NAME
File::Package - test load a pm and import symbols without eval and $@
misbehavoirs
SYNOPSIS
##########
# Subroutine interface
#
use File::Package qw(is_package_loaded load_package);
$yes = is_package_loaded($package, $program_module);
$error = load_package($program_module);
$error = load_package($program_module, @import);
$error = load_package($program_module, [@package_list]);
$error = load_package($program_module, @import, [@package_list]);
##########
# Class Interface
#
use File::Package;
$yes = is_package_loaded($package, $program_module);
$error = File::Package->load_package($program_module);
$error = File::Package->load_package($program_module, @import);
$error = File::Package->load_package($program_module, [@package_list]);
$error = File::Package->load_package($program_module, @import, [@package_list]);
DESCRIPTION
In a perfect Perl, everything would behave exactly the same running
under "eval". Many times the reason to use an "eval" is the anticipation
that the expression may die. When that happens, a perfect Perl would
have deposited all the output fromm the "warn" and "die" in "$@". Maybe
you have a perfect Perl. However, it is shocking that there are some
Perls on some platforms out in the wild that are mutants and are not
perfect.
A "require" under eval works just fine just to see if a program will
load or not. If working locally, you can simply devise a quick debug
setup and track down the problem. However, when running tests remotely,
on different remote platforms, running continuously unattended where
uptime is important, or any number of situations it is very helpful to
have meaningful error messages when a problem arise.
Thus, the reason to run under "eval" is not only to avoid the "die" but
also to pick up the error message returned by "eval" in "$@". In certain
situations it is extremely critical to obtain reliable error messages
when a failure occurs.
Well, a "eval "require $program_module"" failure returns a reasonble
looking "$@" except for one small thing. Not all the warnings make it to
"$@" at least on one Perl, probably more. And there can be quite a few
warnings when loading a broken program module. It would be nice if
everyone could update to a Perl where the "eval" deposits all the
warnings in "$@". But as the acient proverb says, "If wishes were
horses, beggers would ride.".
One workaround is to catch the warnings with "$SIG{__WARN__}" when
running the "require" under a "eval". This collects all the warnings
which is good. Now when a load fails, the program does not die, it
gracefully collects all the warnings and logs them or ships back.
Now try the "import" under "eval" and pick up the error messages. The
"import" and "eval" is big time "failure to communicate" aka the movie
"Cool Hand Luke". The "import" uses the caller stack to determine where
to stuff the symbols and there is a lot of "Carp" "croak" gyrations such
as making "import" look like "use", trapping "warnings" and "dies". The
"eval" takes off on its own caller stack which to quote President Bush:
"is not helpful".
The "import" uses the "croak" instead of "die" directly or else any
efforts to get meaningfull error messages would be dead on arrival. Perl
is designed so that it is nearly impossible to avoid a die unless
running under a "eval". A workaround is hooking in a "croak" that does
not die and collecting the error messages.
Subroutines
is_package_loaded
$package = is_package_loaded($program_module, $package)
The "is_package_loaded" subroutine determines if the "$package" is
present and the "$progarm_module" loaded. If "$package" is absent, 0 or
'', "$package" is set to the "program_module".
load_package
$error = load_package($program_module, @import, [@package_list]);
The "load_package" subroutine attempts to capture any load problems by
loading the package with a "require " under an eval and capturing all
the "warn" and $@ messages.
If the "$program_module" load is successful, the checks that the
packages in the @package list are present. If @package list is absent,
the "$program_module" uses the "program_module" name as a list of one
package. Although a program module and package have the same name
syntax, they are entirely different. A program module is a file. A
package is a hash of symbols, a symbol table. The Perl convention is
that the names for each are the same which enhances the appearance that
they are the same when in fact they are different. Thus, a program
module may have a single package with a different name or many different
packages.
Finally the "$program_module" subroutine will import the symbols in the
"@import" list. If "@import" is absent "$program_module" subroutine does
not import any symbols; if "@import" is '', all symbols are imported. A
"@import" of 0 usually results in an "$error".
