libs/DesignPattern/Bridge.pm

## --------------------------------------------------------------------------------
##  $Id: Bridge.pm,v 1.5 2003/01/31 01:19:50 root Exp $
## --------------------------------------------------------------------------------
##  $Log: Bridge.pm,v $
##  Revision 1.5  2003/01/31 01:19:50  root
##  + fixed: doesn't need Log::Dispatch any more, but uses it if available
##
##  Revision 1.4  2003/01/20 16:55:15  joko
##  + sub mixinPackage
##  + sub include
##
##  Revision 1.3  2002/12/16 19:57:12  joko
##  + sub unload
##
##  Revision 1.2  2002/12/15 02:06:15  joko
##  + feature to be able to specify module in non-perl-style when loading plugins: e.g. $process->load('Setup/Storage')
##
##  Revision 1.1  2002/12/13 21:46:29  joko
##  + initial check-in
##
## --------------------------------------------------------------------------------


package DesignPattern::Bridge;

use strict;
use warnings;

use base qw( DesignPattern::Object );

use Data::Dumper;

## ========   object inheritance   ========

# TODO:
#   - this is no inheritance and it doesn't have to be
#   - implement this module as a bridge to its sub-modules
#   - use the BridgePattern (http://c2.com/cgi/wiki?BridgePattern) 
#       Using patterns was already successfully done with Data::Storage::Handler
#       by implementing the AdapterPattern (http://c2.com/cgi/wiki?AdapterPattern)
#       with Perl's AUTOLOAD-mechanism
#   - try to use Perl's "tie" command to implement this functionality here instead of using AUTOLOAD!
#   - sub getChildNodes
#   - sub run

# get logger instance
my $logger = eval { Log::Dispatch::Config->instance; };
  
my $meta;

## ========   object constructor   ========
  sub new {
    my $invocant = shift;
    my $class = ref($invocant) || $invocant;
    my @args = ();
    @_ && (@args = @_);
    $logger->debug( __PACKAGE__ . "->new(@args)" ) if $logger;
    my $self = { @_ };
    #print "class: $class", "\n";
    bless $self, $class;
    ##if (my $bizWorks = shift) {
      ##$self->boot($bizWorks);
    ##}
    
    return $self;
  }


## ========   method overrider   ========
  sub AUTOLOAD2 {
    
    my $self = shift;
    our $AUTOLOAD;
    
    ##print "AUTOLOAD\n";

    my $method = $AUTOLOAD;
    $method =~ s/^.*:://;
  
    $logger->debug( __PACKAGE__ . "->" . $method . "(@_)" . " (AUTOLOAD called, not dispatched)" ) if $logger;

    ## ->DESTROY would - if not declared - trigger an AUTOLOAD also
    return if $method =~ m/::DESTROY$/;
  
##    if ($self->_filter_AUTOLOAD($method)) {
##      $self->_accessStorage();
##      $self->{STORAGEHANDLE}->$method(@_);
##    }
    
  }

  sub _getPluginPackage {
    my $self = shift;
    my $modulename_load = shift;

    # substitute slashes through double double-colons to load modules perl-style
    $modulename_load =~ s/\//::/g;
    
    # build full package name
    my $self_classname = ref $self;
    my $package = $self_classname . '::' . $modulename_load;
    return $package;
  }
  
  sub load {

    my $self = shift;
    my $modulename_load = shift;

    my $options = shift;

    my $self_modulename = ref $self;
    my $package = $self->_getPluginPackage($modulename_load);
    
    if ($meta->{loaded}->{$package}) {
      return 1;
    }
    
    #$logger->info( __PACKAGE__ . "->load: $package" ) if $logger;
    #$logger->info( __PACKAGE__ . "->load: $self_modulename" ) if $logger;
    $logger->debug( $self_modulename . "->load: $package\t[via " . __PACKAGE__ . "]" ) if $logger;

    # this is the module testing phase - use mixin doesn't seem to propagate errors by default
    eval("use $package;");
    if ($@) {
      $meta->{loaded}->{$package} = 0;
      # include caller information
      my @caller = caller;
      my $caller_msg = $caller[1] . ':' . $caller[2];
      my $msg =  __PACKAGE__ . "->load: $@ ($caller_msg)";
      if ($logger) {
        $logger->error($msg);
      } else {
        print $msg, "\n";
      }
    }

#print "ref-1: ", ref $self, "\n";
#print "ref-2: ", ref $self::SUPER, "\n";
    
