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As the title suggests, this book is a complete reference to the Perl
programming language. As such, it includes details of everything you
want to know about statements, expressions, functions, and regular
expressions within Perl. Some highlights of the book include the
creation of useful packages and modules, using Perl on the command
line and Tk as a cross-platform user interface solution. There are
also several chapters dedicated to the design and use of the supported
data structures within Perl, and to the processes available for
accessing external data structures and databases.
Interprocess communication, either between processes on the same
machine or between processes on different machines, is also a topic
for discussion. The former is handled by a number of tricks and some
system-dependent features. For the latter machine communication, you
can use network sockets. An alternative solution to the problems of
processing between multiple processes is to use threads, which are
small, "lightweight" execution sequences that are still owned in their
entirety by their parent process, and we also look at how threads can
be used to solve these problems.
A large portion of the book is given over to the process of getting
inside Perl. We examine how Perl works as it parses a Perl script and
how that process can be modified with compiler pragmas. Then we move
on to the process of extending Perl by writing an interface between
Perl and a C function. This allows Perl to use and access an unlimited
number of extensions and enhancements to the core Perl language. You
can also do the reverse. You can embed the Perl interpreter into a C
program, allowing you to use the advanced features of Perl within a C
program. You could even build the interpreter into an application to
provide a built-in scripting language.
A recent development in the Perl interpreter has allowed the creation
of a Perl compiler (which is in itself a bit of a misnomer; see
Chapter 1 for details). With the compiler you can do many things,
including produce some detailed output on the real structure and
execution path that your script takes. One of the most significant and
useful features, though, is that you can take a Perl script and
produce a stand-alone executable program.
Perl is also a good cross-platform development tool. See Chapter 1
for a list of some of the platforms that Perl has been ported to. We
take a close look at the three main platforms-Unix, Windows, and
MacOS-and how they differ, before taking a more generalized view of
how to program with Perl in a cross-platform world and ensure the
cross-platform compatibility.
Finally, the appendixes provide a quick and detailed reference to
the Perl functions, error messages, and the standard Perl library that
comes with every distribution. Of course, even with the best
intentions, it's possible to have forgotten some element, or not to
have gone through a particular element to a deep enough degree,
although I hope this won't be the case for most readers.
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I haven't targeted the book at any specific group of Perl users. To
put it simply, if you program in Perl, you will find this book
useful. As a reference, most people should find it useful to keep on
the desk or the shelf just as a quick means of looking up a particular
function or feature. For learners and expert users alike, the
information in this book will be invaluable.
You should also find the book useful if you want to know how to do a
particular task in Perl, since you'll also find working, real-world
examples of the different features of Perl within the book. If you are
looking for more examples, you might want to look at Perl Annotated
Archives, which contains over 100 scripts to solve a myriad of
different problems.
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Pick it up, look up the feature you want to get
more information on from the contents or the index, and read! The
scripts and script fragments included in the book should all work
without modification on your machine. Be aware though that not all
platforms support all Perl features. Use Chapters 21 through 24 if you
are unsure of a feature.
If you want purely reference information-that is, you want to look up
the arguments and return values to a function-then use the appendixes
at the back. For discussion, examples, and detailed information on a
particular feature, use one of the earlier chapters. You should find
references between the chapters and appendixes in both directions to
help you get more information.
The bulk of the book covers the core version of Perl as it is
supported and developed under Unix. See Chapter 21 for details on
using Perl on the Unix platform. If you are programming under Windows
or MacOS, then please read Chapter 22 or 23, respectively, for details
on how to obtain, compile, and program Perl on those two platforms.
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