The "$program_module" traps all load errors and all import "Carp::Crock"
errors and returns them in the "$error" string.
One very useful application of the "load_package" subroutine is in test
scripts. If a package does load, it is very helpful that the program
does not die and reports the reason the package did not load. This
information is readily available when loaded at a local site. However,
it the load occurs at a remote site and the load crashes Perl, the
remote tester usually will not have this information readily available.
Other applications include using backup alternative software if a
package does not load. For example if the package 'Compress::Zlib' did
not load, an attempt may be made to use the gzip system command.
BUGS
The "load_package" cannot load program modules whose name contain the
'-' characters. The 'eval' function used to trap the die errors believes
it means subtraction.
REQUIREMENTS
Coming.
DEMONSTRATION
#########
# perl Package.d
###
~~~~~~ Demonstration overview ~~~~~
Perl code begins with the prompt
=>
The selected results from executing the Perl Code follow on the next
lines. For example,
=> 2 + 2
4
~~~~~~ The demonstration follows ~~~~~
=> use File::Package;
=> my $uut = 'File::Package';
=> ##################
=> # Good Load
=> #
=> ###
=> my $error = $uut->load_package( 'File::Basename' )
''
=> $error = $uut->load_package( '_File_::BadLoad' )
'Cannot load _File_::BadLoad
syntax error at E:/User/SoftwareDiamonds/installation/t/File/_File_/BadLoad.pm line 13, near "$FILE "
Global symbol "$FILE" requires explicit package name at E:/User/SoftwareDiamonds/installation/t/File/_File_/BadLoad.pm line 13.
Compilation failed in require at (eval 12) line 1.
Scalar found where operator expected at E:/User/SoftwareDiamonds/installation/t/File/_File_/BadLoad.pm line 13, near "$FILE"
(Missing semicolon on previous line?)
'
=> $uut->load_package( '_File_::BadPackage' )
'# _File_::BadPackage file but package(s) _File_::BadPackage absent.
'
=> $uut->load_package( '_File_::Multi' )
'# _File_::Multi file but package(s) _File_::Multi absent.
'
=> $error = $uut->load_package( '_File_::Hyphen-Test' )
'Cannot load _File_::Hyphen-Test
syntax error at (eval 15) line 1, near "require _File_::Hyphen-"
Warning: Use of "require" without parens is ambiguous at (eval 15) line 1.
'
=> ##################
=> # No &File::Find::find import baseline
=> #
=> ###
=> !defined($main::{'find'})
'1'
=> ##################
=> # Load File::Find, Import &File::Find::find
=> #
=> ###
=> $error = $uut->load_package( 'File::Find', 'find', ['File::Find'] )
''
=> ##################
=> # &File::Find::find imported
=> #
=> ###
=> defined($main::{'find'})
'1'
=> ##################
=> # &File::Find::finddepth not imported
=> #
=> ###
=> !defined($main::{'finddepth'})
'1'
=> ##################
=> # Import error
=> #
=> ###
=> $uut->load_package( 'File::Find', 'Jolly_Green_Giant')
'"Jolly_Green_Giant" is not exported by the File::Find module
Can't continue after import errors at D:/Perl/lib/Exporter/Heavy.pm line 127
Exporter::heavy_export('File::Find', 'main', 'Jolly_Green_Giant') called at D:/Perl/lib/Exporter.pm line 45
Exporter::import('File::Find', 'Jolly_Green_Giant') called at (eval 9) line 81
File::Package::load_package('File::Package', 'File::Find', 'Jolly_Green_Giant') called at E:\User\SoftwareDiamonds\installation\t\File\Package.d line 195
'
=> ##################
=> # &File::Find::finddepth still no imported
=> #
=> ###
=> !defined($main::{'finddepth'})
'1'
=> ##################
=> # Import all File::Find functions
=> #
=> ###
=> $error = $uut->load_package( 'File::Find', '')
''
=> ##################
=> # &File::Find::finddepth imported
=> #
=> ###
=> defined($main::{'finddepth'})
'1'
QUALITY ASSURANCE
Running the test script "package.t" verifies the requirements for this
module.