    # V1:
    #bless $self, $package;

    # V2:
    # switch into foreign package and mixin plugin-module
    $self->mixinPackage($package);

    if (my $method = $options->{method}) {
      $self->$method();
    }

    return 1;
    
  }

  # TODO: maybe refactor to DesignPattern::Object? what about the '$logger'?
  sub mixinPackage {
    my $self = shift;
    my $package = shift;
    # switch into foreign package and mixin plugin-module
    my $self_classname = ref $self;
    eval("package $self_classname; use mixin '$package';");
    #eval("use mixin_all '$package';");
    if ($@) {
      $meta->{loaded}->{$package} = 0;
      $logger->error( __PACKAGE__ . "->load: $@" ) if $logger;
    } else {
      $meta->{loaded}->{$package} = 1;
    }
  }

  sub unload {

    my $self = shift;
    my $modulename_unload = shift;

    my $package = $self->_getPluginPackage($modulename_unload);
    
    if ($meta->{loaded}->{$package}) {
      $meta->{loaded}->{$package} = 0;
      my $where = __PACKAGE__ . ':' . __LINE__;
      $logger->debug( __PACKAGE__ . "->unload: FIXME: DESTROY object is not implemented at '$where'." ) if $logger;
    }

  }


  sub boot {
    my $self = shift;
    $self->_abstract_function('boot');
  }
  
  sub include {
    my $self = shift;
    my $includefile = shift;
    my $package = shift;
    # TODO: do better error-detection here / prevent dies under all circumstances!
    require $includefile;
    $self->mixinPackage($package) if $package;
  }

