#154: subclassed ExceptionHandlers can't handle exceptions
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Reporter: cotto | Owner: whiteknight
Type: bug | Status: assigned
Priority: major | Milestone:
Component: core | Version: trunk
Severity: medium | Keywords: exception, subclass, exceptionhandler
Lang: | Patch:
Platform: all |
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Comment(by whiteknight):
Okay, I think I have this issue figured out. Our subclassed type inherits
from ExceptionHandler, which in turn inherits from Continuation PMC.
Continuation has a Parrot_Context ATTR which cannot be inherited by a PIR
subclass. Only INTVAL, FLOATVAL, PMC* and STRING* I think can be
inherited. When we try to use the subclassed handler, we call
{{{if (PMC_cont(handler)->current_results)}}}
The normal GET_ATTR_* macros would throw an exception here that we tried
to access an ATTR from a subclass that could not get accessed from a PIR
subclass. However, the {{{PMC_cont}}} macro does not throw such an
exception (that would have helped us identify the problem much earlier).
When we go to pass the results, somebody is using the {{{PMC_cont}} macro
and causing the problems that we see.
The good news: This should be fixable but we will have to add in a hackish
special case in Parrot_ex_throw_from_op to deal with PIR subclasses. I'll
try to work on that tonight.
The better news: This problem should disappear entirely once we've turned
Contexts into PMCs. See r596 for detail about that project.
There are several tickets like this: Where a PIR subclass of a built-in
PMC type cannot properly inherit methods, and I think we should check the
inheritance tree for non-inheritable ATTRs that might be the problem.
--
Ticket URL: <https://trac.parrot.org/parrot/ticket/154#comment:11>
Parrot <https://trac.parrot.org/parrot/>
Parrot Development
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