in reply to Re: Problems with 'use lib'
in thread Problems with 'use lib'

I don't think this code will do what you want: 

BEGIN {
  my $projectLocation = '/some/other/place';
  use lib $projectLocation;
}

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The "use lib" inside the BEGIN block will be executed before the assignment since it is also inside the BEGIN block. Try this instead: 
my $projectLocation;
BEGIN {
  $projectLocation = '/some/other/place';
}
use lib $projectLocation;

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The "use" is like another BEGIN so these two pieces of code will be executed in sequence now.

-- Eric Hammond

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Re: Re: Re: Problems with 'use lib'
by shenme (Priest) on Aug 21, 2003 at 18:02 UTC
    I was going to say that wasn't true, but went back and looked at the last test program I was using and decided I hadn't tested that situation correctly.   Using code 
    BEGIN {
    my  $foo = 'foom';
    use lib $foo;
}

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    results in error messages 
    Use of uninitialized value in string eq at /usr/lib/perl5/5.8.0/i386-linux-thread-multi/lib.pm line 29.
Empty compile time value given to use lib at hotshot.pl line 5
    Using your code 
        my  $foo;
BEGIN {  $foo = 'foom'; }
    use lib $foo;
    printf "executing:  '%s'\n", join("', '", @INC );

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    returns the desired results 
    executing:  'foom', '/usr/lib/perl5/5.8.0/i386-linux-thread-multi', ... , '.'
    Just to try something different I tried 
    BEGIN {  our $foo = 'foom';  }
    use lib $foo;

    [download]
    which also worked.

    Another thing to put in the list of things to re-study.   Key is that "use" (and other pragmas?) are executed (at compile time) before surrounding code at the same apparent 'level'.   By enclosing code in a BEGIN block ahead of the "use" we force it into compile time execution before the following "use" is executed.   (Or something like that ;-)

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