libs/DesignPattern/Bridge.pm

## --------------------------------------------------------------------------------
##  $Id: Bridge.pm,v 1.9 2003/02/18 18:35:30 joko Exp $
## --------------------------------------------------------------------------------
##  $Log: Bridge.pm,v $
##  Revision 1.9  2003/02/18 18:35:30  joko
##  + encapsulated/abstracted some more functionality: sub load_single
##
##  Revision 1.8  2003/02/14 14:20:05  joko
##  + modified mixin behaviour
##
##  Revision 1.7  2003/02/11 10:34:19  joko
##  + loaded module may now lack 'mixin::with' declaration
##  + this gets us the possibility to load modules from any perl namespace
##     + enabled this mechanism
##
##  Revision 1.6  2003/02/09 16:22:51  joko
##  + pseudo constructor mechanism via options
##
##  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
  DesignPattern::Exception
);

use Data::Dumper;

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

# TODO / REFACTORING PROPOSAL
# leading from Data::Storage to code abstracted out into this module - DesignPattern::Bridge
#   - 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

# 2003-02-11, joko: does this have anything in parallel with CPAN's Class::Inner?


# 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 = { @_ };

  # trace
    #print "class: $class", "\n";

  # create instance
  bless $self, $class;
  
  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;
      # name
      my $package = $modulename_load;
      
      # if package is absolute, cut away prefix ('/' or '::')
      if ($package !~ s/^:://) {
        # else: prefix with base classname if above name is relative (lacks of '/' or '::')
        $package = $self_classname . '::' . $package 
      }
    
    return $package;
  }
  
  sub load {

    my $self = shift;
    my $modulename = shift;
    my $options = shift;

    if (ref $modulename eq 'ARRAY') {
      foreach (@$modulename) {
        $self->load_single($_, $options);
      }
    } else {
      $self->load_single($modulename, $options);
    }

  }

  sub load_single {

    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;");
    $self->checkExceptions();
    
=pod    
    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";
      }
    }
=cut

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

    # V2:
    $self->mixinPackage($package);
    
    if (my $method = $options->{method}) {
      $self->$method();
    }

    return 1;
    
  }
  
  sub mixinPackage {
    my $self = shift;
    my $package = shift;
    
    # switch into foreign package and prepare for mixin
    $self->mixin_prepare($package);

    # switch into local package (scope which uses DesignPattern::Bridge) and mixin plugin-module
    $self->mixin_do($package);

  }

  # TODO: maybe refactor to DesignPattern::Object? what about the '$logger'?
  sub mixin_prepare {
    my $self = shift;
    my $package = shift;
    my $self_classname = ref $self;
    eval("package $package; use mixin::with '$self_classname';");

    # FIXME: --- this is redundant ---
    if ($@) {
      $meta->{loaded}->{$package} = 0;
      $logger->error( __PACKAGE__ . "->load: $@" ) if $logger;
    } else {
      $meta->{loaded}->{$package} = 1;
    }
    # FIXME: --- this is redundant ---

  }

  sub mixin_do {
    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';");

    # FIXME: --- this is redundant ---
    if ($@) {
      $meta->{loaded}->{$package} = 0;
      $logger->error( __PACKAGE__ . "->load: $@" ) if $logger;
    } else {
      $meta->{loaded}->{$package} = 1;
    }
    # FIXME: --- this is redundant ---

