http://www.perlmonks.org?node_id=222277


in reply to modify @INC

BTW, if all you want to do is add another directory for including modules in your code, use the 'use lib' directive instead. Rather than adding a directory to @INC as you have done, do this:

use lib '/home/user/directory';

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Now of course, your example uses a variable to add to @INC rather than a string. 'use lib' will not take a variable since it's done during the compile stage. And why remove the last entry (the dot) from the list in the first place? You can just push @INC, $your_path right off the bat. Unless you for some reason require that perl search your directory before the current one for modules. Though I suppose the current directory should be checked as a last resort :) Maybe I'll quiet down... 
-------------------------------------
eval reverse@{[lreP
=>q{ tsuJ\{qq},' rehtonA'
,q{\}rekcaH },' tnirp']}[1+1+
1,1-1,1+1,1*1,(1+1)*(1+1)];
-------------------------------------

Replies are listed 'Best First'.
Re^2: modify @INC
by Aristotle (Chancellor) on Dec 26, 2002 at 17:17 UTC
    lib will take a variable. You just have to initialize that in a BEGIN block beforehand. This is Perl - compilation and execution are freely nestable.

    Makeshifts last the longest.

[reply]
      Would it be an option to do something like:

      $a="/my/module/path";
eval "use lib '$a'";
eval { use MyModule; }

      [download]
      I recall once using eval & use together to dynamically load specific modules when needed... This was before I knew about AUTOLOAD and SelfLoader and all...
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[d/l]
        No, that won't work. The use inside the eval BLOCK is compiled at compile time, but the string in eval EXPR is not. eval "use Foo"; is nothing but an obfuscated way to say require Foo; Foo->import;

        Neither case is a job for eval here. If you want variable paths at compile time, you do the following:

        my $libpath;
BEGIN { $libpath = "/foo/bar"; }
use lib $libpath;

        [download]
        If you want to load modules with dynamic @INC at runtime, you make use of the aforemention construct: 
        {
    local @INC = ("/foo/bar", @INC);
    require Foo;
    Foo->import;
}

        [download]
        eval will not help. And $a is a really awful name for a variable (plus $a and $b are reserved for sort). :)

        Makeshifts last the longest.

[reply]
[d/l]
[select]
      Mmm... I just ran a test script and got a working version, but I can't get it to not display warning messages.

      BEGIN {
  my $a = "c:/";
  use lib "$a";
}

use GetWords;
print new GetWords;

      [download]

      The warning message (without -w swicth or 'use warnings'):

      Empty compile time value given to use lib at C:\Documents and Settings\mt2k\De sktop\testing.pl line 3 

      -------------------------------------
eval reverse@{[lreP
=>q{ tsuJ\{qq},' rehtonA'
,q{\}rekcaH },' tnirp']}[1+1+
1,1-1,1+1,1*1,(1+1)*(1+1)];
-------------------------------------
[reply]
[d/l]
        Mm? 
        my $somewhere;
BEGIN { $somewhere = q(/over/the/rainbow) }

use lib $somewhere;

        [download]

        Makeshifts last the longest.

[reply]
[d/l]

        Oh yeah.. that's funny. Get this - right as soon as the implicit BEGIN (via the use) is parsed inside the currently-being-parsed BEGIN block it is executed. So you're attempting to use $a in your nested BEGIN block prior to defining it. See?

         BEGIN {
   my $a = "c:/";
   BEGIN { require "$a"; import "$a"; }
 }

        [download]

        Fun Fun Fun in the Fluffy Chair

[reply]
[d/l]

In Section Craft