from the
internals page, is understandable.

Thanks,
Charles.