The <tmake.pl> cover script for Test::STDmaker automatically generated
the "package.t" test script, "package.d" demo script, and
"t::File::Package" STD program module POD, from the "t::File::Package"
program module contents. The "t::File::Package" program module is in the
distribution file File-Package-$VERSION.tar.gz.
NOTES
AUTHOR
The holder of the copyright and maintainer is
<support@SoftwareDiamonds.com>
COPYRIGHT NOTICE
Copyrighted (c) 2002 Software Diamonds
All Rights Reserved
BINDING REQUIREMENTS NOTICE
Binding requirements are indexed with the pharse 'shall[dd]' where dd is
an unique number for each header section. This conforms to standard
federal government practices, 490A (the 3.2.3.6 entry in the STD490A
manpage). In accordance with the License, Software Diamonds is not
liable for any requirement, binding or otherwise.
LICENSE
Software Diamonds permits the redistribution and use in source and
binary forms, with or without modification, provided that the following
conditions are met:
1 Redistributions of source code must retain the above copyright
notice, this list of conditions and the following disclaimer.
2 Redistributions in binary form must reproduce the above copyright
notice, this list of conditions and the following disclaimer in the
documentation and/or other materials provided with the distribution.
SOFTWARE DIAMONDS, http::www.softwarediamonds.com, PROVIDES THIS
SOFTWARE 'AS IS' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT
NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL SOFTWARE
DIAMONDS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
SPECIAL,EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED
TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,DATA, OR
PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING USE
OF THIS SOFTWARE, EVEN IF ADVISED OF NEGLIGENCE OR OTHERWISE) ARISING IN
ANY WAY OUT OF THE POSSIBILITY OF SUCH DAMAGE.
SEE ALSO
Docs::Site_SVD::File_Package
Test::STDmaker
Title Page
Software Version Description
for
File::Package - test load a pm and import symbs without eval and $@ misbehavoirs
Revision: E
Version: 0.06
Date: 2004/04/26
Prepared for: General Public
Prepared by: SoftwareDiamonds.com E<lt>support@SoftwareDiamonds.comE<gt>
Copyright: copyright © 2003 Software Diamonds
Classification: NONE
1.0 SCOPE
This paragraph identifies and provides an overview of the released
files.
1.1 Identification
This release, identified in 3.2, is a collection of Perl modules that
extend the capabilities of the Perl language.
1.2 System overview
One very useful test of the installation of a package is whether or not
the package loaded. If it did not load, the reason it did not load is
helpful diagnostics and may be used to programically (automatically)
take corrective action.
The load_package method attempts to capture any load problems by loading
the package with a "require " under an eval and capturing all the "warn"
and $@ messages. The error messages are returned with a warn instead of
die so that the using program may take the appropriate action such as
reporting the errors back to the author when used in test software or
perhaps falling back on a system 'gzip' command when the
'Compress::Zlib' module fails to load.
1.3 Document overview.
This document releases File::Package version 0.06 providing a
description of the inventory, installation instructions and other
information necessary to utilize and track this release.
3.0 VERSION DESCRIPTION
All file specifications in this SVD use the Unix operating system file
specification.
3.1 Inventory of materials released.
This document releases the file
File-Package-0.06.tar.gz
found at the following repository(s):
http://www.softwarediamonds/packages/
http://www.perl.com/CPAN/authors/id/S/SO/SOFTDIA/
Restrictions regarding duplication and license provisions are as
follows:
Copyright.
copyright © 2003 Software Diamonds
Copyright holder contact.
603 882-0846 E<lt>support@SoftwareDiamonds.comE<gt>
License.
Software Diamonds permits the redistribution and use in source and
binary forms, with or without modification, provided that the
following conditions are met:
1 Redistributions of source code, modified or unmodified must
retain the above copyright notice, this list of conditions and
the following disclaimer.
2 Redistributions in binary form must reproduce the above
copyright notice, this list of conditions and the following
disclaimer in the documentation and/or other materials provided
with the distribution.
