307 lines
10 KiB
Perl
307 lines
10 KiB
Perl
# ==================================================================
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# Gossamer Threads Module Library - http://gossamer-threads.com/
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#
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# GT::AutoLoader
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# Author: Jason Rhinelander
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# $Id: AutoLoader.pm,v 1.13 2005/03/21 06:57:58 jagerman Exp $
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#
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# Copyright (c) 2004 Gossamer Threads Inc. All Rights Reserved.
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# ==================================================================
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package GT::AutoLoader;
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use vars qw($AUTOLOAD %LOG %PACKAGES);
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use strict qw/vars subs/; # no strict 'refs' - we need several soft references here.
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sub import {
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shift; # Discard the package, as 'use GT::AutoLoader' calls GT::AutoLoader->import(ARGS)
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my %opts = @_;
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my $pkg = caller;
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++$PACKAGES{$pkg};
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if ($opts{LOG} and ref $opts{LOG} eq 'CODE') {
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$LOG{$pkg} = delete $opts{LOG}; # Everything that requests a log will get one for all modules
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}
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delete $opts{NAME} if $opts{NAME} and $opts{NAME} eq 'AUTOLOAD'; # Allows "if ($opts{NAME})" later on.
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my $COMPILE;
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*{$pkg . ($opts{NAME} ? "::$opts{NAME}" : '::AUTOLOAD')} = sub {
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if ($opts{NAME} or !$AUTOLOAD) { # If they're using another name, it most likely means they are wrapping the AUTOLOAD, which means we have to check for $AUTOLOAD in their package.
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$AUTOLOAD = ${$pkg . '::AUTOLOAD'};
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}
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my ($func) = $AUTOLOAD =~ /([^:]+)$/; # How odd - we use $GT::AutoLoader::AUTOLOAD, even though this is run in some other package
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if ($COMPILE = \%{$pkg . '::COMPILE'}) {
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if (defined $COMPILE->{$func}) {
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for (keys %LOG) { $LOG{$_}->($pkg, $func, 'COMPILE') }
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_compile($COMPILE, $pkg, $func);
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$AUTOLOAD = '';
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goto &{"$pkg\::$func"};
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}
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}
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if ($opts{NEXT}) {
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my ($pack, $func) = $opts{NEXT} =~ /(?:(.+)::)?([^:]+?)$/;
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$pack ||= $pkg;
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${$pack . '::AUTOLOAD'} = $AUTOLOAD;
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my $next = "$pack\::$func";
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$AUTOLOAD = '';
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goto &$next;
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}
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# It doesn't exist in %COMPILE, which means we have to look through @ISA for another AUTOLOAD to pass this to
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if (my @inh = @{"$pkg\::ISA"}) {
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while (my $inh = shift @inh) {
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my $al = $inh . '::AUTOLOAD';
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if (defined &$al) {
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$$al = "$pkg\::$func"; # Sets $Other::Package::AUTOLOAD
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$AUTOLOAD = '';
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goto &$al;
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}
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elsif (my @isa = @{$inh . '::ISA'}) {
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unshift @inh, @isa;
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}
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}
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}
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my ($file, $line) = (caller)[1,2];
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$AUTOLOAD = '';
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die "$pkg ($$, GT::AutoLoader): Unknown method '$func' called at $file line $line.\n";
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};
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my $compile = "$pkg\::COMPILE";
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*$compile = \%$compile; # Implements "use vars qw/%COMPILE/" for you
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1;
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}
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BEGIN {
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if ($^C) {
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eval <<'CHECK';
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sub CHECK {
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# ------------------------------------------------------------------------------
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# In Perl 5.6+ this allows you to do: perl -cMMy::Module -e0 to make sure all
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# your %COMPILE subs compile. In versions of Perl prior to 5.6, this is simply
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# treated as a sub named "CHECK", which is never called. $^C is also 5.6+
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# specific - whether or not you are running under "-c"
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compile_all();
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}
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CHECK
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}
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}
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sub compile_all {
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my @pkg = @_;
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if (@pkg) {
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@pkg = grep +($PACKAGES{$_} or (warn "$_ is not loaded, does not use GT::AutoLoader, or is not a valid package" and 0)), @pkg;
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@pkg or die "No valid packages passed to compile_all()!";
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}
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else {
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@pkg = keys %PACKAGES;
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}
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for my $pkg (@pkg) {
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my $COMPILE = \%{$pkg . '::COMPILE'} or next;
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for my $func (keys %$COMPILE) {
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_compile($COMPILE, $pkg, $func) if $COMPILE->{$func};
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}
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}
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return 1;
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}
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sub _compile {
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# ------------------------------------------------------------------------------
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# Compiles a subroutine from a module's %COMPILE into the module's package.
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# die()s if the subroutine cannot compile or still does not exist after
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# compiling. Takes three arguments: A reference to the packages %COMPILE hash,
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# the package, and the name of the function to load.
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#
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my ($COMPILE, $pkg, $func) = @_;
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my $linenum = ($COMPILE->{$func} =~ s/^(\d+)//) ? $1+1 : 0;
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eval "package $pkg;\n#line $linenum$pkg\::$func\n$COMPILE->{$func}";
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if ($@) { die "Unable to load $pkg\::$func: $@" }
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if (not defined &{"$pkg\::$func"}) {
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die "Unable to load $pkg\::$func: Subroutine did not compile correctly (possible bad name).";
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}
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undef $COMPILE->{$func}; # Leave the key in the compile hash so that things can test to see if it was defined in the compile hash
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return;
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}
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1;
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__END__
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=head1 NAME
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GT::AutoLoader - load subroutines on demand
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=head1 SYNOPSIS
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package GT::Module;
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use GT::AutoLoader; # You now have an AUTOLOAD subroutine that will check for entries in %COMPILE
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or
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package GT::OtherModule;
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use GT::AutoLoader(NAME => '_AUTOLOAD'); # Import AUTOLOAD as _AUTOLOAD, define our own AUTOLOAD
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sub AUTOLOAD {
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...
