OT: Apache::Registry - global vars cleared?

[___cliff rayman___ <cl...@genwax.com>]

Stas Bekman wrote:

> On Thu, 3 Aug 2000, ___cliff rayman___ wrote:
>
> > "Keith G. Murphy" wrote:
> >
> > > ___cliff rayman___ wrote:
> > > >
> > > > The perl interpreter has a one global symbol table called the
stash where
> > > > all global variables are referenced by package and by variable
name.
> > > > Since the interpreter does not go away when a script is
recompiled, neither
> > > > does the stash or any of the items contained within it.  Some
programmers
> > > > are probably using this as a feature, and therefore it is
unlikely that it
> > > > will change.
> > > > This is really standard perl stuff and it has nothing to do with

> > > > Apache::Registry in particular.  It is just something the
average perl
> > > > programmer does not come across since we usually load the
interpreter, load
> > > > a program, run the program, exit the interpreter.
> > > >
> > > > check out:
> > > >
http://thingy.kcilink.com/modperlguide/porting/Global_Variables_Persistence.html

> > > >
> > > Thanks for the info and the link.
> > >
> > > One note though.  The info in the link really doesn`t pertain to
my
> > > specific question:
> > >
> > > "global variables persist inside the same process from request to
> > > request"
> > >
> > > I knew that; I was surprised that they did even on a recompilation
of
> > > the script, which the link info doesn`t really refer to.
> >
> > i will see if i can find a good place in the guide to add it and
i`ll send stas the
> > patch.
>
> I`m not sure there is a need for a patch. I think you confuse,
> something. When the script is recompiled all the variables belonging
to
> the package decalared by Apache::Registry or similar are getting
reset. If
> you require/use() some modules that declare packages and have global
> variables -- these won`t be reset unless reloaded or initialized in
your
> code.

are u sure about this?  not looking to argue with u, just trying to fine
tune my knowledge of perl and mod_perl in particular.

the following code works similarly to how Apache::Registry loads a sub:
perl -e '
$sub=q{package thepkg; use vars qw($thevar); print "evaled sub with
\$thevar=$thevar\n";};
package main;
$thepkg::thevar="first outside value";
eval $sub || die $@;
package main;
print "\$thepkg::thevar=$thepkg::thevar\n";
$thepkg::thevar="second outside value";
eval $sub || die $@;
print "\$thepkg::thevar=$thepkg::thevar\n";
'

the above code returns:
evaled sub with $thevar=first outside value
$thepkg::thevar=first outside value
evaled sub with $thevar=second outside value
$thepkg::thevar=second outside value


eval $sub does not reinitialize any package vars that i can see
(although it is late).  perhaps Apache::Registry is clearing the global
vars? i looked at Apache::Registry.pm and did not see anyplace it was
doing that.  there are calls to some C code which did not look like they
were reinitializing the package vars but the perl internals are beyond
my comprehension. :-(

stas, if u don't have the tuits to answer - no problem - i know you're
busy.  perhaps someone else knows the answer.

--
___cliff rayman___cliff@genwax.com___http://www.genwax.com/

Re: OT: Apache::Registry - global vars cleared?

[___cliff rayman___ <cl...@genwax.com>]

earlier Stas Bekman said:

> > > I`m not sure there is a need for a patch. I think you confuse,
> > > something. When the script is recompiled all the variables belonging
> > > to the package decalared by Apache::Registry or similar are getting
> > > reset. If you require/use() some modules that declare packages and have global
> > > variables -- these won`t be reset unless reloaded or initialized in your code.
> >
> --snip--
>

then later:

> Now once this package is built and compiled, *nothing* happens to it --
> it's like a loaded from the file module. If you don't initialize vars at
> the beginning of your script. And no, Apache::Registry doesn't reset the
> global vars.

ah.  that's what I thought.  but previously you said "all the variables belonging to
the packaged decalared by Apache::Registry or similar are getting reset."  that is the
point i was arguing, but it looks like we both agree. perhaps you meant to say "all
the lexicals belonging to the file loaded by Apache::Registry or similar are getting
reset".

back to the original posting that started this thread, the poster was unaware that the
package variables would not be reset when the file containing that package was
recompiled.  we both agree that they will not be reset.  he did not think that this
fact was clear in the guide.
--
___cliff rayman___cliff@genwax.com___http://www.genwax.com/

Re: OT: Apache::Registry - global vars cleared?

