=head1 NAME
-perlfaq3 - Programming Tools ($Revision: 1.15 $, $Date: 2002/02/11 19:29:52 $)
+perlfaq3 - Programming Tools ($Revision: 1.31 $, $Date: 2003/01/03 20:10:11 $)
=head1 DESCRIPTION
from the source distribution is simplistic and uninteresting, but
may still be what you want.
+=head2 How do I find which modules are installed on my system?
+
+You can use the ExtUtils::Installed module to show all
+installed distributions, although it can take awhile to do
+its magic. The standard library which comes with Perl just
+shows up as "Perl" (although you can get those with
+Mod::CoreList).
+
+ use ExtUtils::Installed;
+
+ my $inst = ExtUtils::Installed->new();
+ my @modules = $inst->modules();
+
+If you want a list of all of the Perl module filenames, you
+can use File::Find::Rule.
+
+ use File::Find::Rule;
+
+ my @files = File::Find::Rule->file()->name( '*.pm' )->in( @INC );
+
+If you do not have that module, you can do the same thing
+with File::Find which is part of the standard library.
+
+ use File::Find;
+ my @files;
+
+ find sub { push @files, $File::Find::name if -f _ && /\.pm$/ },
+ @INC;
+
+ print join "\n", @files;
+
+If you simply need to quickly check to see if a module is
+available, you can check for its documentation. If you can
+read the documentation the module is most likely installed.
+If you cannot read the documentation, the module might not
+have any (in rare cases).
+
+ prompt% perldoc Module::Name
+
+You can also try to include the module in a one-liner to see if
+perl finds it.
+
+ perl -MModule::Name -e1
+
=head2 How do I debug my Perl programs?
-Have you tried C<use warnings> or used C<-w>? They enable warnings
+Have you tried C<use warnings> or used C<-w>? They enable warnings
to detect dubious practices.
Have you tried C<use strict>? It prevents you from using symbolic
=head2 How do I profile my Perl programs?
You should get the Devel::DProf module from the standard distribution
-(or separately on CPAN) and also use Benchmark.pm from the standard
-distribution. The Benchmark module lets you time specific portions of
-your code, while Devel::DProf gives detailed breakdowns of where your
+(or separately on CPAN) and also use Benchmark.pm from the standard
+distribution. The Benchmark module lets you time specific portions of
+your code, while Devel::DProf gives detailed breakdowns of where your
code spends its time.
Here's a sample use of Benchmark:
=head2 How do I cross-reference my Perl programs?
-The B::Xref module can be used to generate cross-reference reports
+The B::Xref module can be used to generate cross-reference reports
for Perl programs.
perl -MO=Xref[,OPTIONS] scriptname.plx
as it were. A more complete example, with comments, can be found at
http://www.cpan.org/authors/id/TOMC/scripts/toms.exrc.gz
-The a2ps http://www-inf.enst.fr/%7Edemaille/a2ps/black+white.ps does
+The a2ps http://www-inf.enst.fr/%7Edemaille/a2ps/black+white.ps.gz does
lots of things related to generating nicely printed output of
-documents, as does enscript at http://people.ssh.fi/mtr/genscript/.
+documents, as does enscript at http://people.ssh.fi/mtr/genscript/ .
=head2 Is there a ctags for Perl?
ActiveState's cross-platform (as of April 2001 Windows and Linux),
multi-language IDE has Perl support, including a regular expression
debugger and remote debugging
-(http://www.ActiveState.com/Products/Komodo/index.html). (Visual
+( http://www.ActiveState.com/Products/Komodo/index.html ). (Visual
Perl, a Visual Studio.NET plug-in is currently (early 2001) in beta
-(http://www.ActiveState.com/Products/VisualPerl/index.html)).
+( http://www.ActiveState.com/Products/VisualPerl/index.html )).
=item The Object System
-(http://www.castlelink.co.uk/object_system/) is a Perl web
+( http://www.castlelink.co.uk/object_system/ ) is a Perl web
applications development IDE, apparently for any platform
that runs Perl.
=item PerlBuilder
-(http://www.solutionsoft.com/perl.htm) is an integrated development
+( http://www.solutionsoft.com/perl.htm ) is an integrated development
environment for Windows that supports Perl development.
=item visiPerl+
( http://helpconsulting.net/visiperl/ )
From Help Consulting, for Windows.
