java:jinterface-implementation: multiple interfaces?

Alessio Stalla alessiostalla at
Thu Jul 30 07:57:26 UTC 2020

You may have luck by providing a list. However, I see a deeper problem.
Serializable is a marker interface: it has no methods, it only declares the
type serializable. However, you cannot just declare that an object is
serializable to make it so; all its components must be serializable as
well. This includes the invocation handler that ABCL creates under the
cover, as well as all the Lisp objects that you use for the implementation,
particularly functions and closures. And, bad news – those aren't
serializable. So, if Serializable is a requirement because those instances
will effectively be serialized – e.g., to persist them to a file or to send
them over the network – you're out of luck.

Ages ago I had started a branch to make most Lisp objects serializable, but
I don't remember how far I got. I don't think it was ever mature enough to
be merged, but many years have passed.

On Thu, 30 Jul 2020 at 05:22, Steven Nunez <steve_nunez at> wrote:

> Apologies, when I said "but I can't see adding multiple implementations",
> I meant multiple interfaces.
> On Thursday, July 30, 2020, 11:19:07 AM GMT+8, Steven Nunez <
> steve_nunez at> wrote:
> Is there a way to implement multiple interfaces on a single Java proxy?
> This code almost works:
> (java:jinterface-implementation
>  ""
>  "call" (lambda (s) (length s)))
> except that the proxy also needs to implement Serializable. The jproxy
> code
> <>
> in java.lisp seems to suggest that multiple implementations are allowed:
> (defgeneric jmake-proxy (interface implementation &optional lisp-this)
>   (:documentation "Returns a proxy Java object implementing the provided
> interface(s)...
> but I can't see adding multiple implementations in the code. I see there's
> a few jmake-proxy methods in there though: are there any documentation or
> examples for their usage? Lsw2 doesn't use this at all and I can't find any
> other good examples of using ABCL.
> Multiple interfaces from the jinterface-implementation function would be
> ideal, as the above code could then be wrapped with a macro to produce a
> 'spark-lambda' and be used nearly like the regular ABCL lambda.
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