SOFTWARE DIAMONDS, http://www.SoftwareDiamonds.com, PROVIDES THIS
SOFTWARE 'AS IS' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING,
BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL
SOFTWARE DIAMONDS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
SPECIAL,EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
USE,DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
OR TORT (INCLUDING USE OF THIS SOFTWARE, EVEN IF ADVISED OF
NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE POSSIBILITY
OF SUCH DAMAGE.
3.2 Inventory of software contents
The content of the released, compressed, archieve file, consists of the
following files:
file version date comment
------------------------------------------------------------ ------- ---------- ------------------------
lib/Docs/Site_SVD/File_Package.pm 0.06 2004/04/26 revised 0.05
MANIFEST 0.06 2004/04/26 generated, replaces 0.05
Makefile.PL 0.06 2004/04/26 generated, replaces 0.05
README 0.06 2004/04/26 generated, replaces 0.05
lib/File/Package.pm 1.16 2004/04/26 revised 1.15
t/File/Package.d 0.03 2004/04/26 revised 0.02
t/File/Package.pm 0.01 2004/04/10 unchanged
t/File/Package.t 0.12 2004/04/26 revised 0.11
t/File/_File_/BadLoad.pm 0.01 2004/04/10 unchanged
t/File/_File_/BadPackage.pm 0.01 2004/04/10 unchanged
t/File/_File_/Hyphen-Test.pm 1.15 2004/04/10 unchanged
t/File/_File_/Multi.pm 1.15 2004/04/10 unchanged
t/File/Test/Tech.pm 1.21 2004/04/26 revised 1.17
t/File/Data/Secs2.pm 1.18 2004/04/26 revised 1.15
t/File/Data/SecsPack.pm 0.03 2004/04/26 new
t/File/Data/Startup.pm 0.03 2004/04/26 new
3.3 Changes
The file names from 0.05 were changed as follows:
return if $file =~ s=lib/File/FileUtil.pm=lib/File/Package.pm=;
return if $file =~ s=t/File/FileUtil/FileUtil.t=t/File/package.t=;
Changes to past revisions are as follows:
Test-TestUtil-0.01
Originated
Test-TestUtil-0.02
Correct failure from Josts Smokehouse"
<Jost.Krieger+smokeback@ruhr-uni-bochum.de> test run
t/Test/TestUtil/TestUtil....Bareword "fspec_dirs" not allowed while
"strict subs" in use at
/net/sunu991/disc1/.cpanplus/5.8.0/build/Test-TestUtil-0.01/blib/lib/Test/TestUtil.pm line 56.
Changed line 56 from
my @dirs = (fspec_dirs) ? $from_package->splitdir( $fspec_dirs ) : ();
to
my @dirs = ($fspec_dirs) ? $from_package->splitdir( $fspec_dirs ) : ();
This error is troublesome since the test passed on my system using
Active Perl under Microsoft NT. It should never have passed. This
error is in a core method, *fspec2fspec*, that changes file
specifications from one operating system to another operating
system. This method has been in service unchanged for some time.
Test-TestUtil-0.03
Correct failure from Josts Smokehouse"
<Jost.Krieger+smokeback@ruhr-uni-bochum.de> test run
PERL_DL_NONLAZY=1 /usr/local/perl/bin/perl "-MExtUtils::Command::MM"
"-e" "test_harness(0, 'blib/lib', 'blib/arch')"
t/Test/TestUtil/TestUtil.t t/Test/TestUtil/TestUtil....# Test 18
got: '$VAR1 = ''; ' (t/Test/TestUtil/TestUtil.t at line 540 fail
#17) # Expected: '$VAR1 = '\\=head1 Title Page
The *pm2datah* method is not returning any data for Test 18. This
will also cause the test of *pm2data*, test 19 to fail. The
*pm2datah* is searching for the string "\n__DATA__\n".
The "\n" character on Perl is a logical end of line character
sequence. The "\n" end of line is different on Mr. Smokehouse's Unix
operating system than on my Windows NT operating system. The test
file was created under MSWin32 and uses a MSWin32 "\n". Under UNIX,
*pm2datah* method will look for the Unix "\n" and there will not be
any.
