Learning Perl Objects, References amp;amp; Modules [Electronic resources] نسخه متنی

12.1 Sample Function-Oriented Interface: File::Basename

To understand what happens with
use, look at one of the many modules included with
a normal Perl distribution: File::Basename. This
module parses file specifications into useful pieces in a mostly
portable manner. The default usage:

use File::Basename;

introduces three
subroutines, fileparse,
basename, and
dirname,[1]
into the current package: typically, main in the
main part of your program. From this point forward, within this
package, you can say: [2]

[1] As well as a utility
routine, fileparse_set_fstype.

[2] The new symbols are available
for all code compiled in the current package from this point on,
whether it's in this same file or not. However,
these symbols won't be available in a different
package.

my $basename = basename($some_full_path);
my $dirname = dirname($some_full_path);

as if you had written the basename and
dirname subroutines yourself, or (nearly) as if
they were built-in Perl functions.[3]

[3] These routines
pick out the filename and the directory parts of a pathname. For
example, if $some_full_path were
D:\Projects\Island Rescue\plan
7.rtf (presumably, the program is running on a
Windows machine), the basename would be
plan 7.rtf and the
dirname would be D:\Projects\Island
Rescue.

However, suppose you already had a
dirname subroutine? You've now
overwritten it with the definition provided by
File::Basename! If you had turned on warnings,
you'd see a message stating that, but otherwise,
Perl really doesn't care.