[Stas Bekman <st...@stason.org>]

On Mon, 7 Aug 2000, ___cliff rayman___ wrote:

> Stas Bekman wrote:
> 
> > On Thu, 3 Aug 2000, ___cliff rayman___ wrote:
> >
> > > "Keith G. Murphy" wrote:
> > >
> > > > ___cliff rayman___ wrote:
> > > > >
> > > > > The perl interpreter has a one global symbol table called the
> stash where
> > > > > all global variables are referenced by package and by variable
> name.
> > > > > Since the interpreter does not go away when a script is
> recompiled, neither
> > > > > does the stash or any of the items contained within it.  Some
> programmers
> > > > > are probably using this as a feature, and therefore it is
> unlikely that it
> > > > > will change.
> > > > > This is really standard perl stuff and it has nothing to do with
> 
> > > > > Apache::Registry in particular.  It is just something the
> average perl
> > > > > programmer does not come across since we usually load the
> interpreter, load
> > > > > a program, run the program, exit the interpreter.
> > > > >
> > > > > check out:
> > > > >
> http://thingy.kcilink.com/modperlguide/porting/Global_Variables_Persistence.html
> 
> > > > >
> > > > Thanks for the info and the link.
> > > >
> > > > One note though.  The info in the link really doesn`t pertain to
> my
> > > > specific question:
> > > >
> > > > "global variables persist inside the same process from request to
> > > > request"
> > > >
> > > > I knew that; I was surprised that they did even on a recompilation
> of
> > > > the script, which the link info doesn`t really refer to.
> > >
> > > i will see if i can find a good place in the guide to add it and
> i`ll send stas the
> > > patch.
> >
> > I`m not sure there is a need for a patch. I think you confuse,
> > something. When the script is recompiled all the variables belonging
> to
> > the package decalared by Apache::Registry or similar are getting
> reset. If
> > you require/use() some modules that declare packages and have global
> > variables -- these won`t be reset unless reloaded or initialized in
> your
> > code.
> 
> are u sure about this?  not looking to argue with u, just trying to fine
> tune my knowledge of perl and mod_perl in particular.
> 
> the following code works similarly to how Apache::Registry loads a sub:
> perl -e '
> $sub=q{package thepkg; use vars qw($thevar); print "evaled sub with
> \$thevar=$thevar\n";};
> package main;
> $thepkg::thevar="first outside value";
> eval $sub || die $@;
> package main;
> print "\$thepkg::thevar=$thepkg::thevar\n";
> $thepkg::thevar="second outside value";
> eval $sub || die $@;
> print "\$thepkg::thevar=$thepkg::thevar\n";
> '
> 
> the above code returns:
> evaled sub with $thevar=first outside value
> $thepkg::thevar=first outside value
> evaled sub with $thevar=second outside value
> $thepkg::thevar=second outside value
> 
> 
> eval $sub does not reinitialize any package vars that i can see
> (although it is late).  perhaps Apache::Registry is clearing the global
> vars? i looked at Apache::Registry.pm and did not see anyplace it was
> doing that.  there are calls to some C code which did not look like they
> were reinitializing the package vars but the perl internals are beyond
> my comprehension. :-(
> 
> stas, if u don't have the tuits to answer - no problem - i know you're
> busy.  perhaps someone else knows the answer.

Cliff, I'm not sure what you are trying to show with the above code, what
you should do is to run the script under Apache::DB and see how
Apache::Registry generates the package. See:
http://perl.apache.org/guide/porting.html#The_First_Mystery

Now once this package is built and compiled, *nothing* happens to it --
it's like a loaded from the file module. If you don't initialize vars at
the beginning of your script. And no, Apache::Registry doesn't reset the
global vars. Apache::PerlRun does that.


_____________________________________________________________________
Stas Bekman              JAm_pH     --   Just Another mod_perl Hacker
http://stason.org/       mod_perl Guide  http://perl.apache.org/guide 
mailto:stas@stason.org   http://apachetoday.com http://jazzvalley.com
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