libs/DesignPattern/Bridge.pm

## --------------------------------------------------------------------------------
##  $Id: Bridge.pm,v 1.8 2003/02/14 14:20:05 joko Exp $
## --------------------------------------------------------------------------------
##  $Log: Bridge.pm,v $
##  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 );

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