  }

  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;
__END__
1	joko	1.1	## --------------------------------------------------------------------------------
2	joko	1.10	## $Id: Bridge.pm,v 1.9 2003/02/18 18:35:30 joko Exp $
3	joko	1.1	## --------------------------------------------------------------------------------
4	joko	1.2	## $Log: Bridge.pm,v $
5	joko	1.10	## Revision 1.9 2003/02/18 18:35:30 joko
6			## + encapsulated/abstracted some more functionality: sub load_single
7			##
8	joko	1.9	## Revision 1.8 2003/02/14 14:20:05 joko
9			## + modified mixin behaviour
10			##
11	joko	1.8	## Revision 1.7 2003/02/11 10:34:19 joko
12			## + loaded module may now lack 'mixin::with' declaration
13			## + this gets us the possibility to load modules from any perl namespace
14			## + enabled this mechanism
15			##
16	joko	1.7	## Revision 1.6 2003/02/09 16:22:51 joko
17			## + pseudo constructor mechanism via options
18			##
19	joko	1.6	## Revision 1.5 2003/01/31 01:19:50 root
20			## + fixed: doesn't need Log::Dispatch any more, but uses it if available
21			##
22	root	1.5	## Revision 1.4 2003/01/20 16:55:15 joko
23			## + sub mixinPackage
24			## + sub include
25			##
26	joko	1.4	## Revision 1.3 2002/12/16 19:57:12 joko
27			## + sub unload
28			##
29	joko	1.3	## Revision 1.2 2002/12/15 02:06:15 joko
30			## + feature to be able to specify module in non-perl-style when loading plugins: e.g. $process->load('Setup/Storage')
31			##
32	joko	1.2	## Revision 1.1 2002/12/13 21:46:29 joko
33			## + initial check-in
34			##
35	joko	1.1	## --------------------------------------------------------------------------------
36
37
38			package DesignPattern::Bridge;
39
40			use strict;
41			use warnings;
42
43	joko	1.10	use base qw(
44			DesignPattern::Object
45			DesignPattern::Exception
46			);
47	joko	1.1
48	joko	1.2	use Data::Dumper;
49
50	joko	1.1	## ======== object inheritance ========
51
52	joko	1.7	# TODO / REFACTORING PROPOSAL
53			# leading from Data::Storage to code abstracted out into this module - DesignPattern::Bridge
54	joko	1.1	# - this is no inheritance and it doesn't have to be
55			# - implement this module as a bridge to its sub-modules
56			# - use the BridgePattern (http://c2.com/cgi/wiki?BridgePattern)
57			# Using patterns was already successfully done with Data::Storage::Handler
58			# by implementing the AdapterPattern (http://c2.com/cgi/wiki?AdapterPattern)
59			# with Perl's AUTOLOAD-mechanism
60			# - try to use Perl's "tie" command to implement this functionality here instead of using AUTOLOAD!
61			# - sub getChildNodes
62			# - sub run
63
64	joko	1.7	# 2003-02-11, joko: does this have anything in parallel with CPAN's Class::Inner?
65
66
67	joko	1.1	# get logger instance
68	root	1.5	my $logger = eval { Log::Dispatch::Config->instance; };
69	joko	1.1
70	joko	1.3	my $meta;
71	joko	1.1
72			## ======== object constructor ========
73	joko	1.7	sub new {
74			my $invocant = shift;
75			my $class = ref($invocant) \|\| $invocant;
76			my @args = ();
77			@_ && (@args = @_);
78			$logger->debug( __PACKAGE__ . "->new(@args)" ) if $logger;
79			my $self = { @_ };
80
81			# trace
82	joko	1.1	#print "class: $class", "\n";
83	joko	1.7
84			# create instance
85			bless $self, $class;
86
87			return $self;
88			}
89	joko	1.1
90
91			## ======== method overrider ========
92			sub AUTOLOAD2 {
93
94			my $self = shift;
95			our $AUTOLOAD;
96
97			##print "AUTOLOAD\n";
98
99			my $method = $AUTOLOAD;
100			$method =~ s/^.*:://;
101
102	root	1.5	$logger->debug( __PACKAGE__ . "->" . $method . "(@_)" . " (AUTOLOAD called, not dispatched)" ) if $logger;
103	joko	1.1
104			## ->DESTROY would - if not declared - trigger an AUTOLOAD also
105			return if $method =~ m/::DESTROY$/;
106
107			## if ($self->_filter_AUTOLOAD($method)) {
108			## $self->_accessStorage();
109			## $self->{STORAGEHANDLE}->$method(@_);
110			## }
111
112			}
113	joko	1.3
114			sub _getPluginPackage {
115			my $self = shift;
116			my $modulename_load = shift;
117
118			# substitute slashes through double double-colons to load modules perl-style
119			$modulename_load =~ s/\//::/g;
120
121			# build full package name
122			my $self_classname = ref $self;
123	joko	1.7	# name
124			my $package = $modulename_load;
125
126			# if package is absolute, cut away prefix ('/' or '::')
127			if ($package !~ s/^:://) {
128			# else: prefix with base classname if above name is relative (lacks of '/' or '::')
