[armedbear-devel] Some thoughts on classloaders, ...

Alessio Stalla alessiostalla at gmail.com
Tue Sep 22 08:42:02 UTC 2009

On Tue, Sep 22, 2009 at 10:28 AM, Don Cohen
<don-sourceforge-xxz at isis.cs3-inc.com> wrote:
> Alessio Stalla writes:
>  > The point is that classloaders already work like this! When
>  > classloader X loads a class, and that class refers to class C, X is
>  > asked by the JVM to load C as well. In abcl we are not using this
>  > feature, rather we use an ad-hoc loading model that needs temporary
>  > files. I propose to replace that completely and adopt the JVM way.
> Ok, I think I finally understand all you said initially.
> I'm sorry to have put you to so much trouble explaining it.
> I hope a few others will benefit from this explanation.

No problem at all, I myself find this explanation much better than the
first one :D

>  > ... However note that your example will probably be
>  > compiled by abcl into a call like G.getSymbolFunction().execute(x)
> Ok, that's a reasonable escape hatch.

I believe it works like this, but I haven't the sources at hand to check it.

>  > i.e. G will not be resolved to a class at compile time (else how would
>  > you handle redefinition?). However, what I'm talking about is (compile
>  > 'f (lambda (x) (flet ((g (k) k)) (g x)))) - here g is known at compile
>  > time, and compiled to its own class.
> (I understood that.  The question above was a new one that arose in my
> mind from what you had been describing.)
>  > What I propose is this: suppose f is compiled to a class named foo41
>  > and g to foo42, then in one of foo41's methods you'll have code like
>  > LispObject g = new foo42(). When loading foo41 we'll use our
>  > abcl-specific classloader which knows how to resolve foo42 too
>  > (because it knows where to read it from memory or from the file
>  > system, depending on the type of compilation), and everything
>  > magically works (I hope :)
> Sounds plausible but I can see why you say you hope.  Good luck.

I say hope because I don't believe in magic :D

> And thanks for your patience.

I have great patience, however I needn't use it to answer your posts;
making things clear for others makes them clearer to me, so it's not a
waste (provided the questions are intelligent, and yours were).


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