@node lib, lwpcook, less, Module List
@unnumbered manipulate @@INC at compile time


@unnumberedsec NAME

lib - manipulate @@INC at compile time

@unnumberedsec SYNOPSIS

@example
use lib LIST;
@end example

@example
no lib LIST;
@end example

@unnumberedsec DESCRIPTION

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.

@unnumberedsubsec ADDING DIRECTORIES TO @@INC

The parameters to @code{use lib} are added to the start of the perl search
path. Saying

@example
use lib LIST;
@end example

is @emph{almost} the same as saying

@example
BEGIN @{ unshift(@@INC, LIST) @}
@end example

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).

@unnumberedsubsec 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 @code{no lib} statement deletes the @emph{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 @code{no lib}. For example:

@example
no lib qw(:ALL .);
@end example

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).

@unnumberedsubsec RESTORING ORIGINAL @@INC

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

@example
@@INC = @@lib::ORIG_INC;
@end example

@unnumberedsec SEE ALSO

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

@unnumberedsec AUTHOR

Tim Bunce, 2nd June 1995.