Changed "\n__DATA__\n" to /[\012\015]__DATA__/.
During the clean-up for CPAN, broke the *format_hash_table* method
for tables in hash of hash format. Fixed the break, added test 29 to
the *t/Test/TestUtil/TestUtil.t* test script for this feature, and
added a discusssion of this feature in POD discription for
*format_hash_table*
Test-TestUtil-0.04
item our old friend visits again - DOS and UNIX text file
incompatibility
This impacts other modules. We have to examine all modules for this
portability defect and correct any found defects.
Correct failure from Josts Smokehouse"
<Jost.Krieger+smokeback@ruhr-uni-bochum.de> and Kingpin
<mthurn@carbon> test runs.
On Mr. Smokehouse's run email the got: VAR1 clearly showed extra
white space line that is not present in the expected: VAR1. In Mr.
Kingpin's run the got: VAR1 and expected: VAR1 look visually the
same. However, the Unix found a difference(s) and failed the test.
For Mr. Smokehouse's run:
PERL_DL_NONLAZY=1 /usr/local/bin/perl "-MExtUtils::Command::MM" "-e"
"test_harness(0, 'blib/lib', 'blib/arch')"
t/Test/TestUtil/TestUtil.t t/Test/TestUtil/TestUtil....NOK 18# Test
18 got: '$VAR1 = '\\=head1 Title Page
Software Version Description
for
File::Package - test load a pm and import symbs without eval and $@ misbehavoirs
Revision: E
[snip]
(t/Test/TestUtil/TestUtil.t at line 565 fail #17) # Expected: '$VAR1
= '\\=head1 Title Page
Software Version Description
for
File::Package - test load a pm and import symbs without eval and $@ misbehavoirs
What we have before, was a totally "failure to communicate." aka
Cool Hand Luke. VAR1 was empty. Now VAR1 has something. It is not
completely dead. One probable cause is the Unix operating system
must be producing two Unix \012 new lines for a Microsoft single
newline \015\012. Without being able to examine the test with a
debugger, the only way to verify this is to provide the fix and see
if the problem goes away when this great group of testers try for
the fourth time.
Revised *fin* method to take a handle, change *pm2datah* method
handle, *$fh*, to binary by adding a *binmode $fh* statement, and
pass the actual thru the *fin* method for test 18.
Use *fin($fh)* to read in the data for *pm2data*, test 19 Unit Under
Test (UUT), instead of using the raw file handle.
The *fin* method takes any \015\012 combination and changes it into
the logical Perl new line, *"\n"*, for the current operating system.
File-FileUtil-0.01
* At 02:44 AM 6/14/2003 +0200, Max Maischein wrote: A second thing
that I would like you to reconsider is the naming of
"Test::TestUtil" respectively "Test::Tech" - neither of those is
descriptive of what the routines actually do or what the module
implements. I would recommend renaming them to something closer
to your other modules, maybe "Test::SVDMaker::Util" and
"Test::SVDMaker::Tech", as some routines do not seem to be
specific to the Test::-suite but rather general
(format_array_table). Some parts (the "scrub" routines) might
even better live in another module namespace,
"Test::Util::ScrubData" or something like that.
Broke away all the file related methods from Test::TestUtil and
created this module File::FileUtil so the module name is more
descriptive of the methods within the module.
* Broke the smart nl code out of the fin method and made it is own
separate method, smart_nl method.
At 02:44 AM 6/14/2003 +0200, Max Maischein wrote: Perl, as Perl
already does smart newline handling, (even though with the
advent of 5.8 even Unix-people have to learn the word "binmode"
now :-))
The only place where I see Perl does smart newline handling is
the crlf IO displine introduce in Perl 5.6. The File::FileUtil
has a use 5.001 so that 5.6 Perl built-ins cannot be used. Added
comment to smart_nl that for users with 5.6 Perl that it may be
better to use the built-in crlf IO discipline.