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goto &_AUTOLOAD;
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}
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then:
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$COMPILE{sub} = __LINE__ . <<'END_OF_SUB';
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sub method_name {
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...
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}
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END_OF_SUB
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=head1 DESCRIPTION
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The B<GT::AutoLoader> module works as a way to speed up your code. Currently,
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the only thing it does is scan for a %COMPILE hash in your package. If it finds
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it, it looks for the subroutine you called, and if found compiles and runs it.
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If unable to find a subroutine to compile in %COMPILE, B<GT::AutoLoader> will
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scan your inheritance tree (@ISA) for another AUTOLOAD subroutine to pass this
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off to. If there isn't any, a fatal error occurs.
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To use B<GT::AutoLoader>, in its standard behaviour, simply put:
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C<use GT::AutoLoader;> in your module. When you use GT::AutoLoader, two things
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will happen. First, an C<AUTOLOAD> subroutine will be imported into your
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namespace that will automatically compile your subroutines only when they are
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needed, thus speeding up compile time. Secondly, a %COMPILE hash will be defined
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in your package, eliminating the need for you to: use vars qw/%COMPILE/;
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=head1 USE
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You can pass options to GT::AutoLoader to change the behaviour of the module.
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Currently, logging is the only option, however more options (perhaps including
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a different compiling scheme) will be added at some future point.
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Options are specified as import() arguments. For example:
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use GT::AutoLoader(OPTION => "value");
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=over 4
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=item NAME
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If you want to import the autoload subroutine as something other than
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'Package::AUTOLOAD', the 'NAME' option should be used. Its value is the name
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to import as. For example, to import a GT::AutoLoader AUTOLOAD named _AUTOLOAD
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(this is useful when declaring your own AUTOLOAD behaviour, but still using
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GT::AutoLoader's behaviour as a fallback), you would do something like:
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use GT::AutoLoader(NAME => '_AUTOLOAD');
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=item LOG
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Takes a code reference as its value. The code reference will be called three
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arguments - the package name, the name of the function, and the autoload method
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(Currently only 'COMPILE'). Note that this will be called for ALL autoloaded
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subroutines, not just the ones in your package.
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WARNING - you cannot put code in your log that relies on autoloaded methods -
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you'll end up throwing the program into an infinite loop.
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For example, to get a line of debugging after each subroutine is compiled, you
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could C<use GT::AutoLoader> like this:
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use GT::AutoLoader(LOG => sub {
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print "Compiled $_[1] in package $_[0]\n"
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});
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=item NEXT
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Normally, GT::AutoLoader will look for another AUTOLOAD to call in your
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package's @ISA inheritance tree. You can alter this behaviour and tell
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GT::AutoLoader what to call next using the NEXT option.
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For example, if you have a sub _AUTOLOAD { } that you wanted to call if the
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method isn't found by GT::AutoLoader, you would use GT::AutoLoader like this:
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use GT::AutoLoader(NEXT => 'Package::Name::_AUTOLOAD');
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The _AUTOLOAD function in your package will now be called if GT::AutoLoader
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can't load the method on its own. $AUTOLOAD will be set for you in whichever
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package the function you provide is in. Note that if you simply want to use an
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inherited AUTOLOAD, you B<should not> use this option; GT::AutoLoader will
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handle that just fine on its own.
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You may omit the package (Package::Name::) if the function is in your current
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package.
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=back
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=head1 compile_all
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A function exists in GT::AutoLoader to compile all %COMPILE-subroutines. By
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default (without arguments) compile_all() compiles every %COMPILE-subroutine in
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every package that has used GT::AutoLoader. You can, however, pass in a list of
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packages which compile_all() will check instead of compiling everything. Note
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that GT::AutoLoader will only compile %COMPILE-subroutines in packages that
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have used GT::AutoLoader, so if you specify package "Foo", but "Foo" hasn't
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used GT::AutoLoader, it will be ignored.
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You can do something like:
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GT::AutoLoader::compile_all(__PACKAGE__) if MOD_PERL;
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to have a GT::AutoLoader compile every %COMPILE-subroutine in the current
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package automatically under mod_perl, or you could add this code to your
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mod_perl startup file or test script:
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GT::AutoLoader::compile_all;
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Test scripts should definately use compile_all() to ensure that all subroutines
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compile correctly!
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=head1 REQUIREMENTS
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None.
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=head1 CAVEATS
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Due to the nature of Perl's AUTOLOAD handling, you must take care when using
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GT::AutoLoader in a subclass. In short, subclassed methods B<MUST NOT> be put
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into the %COMPILE hash.
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The problem is that since the subroutine does not exist in the package, Perl,
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while decending the inheritance tree, will not see it but will probably see the
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parent's method (unless nothing else has called the method, but you should
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never count on that), and call it rather than looking for your package's
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AUTOLOAD.
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This isn't to say that subclasses cannot use AUTOLOAD - just that subclasses
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cannot use autoloaded methods (%COMPILE-subroutines) if a method of the same
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name exists in the parent class. Autoloaded function calls are not affected.
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=head1 MAINTAINER
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Jason Rhinelander
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=head1 SEE ALSO
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L<GT::Base>
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=head1 COPYRIGHT
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Copyright (c) 2004 Gossamer Threads Inc. All Rights Reserved.
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http://www.gossamer-threads.com/
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=head1 VERSION
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Revision: $Id: AutoLoader.pm,v 1.13 2005/03/21 06:57:58 jagerman Exp $
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=cut
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