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perlman:lib:lib

by root (Scribe)
on Dec 23, 1999 at 00:49 UTC ( #1142=perlfunc: print w/ replies, xml ) Need Help??

lib:lib

See the current Perl documentation for lib:lib.

Here is our local, out-dated (pre-5.6) version:


lib - manipulate @INC at compile time



    use lib LIST;

    no lib LIST;



This is a small simple module which simplifies the manipulation of @INC at compile time.

It is typically used to add extra directories to perl's search path so that later use or require statements will find modules which are not located on perl's default search path.


ADDING DIRECTORIES TO @INC

The parameters to use lib are added to the start of the perl search path. Saying

    use lib LIST;

is almost the same as saying

    BEGIN { unshift(@INC, LIST) }

For each directory in LIST (called $dir here) the lib module also checks to see if a directory called $dir/$archname/auto exists. If so the $dir/$archname directory is assumed to be a corresponding architecture specific directory and is added to @INC in front of $dir.

If LIST includes both $dir and $dir/$archname then $dir/$archname will be added to @INC twice (if $dir/$archname/auto exists).


DELETING DIRECTORIES FROM @INC

You should normally only add directories to @INC. If you need to delete directories from @INC take care to only delete those which you added yourself or which you are certain are not needed by other modules in your script. Other modules may have added directories which they need for correct operation.

By default the no lib statement deletes the first instance of each named directory from @INC. To delete multiple instances of the same name from @INC you can specify the name multiple times.

To delete all instances of all the specified names from @INC you can specify ':ALL' as the first parameter of no lib. For example:

    no lib qw(:ALL .);

For each directory in LIST (called $dir here) the lib module also checks to see if a directory called $dir/$archname/auto exists. If so the $dir/$archname directory is assumed to be a corresponding architecture specific directory and is also deleted from @INC.

If LIST includes both $dir and $dir/$archname then $dir/$archname will be deleted from @INC twice (if $dir/$archname/auto exists).


RESTORING ORIGINAL @INC

When the lib module is first loaded it records the current value of @INC in an array @lib::ORIG_INC. To restore @INC to that value you can say

    @INC = @lib::ORIG_INC;


SEE ALSO

FindBin - optional module which deals with paths relative to the source file.


AUTHOR

Tim Bunce, 2nd June 1995.


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