-=back
-
-For Windows there's also the
-
-=over 4
-
-=item CodeMagicCD
+=item OptiPerl
-( http://www.codemagiccd.com/ ) Collection of various programming
-tools for Windows: Perl (5.005_03), TclTk, Python, GNU programming
-tools, REBOL, wxWindows toolkit, the MinGW GNU C/C++ compiler, DJGPP
-GNU C/C++ compiler, Cint C interpreter, YaBasic.
+( http://www.optiperl.com/ ) is a Windows IDE with simulated CGI
+environment, including debugger and syntax highlighting editor.
=back
information, although some allow you to save files as "Text
Only". You can also download text editors designed
specifically for programming, such as Textpad
-(http://www.textpad.com/) and UltraEdit
-(http://www.ultraedit.com), among others.
+( http://www.textpad.com/ ) and UltraEdit
+( http://www.ultraedit.com/ ), among others.
If you are using MacOS, the same concerns apply. MacPerl
(for Classic environments) comes with a simple editor.
-Popular external editors are BBEdit (http://www.bbedit.com)
-or Alpha (http://alpha.olm.net/). MacOS X users can use Unix
-editors as well.
+Popular external editors are BBEdit ( http://www.bbedit.com/ )
+or Alpha ( http://www.kelehers.org/alpha/ ). MacOS X users can
+use Unix editors as well.
=over 4
=item MicroEMACS
-http://members.nbci.com/uemacs/
+http://www.microemacs.de/
=item XEmacs
http://www.xemacs.org/Download/index.html
+=item Jed
+
+http://space.mit.edu/~davis/jed/
+
=back
or a vi clone such as
=item Vile
-http://vile.cx/
+http://dickey.his.com/vile/vile.html
=item Vim
http://www.vim.org/
-win32: http://www.cs.vu.nl/%7Etmgil/vi.html
-
=back
For vi lovers in general, Windows or elsewhere:
-http://www.thomer.com/thomer/vi/vi.html.
-nvi (http://www.bostic.com/vi/, available from CPAN in src/misc/) is
+ http://www.thomer.com/thomer/vi/vi.html
+
+nvi ( http://www.bostic.com/vi/ , available from CPAN in src/misc/) is
yet another vi clone, unfortunately not available for Windows, but in
UNIX platforms you might be interested in trying it out, firstly because
strictly speaking it is not a vi clone, it is the real vi, or the new
There is also a toyedit Text widget based editor written in Perl
that is distributed with the Tk module on CPAN. The ptkdb
-(http://world.std.com/~aep/ptkdb/) is a Perl/tk based debugger that
+( http://world.std.com/~aep/ptkdb/ ) is a Perl/tk based debugger that
acts as a development environment of sorts. Perl Composer
-(http://perlcomposer.sourceforge.net/vperl.html) is an IDE for Perl/Tk
+( http://perlcomposer.sourceforge.net/ ) is an IDE for Perl/Tk
GUI creation.
In addition to an editor/IDE you might be interested in a more
=item Bash
-from the Cygwin package (http://sources.redhat.com/cygwin/)
+from the Cygwin package ( http://sources.redhat.com/cygwin/ )
=item Ksh
-from the MKS Toolkit (http://www.mks.com/), or the Bourne shell of
-the U/WIN environment (http://www.research.att.com/sw/tools/uwin/)
+from the MKS Toolkit ( http://www.mks.com/ ), or the Bourne shell of
+the U/WIN environment ( http://www.research.att.com/sw/tools/uwin/ )
=item Tcsh
-ftp://ftp.astron.com/pub/tcsh/, see also
+ftp://ftp.astron.com/pub/tcsh/ , see also
http://www.primate.wisc.edu/software/csh-tcsh-book/
=item Zsh
-ftp://ftp.blarg.net/users/amol/zsh/, see also http://www.zsh.org/
+ftp://ftp.blarg.net/users/amol/zsh/ , see also http://www.zsh.org/
=back
=item BBEdit and BBEdit Lite
are text editors for Mac OS that have a Perl sensitivity mode
-(http://web.barebones.com/).
+( http://web.barebones.com/ ).
=item Alpha
is an editor, written and extensible in Tcl, that nonetheless has
built in support for several popular markup and programming languages
-including Perl and HTML (http://alpha.olm.net/).
+including Perl and HTML ( http://alpha.olm.net/ ).
=back
Pepper and Pe are programming language sensitive text editors for Mac
-OS X and BeOS respectively (http://www.hekkelman.com/).