129			$package = $self_classname . '::' . $package
130			}
131
132	joko	1.3	return $package;
133			}
134	joko	1.1
135			sub load {
136	joko	1.9
137			my $self = shift;
138			my $modulename = shift;
139			my $options = shift;
140
141			if (ref $modulename eq 'ARRAY') {
142			foreach (@$modulename) {
143			$self->load_single($_, $options);
144			}
145			} else {
146			$self->load_single($modulename, $options);
147			}
148
149			}
150
151			sub load_single {
152	joko	1.1
153			my $self = shift;
154	joko	1.3	my $modulename_load = shift;
155	joko	1.1
156	joko	1.6	my $options = shift;
157
158	joko	1.4	my $self_modulename = ref $self;
159	joko	1.3	my $package = $self->_getPluginPackage($modulename_load);
160	joko	1.1
161	joko	1.3	if ($meta->{loaded}->{$package}) {
162			return 1;
163			}
164	joko	1.2
165	root	1.5	#$logger->info( __PACKAGE__ . "->load: $package" ) if $logger;
166			#$logger->info( __PACKAGE__ . "->load: $self_modulename" ) if $logger;
167			$logger->debug( $self_modulename . "->load: $package\t[via " . __PACKAGE__ . "]" ) if $logger;
168	joko	1.1
169			# this is the module testing phase - use mixin doesn't seem to propagate errors by default
170			eval("use $package;");
171	joko	1.10	$self->checkExceptions();
172
173			=pod
174	joko	1.1	if ($@) {
175	joko	1.3	$meta->{loaded}->{$package} = 0;
176	joko	1.2	# include caller information
177			my @caller = caller;
178			my $caller_msg = $caller[1] . ':' . $caller[2];
179	root	1.5	my $msg = __PACKAGE__ . "->load: $@ ($caller_msg)";
180			if ($logger) {
181			$logger->error($msg);
182			} else {
183			print $msg, "\n";
184			}
185	joko	1.1	}
186	joko	1.10	=cut
187	joko	1.1
188			#print "ref-1: ", ref $self, "\n";
189			#print "ref-2: ", ref $self::SUPER, "\n";
190
191			# V1:
192			#bless $self, $package;
193
194			# V2:
195	joko	1.8	$self->mixinPackage($package);
196
197			if (my $method = $options->{method}) {
198			$self->$method();
199			}
200	joko	1.7
201	joko	1.8	return 1;
202
203			}
204
205			sub mixinPackage {
206			my $self = shift;
207			my $package = shift;
208
209	joko	1.7	# switch into foreign package and prepare for mixin
210			$self->mixin_prepare($package);
211
212			# switch into local package (scope which uses DesignPattern::Bridge) and mixin plugin-module
213			$self->mixin_do($package);
214	joko	1.6
215	joko	1.4	}
216
217			# TODO: maybe refactor to DesignPattern::Object? what about the '$logger'?
218	joko	1.7	sub mixin_prepare {
219			my $self = shift;
220			my $package = shift;
221			my $self_classname = ref $self;
222			eval("package $package; use mixin::with '$self_classname';");
223
224			# FIXME: --- this is redundant ---
225			if ($@) {
226			$meta->{loaded}->{$package} = 0;
227			$logger->error( __PACKAGE__ . "->load: $@" ) if $logger;
228			} else {
229			$meta->{loaded}->{$package} = 1;
230			}
231			# FIXME: --- this is redundant ---
232
233			}
234
235			sub mixin_do {
236	joko	1.4	my $self = shift;
237			my $package = shift;
238			# switch into foreign package and mixin plugin-module
239	joko	1.3	my $self_classname = ref $self;
240	joko	1.1	eval("package $self_classname; use mixin '$package';");
241			#eval("use mixin_all '$package';");
242	joko	1.7
243			# FIXME: --- this is redundant ---
244	joko	1.1	if ($@) {
245	joko	1.3	$meta->{loaded}->{$package} = 0;
246	root	1.5	$logger->error( __PACKAGE__ . "->load: $@" ) if $logger;
247	joko	1.3	} else {
248			$meta->{loaded}->{$package} = 1;
249	joko	1.1	}
250	joko	1.7	# FIXME: --- this is redundant ---
251
252	joko	1.3	}
253
254			sub unload {
255
256			my $self = shift;
257			my $modulename_unload = shift;
258
259			my $package = $self->_getPluginPackage($modulename_unload);
260	joko	1.1
261	joko	1.3	if ($meta->{loaded}->{$package}) {
262			$meta->{loaded}->{$package} = 0;
263			my $where = __PACKAGE__ . ':' . __LINE__;
264	root	1.5	$logger->debug( __PACKAGE__ . "->unload: FIXME: DESTROY object is not implemented at '$where'." ) if $logger;
265	joko	1.3	}
266
267	joko	1.1	}
268	joko	1.3
269	joko	1.1
270			sub boot {
271			my $self = shift;
272			$self->_abstract_function('boot');
273	joko	1.4	}
274
275			sub include {
276			my $self = shift;
277			my $includefile = shift;
278			my $package = shift;
279			# TODO: do better error-detection here / prevent dies under all circumstances!
280			require $includefile;
281			$self->mixinPackage($package) if $package;
282	joko	1.1	}
283
284			1;
285	joko	1.7	__END__
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