libs/DesignPattern/Bridge.pm

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