+OS X and BeOS respectively ( http://www.hekkelman.com/ ).
=head2 Where can I get Perl macros for vi?
see http://www.cpan.org/authors/Tom_Christiansen/scripts/toms.exrc.gz ,
the standard benchmark file for vi emulators. The file runs best with nvi,
the current version of vi out of Berkeley, which incidentally can be built
-with an embedded Perl interpreter--see http://www.cpan.org/src/misc.
+with an embedded Perl interpreter--see http://www.cpan.org/src/misc/ .
=head2 Where can I get perl-mode for emacs?
The Curses module from CPAN provides a dynamically loadable object
module interface to a curses library. A small demo can be found at the
-directory http://www.cpan.org/authors/Tom_Christiansen/scripts/rep;
+directory http://www.cpan.org/authors/Tom_Christiansen/scripts/rep.gz ;
this program repeats a command and updates the screen as needed, rendering
B<rep ps axu> similar to B<top>.
When the files you're processing are small, it doesn't much matter which
way you do it, but it makes a huge difference when they start getting
-larger.
+larger.
=item * Use map and grep selectively
For "big" data stores (i.e. ones that exceed available memory) consider
using one of the DB modules to store it on disk instead of in RAM. This
-will incur a penalty in access time, but that's probably better that
+will incur a penalty in access time, but that's probably better than
causing your hard disk to thrash due to massive swapping.
=back
-=head2 Is it unsafe to return a pointer to local data?
+=head2 Is it safe to return a reference to local or lexical data?
-No, Perl's garbage collection system takes care of this.
+Yes. Perl's garbage collection system takes care of this so
+everything works out right.
sub makeone {
my @a = ( 1 .. 10 );
return \@a;
}
- for $i ( 1 .. 10 ) {
+ for ( 1 .. 10 ) {
push @many, makeone();
}
=head2 How can I free an array or hash so my program shrinks?
-You can't. On most operating systems, memory allocated to a program
-can never be returned to the system. That's why long-running programs
-sometimes re-exec themselves. Some operating systems (notably,
-FreeBSD and Linux) allegedly reclaim large chunks of memory that is no
-longer used, but it doesn't appear to happen with Perl (yet). The Mac
-appears to be the only platform that will reliably (albeit, slowly)
-return memory to the OS.
-
-We've had reports that on Linux (Redhat 5.1) on Intel, C<undef
-$scalar> will return memory to the system, while on Solaris 2.6 it
-won't. In general, try it yourself and see.
+You usually can't. On most operating systems, memory
+allocated to a program can never be returned to the system.
+That's why long-running programs sometimes re-exec
+themselves. Some operating systems (notably, systems that
+use mmap(2) for allocating large chunks of memory) can
+reclaim memory that is no longer used, but on such systems,
+perl must be configured and compiled to use the OS's malloc,
+not perl's.
However, judicious use of my() on your variables will help make sure
that they go out of scope so that Perl can free up that space for
There are two popular ways to avoid this overhead. One solution
involves running the Apache HTTP server (available from
-http://www.apache.org/) with either of the mod_perl or mod_fastcgi
+http://www.apache.org/ ) with either of the mod_perl or mod_fastcgi
plugin modules.
With mod_perl and the Apache::Registry module (distributed with
http://perl.apache.org/
With the FCGI module (from CPAN) and the mod_fastcgi
-module (available from http://www.fastcgi.com/) each of your Perl
+module (available from http://www.fastcgi.com/ ) each of your Perl
programs becomes a permanent CGI daemon process.
Both of these solutions can have far-reaching effects on your system
of difficulty to people wanting to get at your code, but none can
definitively conceal it (true of every language, not just Perl).
+It is very easy to recover the source of Perl programs. You simply
+feed the program to the perl interpreter and use the modules in
+the B:: hierarchy. The B::Deparse module should be able to
+defeat most attempts to hide source. Again, this is not
+unique to Perl.
+
If you're concerned about people profiting from your code, then the
bottom line is that nothing but a restrictive license will give you
legal security. License your software and pepper it with threatening
try http://www.perldoc.com/ , but consider upgrading your perl.)
A good book on OO on Perl is the "Object-Oriented Perl"
-by Damian Conway from Manning Publications,
+by Damian Conway from Manning Publications,
http://www.manning.com/Conway/index.html
=head2 Where can I learn about linking C with Perl? [h2xs, xsubpp]
projects / p5sagit/p5-mst-13.2.git / blobdiff