1;
1	joko	1.1	## --------------------------------------------------------------------------------
2	joko	1.6	## $Id: Bridge.pm,v 1.5 2003/01/31 01:19:50 root Exp $
3	joko	1.1	## --------------------------------------------------------------------------------
4	joko	1.2	## $Log: Bridge.pm,v $
5	joko	1.6	## Revision 1.5 2003/01/31 01:19:50 root
6			## + fixed: doesn't need Log::Dispatch any more, but uses it if available
7			##
8	root	1.5	## Revision 1.4 2003/01/20 16:55:15 joko
9			## + sub mixinPackage
10			## + sub include
11			##
12	joko	1.4	## Revision 1.3 2002/12/16 19:57:12 joko
13			## + sub unload
14			##
15	joko	1.3	## Revision 1.2 2002/12/15 02:06:15 joko
16			## + feature to be able to specify module in non-perl-style when loading plugins: e.g. $process->load('Setup/Storage')
17			##
18	joko	1.2	## Revision 1.1 2002/12/13 21:46:29 joko
19			## + initial check-in
20			##
21	joko	1.1	## --------------------------------------------------------------------------------
22
23
24			package DesignPattern::Bridge;
25
26			use strict;
27			use warnings;
28
29			use base qw( DesignPattern::Object );
30
31	joko	1.2	use Data::Dumper;
32
33	joko	1.1	## ======== object inheritance ========
34
35			# TODO:
36			# - this is no inheritance and it doesn't have to be
37			# - implement this module as a bridge to its sub-modules
38			# - use the BridgePattern (http://c2.com/cgi/wiki?BridgePattern)
39			# Using patterns was already successfully done with Data::Storage::Handler
40			# by implementing the AdapterPattern (http://c2.com/cgi/wiki?AdapterPattern)
41			# with Perl's AUTOLOAD-mechanism
42			# - try to use Perl's "tie" command to implement this functionality here instead of using AUTOLOAD!
43			# - sub getChildNodes
44			# - sub run
45
46			# get logger instance
47	root	1.5	my $logger = eval { Log::Dispatch::Config->instance; };
48	joko	1.1
49	joko	1.3	my $meta;
50	joko	1.1
51			## ======== object constructor ========
52			sub new {
53			my $invocant = shift;
54			my $class = ref($invocant) \|\| $invocant;
55			my @args = ();
56			@_ && (@args = @_);
57	root	1.5	$logger->debug( __PACKAGE__ . "->new(@args)" ) if $logger;
58	joko	1.1	my $self = { @_ };
59			#print "class: $class", "\n";
60			bless $self, $class;
61			##if (my $bizWorks = shift) {
62			##$self->boot($bizWorks);
63			##}
64
65			return $self;
66			}
67
68
69			## ======== method overrider ========
70			sub AUTOLOAD2 {
71
72			my $self = shift;
73			our $AUTOLOAD;
74
75			##print "AUTOLOAD\n";
76
77			my $method = $AUTOLOAD;
78			$method =~ s/^.*:://;
79
80	root	1.5	$logger->debug( __PACKAGE__ . "->" . $method . "(@_)" . " (AUTOLOAD called, not dispatched)" ) if $logger;
81	joko	1.1
82			## ->DESTROY would - if not declared - trigger an AUTOLOAD also
83			return if $method =~ m/::DESTROY$/;
84
85			## if ($self->_filter_AUTOLOAD($method)) {
86			## $self->_accessStorage();
87			## $self->{STORAGEHANDLE}->$method(@_);
88			## }
89
90			}
91	joko	1.3
92			sub _getPluginPackage {
93			my $self = shift;
94			my $modulename_load = shift;
95
96			# substitute slashes through double double-colons to load modules perl-style
97			$modulename_load =~ s/\//::/g;
98
99			# build full package name
100			my $self_classname = ref $self;
101			my $package = $self_classname . '::' . $modulename_load;
102			return $package;
103			}
104	joko	1.1
105			sub load {
106
107			my $self = shift;
108	joko	1.3	my $modulename_load = shift;
109	joko	1.1
110	joko	1.6	my $options = shift;
111
112	joko	1.4	my $self_modulename = ref $self;
113	joko	1.3	my $package = $self->_getPluginPackage($modulename_load);
114	joko	1.1
115	joko	1.3	if ($meta->{loaded}->{$package}) {
116			return 1;
117			}
118	joko	1.2
119	root	1.5	#$logger->info( __PACKAGE__ . "->load: $package" ) if $logger;
120			#$logger->info( __PACKAGE__ . "->load: $self_modulename" ) if $logger;
121			$logger->debug( $self_modulename . "->load: $package\t[via " . __PACKAGE__ . "]" ) if $logger;
122	joko	1.1
123			# this is the module testing phase - use mixin doesn't seem to propagate errors by default
124			eval("use $package;");
125			if ($@) {
126	joko	1.3	$meta->{loaded}->{$package} = 0;
127	joko	1.2	# include caller information
128			my @caller = caller;
129			my $caller_msg = $caller[1] . ':' . $caller[2];
130	root	1.5	my $msg = __PACKAGE__ . "->load: $@ ($caller_msg)";
131			if ($logger) {
132			$logger->error($msg);
133			} else {
134			print $msg, "\n";
135			}
136	joko	1.1	}
137
138			#print "ref-1: ", ref $self, "\n";
139			#print "ref-2: ", ref $self::SUPER, "\n";
140
141			# V1:
142			#bless $self, $package;
143
144			# V2:
145			# switch into foreign package and mixin plugin-module
146	joko	1.4	$self->mixinPackage($package);
147	joko	1.6
148			if (my $method = $options->{method}) {
149			$self->$method();
150			}
151	joko	1.4
152			return 1;
153
154			}
155
156			# TODO: maybe refactor to DesignPattern::Object? what about the '$logger'?
157			sub mixinPackage {
158			my $self = shift;
159			my $package = shift;
160			# switch into foreign package and mixin plugin-module
161	joko	1.3	my $self_classname = ref $self;
162	joko	1.1	eval("package $self_classname; use mixin '$package';");
163			#eval("use mixin_all '$package';");
164			if ($@) {
165	joko	1.3	$meta->{loaded}->{$package} = 0;
166	root	1.5	$logger->error( __PACKAGE__ . "->load: $@" ) if $logger;
167	joko	1.3	} else {
168			$meta->{loaded}->{$package} = 1;
169	joko	1.1	}
170	joko	1.3	}
171
172			sub unload {
173
174			my $self = shift;
175			my $modulename_unload = shift;
176
177			my $package = $self->_getPluginPackage($modulename_unload);
178	joko	1.1
179	joko	1.3	if ($meta->{loaded}->{$package}) {
180			$meta->{loaded}->{$package} = 0;
181			my $where = __PACKAGE__ . ':' . __LINE__;
182	root	1.5	$logger->debug( __PACKAGE__ . "->unload: FIXME: DESTROY object is not implemented at '$where'." ) if $logger;
183	joko	1.3	}
184
185	joko	1.1	}
186	joko	1.3
187	joko	1.1
188			sub boot {
189			my $self = shift;
190			$self->_abstract_function('boot');
191	joko	1.4	}
192
193			sub include {
194			my $self = shift;
195			my $includefile = shift;
196			my $package = shift;
197			# TODO: do better error-detection here / prevent dies under all circumstances!
198			require $includefile;
199			$self->mixinPackage($package) if $package;
200	joko	1.1	}
201
202			1;
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