diff options
Diffstat (limited to 'pod/perlmod.pod')
| -rw-r--r-- | pod/perlmod.pod | 30 |
1 files changed, 16 insertions, 14 deletions
diff --git a/pod/perlmod.pod b/pod/perlmod.pod index d804b1e4ed..dc825d6386 100644 --- a/pod/perlmod.pod +++ b/pod/perlmod.pod @@ -6,8 +6,10 @@ perlmod - Perl modules (packages) =head2 Packages -Perl provides a mechanism for alternate namespaces to protect packages -from stomping on each others variables. By default, a Perl script starts +Perl provides a mechanism for alternative namespaces to protect packages +from stomping on each others variables. In fact, apart from certain magical +variables, there's really no such thing as a global variable in Perl. +By default, a Perl script starts compiling into the package known as C<main>. You can switch namespaces using the C<package> declaration. The scope of the package declaration is from the declaration itself to the end of the enclosing block (the same @@ -34,11 +36,11 @@ It would treat package C<INNER> as a totally separate global package. Only identifiers starting with letters (or underscore) are stored in a package's symbol table. All other symbols are kept in package C<main>. -In addition, the identifiers STDIN, STDOUT, STDERR, C<ARGV>, +In addition, the identifiers STDIN, STDOUT, STDERR, ARGV, ARGVOUT, ENV, INC and SIG are forced to be in package C<main>, even when used for other purposes than their built-in one. Note also that, if you have a package called C<m>, C<s> or C<y>, then you can't use -the qualified form of an identifier since it will be interpreted instead +the qualified form of an identifier because it will be interpreted instead as a pattern match, a substitution, or a translation. (Variables beginning with underscore used to be forced into package @@ -47,7 +49,7 @@ to use leading underscore to indicate private variables and method names.) Eval()ed strings are compiled in the package in which the eval() was compiled. (Assignments to C<$SIG{}>, however, assume the signal -handler specified is in the C<main. package. Qualify the signal handler +handler specified is in the C<main> package. Qualify the signal handler name if you wish to have a signal handler in a package.) For an example, examine F<perldb.pl> in the Perl library. It initially switches to the C<DB> package so that the debugger doesn't interfere with variables @@ -111,7 +113,7 @@ i.e., *dick = *richard; -causes variables, subroutines and filehandles accessible via the +causes variables, subroutines and file handles accessible via the identifier C<richard> to also be accessible via the symbol C<dick>. If you only want to alias a particular variable or subroutine, you can assign a reference instead: @@ -139,7 +141,7 @@ An C<END> subroutine is executed as late as possible, that is, when the interpreter is being exited, even if it is exiting as a result of a die() function. (But not if it's is being blown out of the water by a signal--you have to trap that yourself (if you can).) You may have -multiple C<END> blocks within a file--they wil execute in reverse +multiple C<END> blocks within a file--they will execute in reverse order of definition; that is: last in, first out (LIFO). Note that when you use the B<-n> and B<-p> switches to Perl, C<BEGIN> @@ -244,7 +246,7 @@ you're redefining the world and willing to take the consequences. A number of modules are included the the Perl distribution. These are described below, and all end in F<.pm>. You may also discover files in the library directory that end in either F<.pl> or F<.ph>. These are old -libaries supplied so that old programs that use them still run. The +libraries supplied so that old programs that use them still run. The F<.pl> files will all eventually be converted into standard modules, and the F<.ph> files made by B<h2ph> will probably end up as extension modules made by B<h2xs>. (Some F<.ph> values may already be available through the @@ -255,7 +257,7 @@ conversion, but it's just a mechanical process, so is far from bullet proof. They work somewhat like pragmas in that they tend to affect the compilation of your program, and thus will usually only work well when used within a -C<use>, or C<no>. These are locally scoped, so if an inner BLOCK +C<use>, or C<no>. These are locally scoped, so an inner BLOCK may countermand any of these by saying no integer; @@ -291,7 +293,7 @@ Perl pragma to predeclare sub names =head2 Standard Modules -The following modules are all expacted to behave in a well-defined +The following modules are all expected to behave in a well-defined manner with respect to namespace pollution because they use the Exporter module. See their own documentation for details. @@ -316,7 +318,7 @@ split a package for autoloading =item C<Basename> -parse file anme and path from a specification +parse file name and path from a specification =item C<Benchmark> @@ -411,11 +413,11 @@ dynamically loaded into Perl if and when you need them. Supported extension modules include the Socket, Fcntl, and POSIX modules. The following are popular C extension modules, which while available at -Perl 5.0 release time, do not come not bundled (at least, not completely) +Perl 5.0 release time, do not come bundled (at least, not completely) due to their size, volatility, or simply lack of time for adequate testing and configuration across the multitude of platforms on which Perl was beta-tested. You are encouraged to look for them in archie(1L), the Perl -FAQ or Meta-FAQ, the WWW page, and even their authors before randomly +FAQ or Meta-FAQ, the WWW page, and even with their authors before randomly posting asking for their present condition and disposition. There's no guarantee that the names or addresses below have not changed since printing, and in fact, they probably have! @@ -454,7 +456,7 @@ where. =item C<Sx> This extension module is a front to the Athena and Xlib libraries for Perl -GUI progamming, originally written by by Dominic Giampaolo +GUI programming, originally written by by Dominic Giampaolo <F<dbg@sgi.com>>, then and rewritten for Sx by FrE<eacute>dE<eacute>ric Chauveau <F<fmc@pasteur.fr>>. It's available for FTP from |