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Re: Win32 @INC behavior

by blm (Hermit)
on Nov 16, 2005 at 04:02 UTC ( #508891=note: print w/replies, xml ) Need Help??

in reply to Win32 @INC behavior

What do you copy to the new computer? Just perl.exe or the whole bin directory? Do you update the PATH system variable?

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Re^2: Win32 @INC behavior
by richz (Beadle) on Nov 16, 2005 at 04:08 UTC
    This is all on the same computer. I am not relying on my PATH to run perl and I am just copying perl.exe and the perl56.dll. I ran dependency walker and that is the only dynamically linked non-OS library linked in perl.exe.

    I was always under the impression that the @INC variable is fixed once you compile perl.exe but there was on thread here that mentioned it seems to be somewhat dynamic but not in the way I'm finding out. That thread seemed to indicate that moving perl.exe around would result in @INC being adjusted so the directories it contains have their path adjusted accordingly.

      In my attempts to mimick this problem I got an error about missing when running perl -V when I removed all the perl except perl.exe and perl58.dll and perl5.8.0.exe (Yes I am doing this under perl 5.8 because that is all I have on Win32). The that it is refering to (I think) is c:\perl\lib\ and it contains alot of the info needed for the -V screen. I don't know if this helps you.

      @INC is the result of all perllib additions that have been made by perl upon startup. It is not fixed at all. Although there is a portion of it that is fixed at compile time. The @INC is a combination of compile time settings, PERLLIB environment variable, perl command line -I parameters and use lib statements.

      For example on linux, if you do:

      PERLLIB=envbar perl -I cmdfoo -V -e "use lib ('usebaz');"

      You will see the resulting @INC :

      @INC: usebaz cmdfoo envbar /usr/lib/perl5/5.6.1/i386-linux /usr/lib/perl5/5.6.1 /usr/lib/perl5/site_perl/5.6.1/i386-linux /usr/lib/perl5/site_perl/5.6.1 /usr/lib/perl5/site_perl/5.6.0/i386-linux /usr/lib/perl5/site_perl/5.6.0 /usr/lib/perl5/site_perl /usr/lib/perl5/vendor_perl/5.6.1/i386-linux /usr/lib/perl5/vendor_perl/5.6.1 /usr/lib/perl5/vendor_perl .

      There appears to be an order of precidence here too. use lib is first, -I option is second, PERLLIB is third and compiled settings is fourth.

      Update: added use lib to the example.

      Hazah! I'm Employed! But this place sucks

        Yeah I guess I meant fixed if not modified using environment variable, command line option, etc. The location of the perl executable seems to affect the @INC variable and I think a reply further down in this thread is a convincing reason. Thanks.
      Note: I'm doing a lot of handwaving here... I seem to recall having read about this, but I've not looked it up to confirm my beliefs. I'll look it up later, I promise.
      I was always under the impression that the @INC variable is fixed once you compile perl.exe
      That's right. That's even the case for Perl on Windows... Except: perl itself changes the directories found in the hardwired @INC inside the perl exectutable, into directories relative to where it currently resides. That happens to lib (relative position to perl: ../lib) and site/lib (relative position: ../site/lib), where the perl executable resides in bin, relative to the perl installation root.

      You could say it's a simple s/^$HARDWIRED_ROOT/$CURRENT_ROOT/, done inside perl.

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