=head1 NAME
-perlfaq1 - General Questions About Perl ($Revision: 9671 $)
+perlfaq1 - General Questions About Perl ($Revision: 9681 $)
=head1 DESCRIPTION
=item *
-No one is actively supporting perl4.x. Five years ago it was a dead
+No one is actively supporting Perl 4. Five years ago it was a dead
camel carcass (according to this document). Now it's barely a skeleton
as its whitewashed bones have fractured or eroded.
=item *
-There is no perl6.x for the next couple of years. Stay tuned, but don't
+There is no Perl 6 for the next couple of years. Stay tuned, but don't
worry that you'll have to change major versions of Perl soon (i.e. before
2008).
=back
-=head2 What are perl4, perl5, or perl6?
+=head2 What are Perl 4, Perl 5, or Perl 6?
(contributed by brian d foy)
-In short, perl4 is the past, perl5 is the present, and perl6 is the
+In short, Pelr 4 is the past, Perl 5 is the present, and Perl 6 is the
future.
-The number after perl (i.e. the 5 after perl5) is the major release
+The number after perl (i.e. the 5 after Perl 5) is the major release
of the perl interpreter as well as the version of the language. Each
major version has significant differences that earlier versions cannot
support.
-The current major release of Perl is perl5, and was released in 1994.
+The current major release of Perl is Perl 5, and was released in 1994.
It can run scripts from the previous major release, perl4 (March 1991),
but has significant differences. It introduced the concept of references,
-complex data structures, and modules. The perl5 interpreter was a
+complex data structures, and modules. The Perl 5 interpreter was a
complete re-write of the previous perl sources.
-Perl6 is the next major version of Perl, but it's still in development
+Perl 6 is the next major version of Perl, but it's still in development
in both its syntax and design. The work started in 2002 and is still
ongoing. Many of the most interesting features have shown up in the
-latest versions of perl5, and some perl5 modules allow you to use some
-perl6 syntax in your programs. You can learn more about perl6 at
+latest versions of Perl 5, and some Perl 5 modules allow you to use some
+Perl 6 syntax in your programs. You can learn more about Perl 6 at
http://dev.perl.org/perl6/ .
See L<perlhist> for a history of Perl revisions.
able to just keep using Perl 5 with Parrot, the virtual machine which
will compile and run Perl 6 bytecode.
-=head2 What is perl6?
+=head2 What is Perl 6?
At The Second O'Reilly Open Source Software Convention, Larry Wall
-announced Perl6 development would begin in earnest. Perl6 was an oft
+announced Perl 6 development would begin in earnest. Perl 6 was an oft
used term for Chip Salzenberg's project to rewrite Perl in C++ named
Topaz. However, Topaz provided valuable insights to the next version
of Perl and its implementation, but was ultimately abandoned.
-If you want to learn more about Perl6, or have a desire to help in
-the crusade to make Perl a better place then peruse the Perl6 developers
+If you want to learn more about Perl 6, or have a desire to help in
+the crusade to make Perl a better place then peruse the Perl 6 developers
page at http://dev.perl.org/perl6/ and get involved.
-Perl6 is not scheduled for release yet, and Perl5 will still be supported
-for quite awhile after its release. Do not wait for Perl6 to do whatever
+Perl 6 is not scheduled for release yet, and Perl 5 will still be supported
+for quite awhile after its release. Do not wait for Perl 6 to do whatever
you need to do.
"We're really serious about reinventing everything that needs reinventing."
Larry and the Perl development team occasionally make changes to the
internal core of the language, but all possible efforts are made toward
-backward compatibility. While not quite all perl4 scripts run flawlessly
-under perl5, an update to perl should nearly never invalidate a program
+backward compatibility. While not quite all Perl 4 scripts run flawlessly
+under Perl 5, an update to perl should nearly never invalidate a program
written for an earlier version of perl (barring accidental bug fixes
and the rare new keyword).
=head1 REVISION
-Revision: $Revision: 9671 $
+Revision: $Revision: 9681 $
-Date: $Date: 2007-06-23 18:38:20 +0200 (Sat, 23 Jun 2007) $
+Date: $Date: 2007-06-26 01:36:56 +0200 (Tue, 26 Jun 2007) $
See L<perlfaq> for source control details and availability.
=head1 NAME
-perlfaq4 - Data Manipulation ($Revision: 9491 $)
+perlfaq4 - Data Manipulation ($Revision: 9681 $)
=head1 DESCRIPTION
$hash{'d'} is false
defined $hash{'d'} is true
defined $hash{'a'} is true
- exists $hash{'a'} is true (Perl5 only)
+ exists $hash{'a'} is true (Perl 5 only)
grep ($_ eq 'a', keys %hash) is true
If you now say
$hash{'d'} is false
defined $hash{'d'} is true
defined $hash{'a'} is FALSE
- exists $hash{'a'} is true (Perl5 only)
+ exists $hash{'a'} is true (Perl 5 only)
grep ($_ eq 'a', keys %hash) is true
Notice the last two: you have an undef value, but a defined key!
$hash{'d'} is false
defined $hash{'d'} is true
defined $hash{'a'} is false
- exists $hash{'a'} is FALSE (Perl5 only)
+ exists $hash{'a'} is FALSE (Perl 5 only)
grep ($_ eq 'a', keys %hash) is FALSE
See, the whole entry is gone!
=head1 REVISION
-Revision: $Revision: 9491 $
+Revision: $Revision: 9681 $
-Date: $Date: 2007-05-02 13:14:13 +0200 (Wed, 02 May 2007) $
+Date: $Date: 2007-06-26 01:36:56 +0200 (Tue, 26 Jun 2007) $
See L<perlfaq> for source control details and availability.
projects / platform / upstream / perl.git / commitdiff