[armedbear-devel] Catching CL errors in java

[Alessio Stalla]

Sorry, to clarify: defparameter is a friend of setf when used like you
did, which is not how it's normally used (defparameter defines a
global dynamic variable and, as a side effect, modifies its value if
it already had one, but you never use it just for its side effect).
You can imagine defparameter as a shorthand for a defvar followed by a
setf.

On Tue, Feb 19, 2013 at 6:00 PM, Alessio Stalla <alessiostalla at gmail.com> wrote:
> I don't think the package is the culprit. Your package most probably
> USEs the CL package, or many other things would not work as you'd
> expect.
>
> Answering your earlier question, the correct way would be (setf
> *debugger-hook* ...) rather than defparameter, or even better binding
> instead of assigning - (let ((*debugger-hook* ...)) (do-your-stuff)).
>
> But I don't think that can make a difference between working and not
> working at all. It is more of a question of good style. Perhaps you're
> not considering thread-local bindings? If you run your
> defparameter/setf form on one thread, but .eval is called on another
> thread (and with a GUI involved, that is very probable), then chances
> are that the code in your .eval call is running in a dynamic
> environment where *debugger-hook* is locally rebound, and thus the
> global binding that you modify with defparameter/setf is shadowed. You
> can detect it by printing the value of *debugger-hook* in an .eval
> call triggered by the GUI. If that is the case, you should make sure
> to assign a new value to *debugger-hook* on the right thread, or,
> better, to use (let ...) as shown above. Let me stress that using LET
> is usually what you want in Lisp, especially when dealing with dynamic
> variables; a good rule of thumb is: avoid SETF and friends
> (defparameter is a friend) unless you're working on local variables.
> Of course, experts know when and how to break the rules :D but if
> you're a beginner, sticking to that style will make things easier to
> understand and debug, once you enter the right mindset.
>
> hth,
> Alessio
>
> On Tue, Feb 19, 2013 at 5:50 PM, Jonathan Fischer Friberg
> <odyssomay at gmail.com> wrote:
>> It might be that I'm in the wrong package. Although the repl is in cl-user,
>> and even if I change to that package the code in the previous mail has no
>> effect.
>>
>> Jonathan
>>
>>
>> On Tue, Feb 19, 2013 at 5:36 PM, Jonathan Fischer Friberg
>> <odyssomay at gmail.com> wrote:
>>>
>>> I don't know if this is the correct way to do it, but I did:
>>>
>>> (defparameter *debugger-hook*  #'sys::%debugger-hook-function)
>>>
>>> In the repl (from running java -jar abcl.jar), this worked as expected.
>>> However, I can't seem to get it working with the .eval function of my
>>> interpreter instance.
>>>
>>> Jonathan
>>>
>>>
>>> On Tue, Feb 19, 2013 at 5:07 PM, Alessio Stalla <alessiostalla at gmail.com>
>>> wrote:
>>>>
>>>> Short story: if you call into Lisp using the JSR-223 API, conditions
>>>> are automatically rethrown as Java exceptions.
>>>>
>>>> Long story: the way this is implemented is by binding *debugger-hook*
>>>> to an internal, probably undocumented function, that already does what
>>>> you want. It is called sys::%debugger-hook-function.
>>>>
>>>> On Tue, Feb 19, 2013 at 4:25 PM, Jonathan Fischer Friberg
>>>> <odyssomay at gmail.com> wrote:
>>>> > I should add that a solution from inside CL would also work. I'm using
>>>> > the
>>>> > ABCL eval to execute all code, so maybe I could wrap the call with
>>>> > something
>>>> > like this:
>>>> >
>>>> > (handler-case
>>>> >    (... do-stuff ...)
>>>> >    (... catch CL-condition + throw java exception ...))
>>>> >
>>>> > I don't know if that would work. Also, my CL skills are not good enough
>>>> > to
>>>> > finish the code above (how do I capture all conditions?), so help would
>>>> > be
>>>> > appreciated.
>>>> >
>>>> > Jonathan
>>>> >
>>>> >
>>>> > On Tue, Feb 19, 2013 at 3:30 PM, Jonathan Fischer Friberg
>>>> > <odyssomay at gmail.com> wrote:
>>>> >>
>>>> >> Hi again, :)
>>>> >>
>>>> >> I'm currently running CL-code from java. The gui is completely
>>>> >> implemented
>>>> >> on the java side. It would be nice if all errors occuring inside abcl
>>>> >> could
>>>> >> be captured from the java side (to be displayed in the gui as an
>>>> >> error). Is
>>>> >> that possible?
>>>> >>
>>>> >> Jonathan
>>>> >
>>>> >
>>>> >
>>>> > _______________________________________________
>>>> > armedbear-devel mailing list
>>>> > armedbear-devel at common-lisp.net
>>>> > http://lists.common-lisp.net/cgi-bin/mailman/listinfo/armedbear-devel
>>>> >
>>>>
>>>>
>>>>
>>>> --
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>>>>
>>>> http://ripple-project.org Ripple, social credit system
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>>>
>>>
>>
>
>
>
> --
> Some gratuitous spam:
>
> http://ripple-project.org Ripple, social credit system
> http://villages.cc Villages.cc, Ripple-powered community economy
> http://common-lisp.net/project/armedbear ABCL, Common Lisp on the JVM
> http://code.google.com/p/tapulli my current open source projects
> http://www.manydesigns.com/ ManyDesigns Portofino, open source
> model-driven Java web application framework



-- 
Some gratuitous spam:

http://ripple-project.org Ripple, social credit system
http://villages.cc Villages.cc, Ripple-powered community economy
http://common-lisp.net/project/armedbear ABCL, Common Lisp on the JVM
http://code.google.com/p/tapulli my current open source projects
http://www.manydesigns.com/ ManyDesigns Portofino, open source
model-driven Java web application framework