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Postings from October 2003
On Fri, Oct 31, 2003 at 01:24:53AM +0000, hv@crypt.org wrote:
> Stas Bekman <stas@stason.org> wrote:
> :Nicholas Clark wrote:
> :
> :>>Dave, please see my followup to p5p. The patch 21496 is the one that broke
> :>>mp1 test suite.
> :>
> :>
> :> I have reverted this change. I'll reconsider an improved version
> :> for 5.8.3.
> :
> :Thanks Nick.
> :
> :> Both remain in blead. (until/unless Hugo says otherwise)
> :
> :For the blead case, does the test that I've posted seem to be a valid one that
> :shows that this patch breaks things?
> :http://www.xray.mpe.mpg.de/mailing-lists/perl5-porters/2003-10/msg01457.html
> :Hugo?
>
> I think it is valid, but not sufficient.
I'm not sure it's even valid. This line:
chdir $expected_failure ? $not_cwd : $cwd;
doesn't do what you think it does. Try
chdir($expected_failure ? $not_cwd : $cwd) or die;
instead. Test results become identical pre- and post-patch with this
fix.
As to the original problem:
Imagine a real world situation: program A tries to load module Foo, but
fails for some reason. Now program B tries to load module Foo and it
succeeds (e.g. this time loaded from the proper directory, or some other
condition became true). Now run both program from a persistent enviroment
like mod_perl. Program A prevents from program B to load module Foo. The
only way to fix that problem is to delete $INC{"Foo.pm"} in program B.
This is not the only way. Since module Foo is relying on dynamic
loading conditions it has the option of returning 0 instead of croaking
when conditions aren't right but may become right later. This will
defeat the caching mechanism.
In any case, the above problem exists in older perls too since failures
were always cached; they were just cached as successes before. My
apologies if I'm missing the point somewhere. I haven't been following
this thread with the scintillating subject of "5.8.2 perldelta".
> That makes 7 tests, all of which I think perl should pass.
Assuming that the test wasn't buggy, I'm not convinced that the
exists $INC{$file}
tests should necessarily pass. We could just as easily cache failures
in a separate internal hash. I like Nick's suggestion of
PL_sv_placeholder. That also wouldn't show up under exists, right?
But to test for this in pp_require, do we have an hv_fetch equivalent
that will return PL_sv_placeholder or should we just add a flag? I'll
look at changing this in blead if no one objects.
--
Rick Delaney
rick@bort.ca