* For the load_package method that uses a eval "require $package"
to load the package, the $@ does not capture all the warnings
and error messages, at least not with ActiveState Perl. Added
code the captures also the warnings, by temporaily reassigning
$SIG(__WARN__), and added these to the $@ error messages.
* Added two new tests to verify the NOGO paths for the for the
load_package method. One tests for load module failure looking
for all the possilbe information on why the module did not load.
The other verifies that the vocabulary is present after the
loading the module. This information is very helpful when you
must remote debug a load failure from CPAN testing whose is
running on a different platform.
File-FileUtil-0.02
Added the method *hex_dump*.
File-FileUtil-0.03
test_lib2inc
Returns to parent directory of the first t directory going up
from the test script instead of the t directory.
find_t_roots
Added the function find_t_roots that returns the parent
directory of all the directories in @INC
File-Package-0.01
Removed the methods for loading a program module with the same name
from the "File::FileUtil" module to their own module "File::Package"
module. The module name is now much more descriptive of the routines
in the module.
File-Package-0.02
Replace the obsolete "File::FileUtil" with File::Packgage in the
test script "t\File\package.t".
File-Package-0.03
Added subroutine interfaces.
Added @import input to load_packages method
File-Package-0.04
Upgraded the 'tlib\Test\Tech' and changed the name of
'tlib\Data\strify' to 'tlib\Data\Secs2'. The new name is more
self-explanatory.
File-Package-0.05
The lastest build of Test::STDmaker expects the test library in the
same directory as the test script. Coordiated with the lastest
Test::STDmaker by moving the test library from tlib to t/File, the
same directory as the test script and deleting the test library
File::TestPath program module.
File-Package-0.06
Added "Carp::longmess", that dumps the call stack, to the
Carp::croak trap function.
File-Package-0.07
Expanded the description.
Under the Perl 5.6, Microsoft distribute, "Carp" program module,
"import" sends warings out using "&Carp::carp" function as well as
"Carp::croak" function. Adjust to also pick up these messages.
3.4 Adaptation data.
This installation requires that the installation site has the Perl
programming language installed. There are no other additional
requirements or tailoring needed of configurations files, adaptation
data or other software needed for this installation particular to any
installation site.
3.5 Related documents.
There are no related documents needed for the installation and test of
this release.
3.6 Installation instructions.
Instructions for installation, installation tests and installation
support are as follows:
Installation Instructions.
To installed the release file, use the CPAN module pr PPM module in
the Perl release or the INSTALL.PL script at the following web site:
http://packages.SoftwareDiamonds.com
Follow the instructions for the the chosen installation software.
If all else fails, the file may be manually installed. Enter one of
the following repositories in a web browser:
http://www.softwarediamonds/packages/
http://www.perl.com/CPAN/authors/id/S/SO/SOFTDIA/
Right click on 'File-Package-0.06.tar.gz' and download to a
temporary installation directory. Enter the following where $make is
'nmake' for microsoft windows; otherwise 'make'.
gunzip File-Package-0.06.tar.gz
tar -xf File-Package-0.06.tar
perl Makefile.PL
$make test
$make install
On Microsoft operating system, nmake, tar, and gunzip must be in the
exeuction path. If tar and gunzip are not install, download and
install unxutils from
http://packages.softwarediamonds.com
Prerequistes.
None.
Security, privacy, or safety precautions.
None.
Installation Tests.
Most Perl installation software will run the following test
script(s) as part of the installation:
t/File/Package.t
Installation support.
If there are installation problems or questions with the
installation contact
603 882-0846 E<lt>support@SoftwareDiamonds.comE<gt>
3.7 Possible problems and known errors
There is still much work needed to ensure the quality of this module as
follows:
* State the functional requirements for each method including not only
the GO paths but also what to expect for the NOGO paths
* All the tests are GO path tests. Should add NOGO tests.
* Add the requirements addressed as *# R: * comment to the tests
4.0 NOTES
The following are useful acronyms:
.d extension for a Perl demo script file
.pm extension for a Perl Library Module
.t extension for a Perl test script file
POD Plain Old Documentation
2.0 SEE ALSO
File::Package
Docs::US_DOD::SVD