libs/DesignPattern/Object.pm

## ---------------------------------------------------------------------------
##  $Id: Object.pm,v 1.5 2003/02/09 16:24:46 joko Exp $
## ---------------------------------------------------------------------------
##  $Log: Object.pm,v $
##  Revision 1.5  2003/02/09 16:24:46  joko
##  + pseudo constructor mechanism by calling method 'constructor' on object instantiation
##
##  Revision 1.4  2003/01/22 17:56:49  root
##  + fix: just use the logger if it's available
##
##  Revision 1.3  2003/01/20 16:54:22  joko
##  + sub fromPackage: refactored from libp's 'getNewPerlObjFromPkgName' or s.th.l.th.
##
##  Revision 1.2  2002/12/27 16:05:42  joko
##  + played with Devel::CallerItem and Devel::StackTrace
##
##  Revision 1.1  2002/12/13 21:46:29  joko
##  + initial check-in
##
## ---------------------------------------------------------------------------


package DesignPattern::Object;

use strict;
use warnings;


use Data::Dumper;
#use Devel::CallerItem;
#use Devel::StackTrace;


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

sub new {
  
  # the classname in most cases
  my $classname = shift;
  
  # use already blessed reference, if passed in - else use the very classname
  my $class = ref ($classname) || $classname;
  
  $logger->debug( "$classname->new( ... )" . "\t[via " . __PACKAGE__ . "]" ) if $logger;
  
  # the base for our object - a plain perl hash, which ....
  my $self = {};
  # note:
  # this makes an instance of an arbitrary perl variable,
  # the most often used for this purpose is - guess it - the hash, 
  # since it resembles object-properties in a convenient way:
  #   $object->{property} = 'Hello World!';
  # if you _do_ care about privacy you might take a look 
  # at CPAN's Tie::SecureHash or Class::Contract ...   have fun!
  
  # TODO: what about logging in here? inherit from 
  # DesignPattern::Object::Logger for this purpose....
  # ... or would this give us (harmful) circular module dependencies???
  #$logger->debug( __PACKAGE__ . "->new( @args )" );      # this is not "common"!

    
  # remember the stacktrace: abstract this out (DesignPattern::Object::Trace) or parametrize!
  #my $trace = Devel::StackTrace->new();
  #print Dumper($trace);
  #print Dumper($trace->frame(1)->args());

#print "args: ", $self->{'__caller'}->hasargs(), "\n";

  #print Dumper($self);
  #exit;


  # argument-handling ...

    # ... get them ...
    my @args = ();
    @_ && (@args = @_);
    
    # ... check if we can coerce them into an array (this needs an even number of arguments)
  my $argcount = $#args + 1;
  my $fract = $argcount / 2;
  
  my $seperate = pop @args if $fract != int($fract);

  # mixin arguments
  $self = { @args };
  
  # scan for arguments prefixed by a double underscore '__'
  foreach (keys %$self) {
    if (/^__(.+?)$/) {
      $self->{__bridge}->{$1} = $self->{$_};
      delete $self->{$_};
    }
  }
  
  # mixin seperate - FIXME: should this not be done after blessing?
  $self->{__bridge}->{'arg'} = $seperate if $seperate;

  # ... bless hash into object using classname
  bless $self, $class;

  # remember the caller
    $self->{__bridge}->{caller_module}  = caller;
    #print Dumper(caller(2));
    #exit;

  $self->{__bridge}->{class_name} = $classname;

  # patches for backward compatibility
    $self->{'__arg'} = $self->{__bridge}->{'arg'} if $self->{__bridge}->{'arg'};
    $self->{'__caller'} = $self->{__bridge}->{caller_module} if $self->{__bridge}->{caller_module};
    $self->{'__classname'} = $self->{__bridge}->{class_name} if $self->{__bridge}->{class_name};

  $self->_init() if $self->can('_init');
  $self->constructor() if $self->can('constructor');

  # trace
    #print Dumper($self);
    #exit;

  return $self;
}  

sub _abstract_function {
  my $self = shift;
  my $self_classname = ref $self;
  my $function_name = shift;
  # was:
  $logger->warning( __PACKAGE__ . ": function '$function_name' is an abstract method, please implement it in '$self_classname'.");
  # is:
  #die( __PACKAGE__ . ": Function '$function_name' is an abstract method, please implement it in '$self_classname'.");
  #exit;
}

sub fromPackage {
  my $self = shift;
  #my $self_classname = ref $self;
  my $pkgname = shift;
  my @args = @_;
#  my $args = shift;

#      my $caller = $self->{'__caller'};

#print Dumper($args);

  $logger->debug( __PACKAGE__ . "->fromPackage( pkgname $pkgname args @args )" );
  
  # perl-load
    my $evstring = "use $pkgname;";
    eval($evstring);
  
  # report errors
    if ($@) {
      # build error-messages
      my $errmsg_native = __PACKAGE__ . ':' . __LINE__ . " Error in eval \"$evstring\": " .  $@;
      #my $classname = $self->{__classname};
      my $errmsg_critical = '';
      if ($errmsg_native =~ m/Can't locate (.+?) in \@INC/) {
        $errmsg_critical = "Could not instantiate object from package '$pkgname' - location of '$1' failed.";
      } else {
        $errmsg_critical = $errmsg_native;
      }
      # write error to logging-output (console|file|database)
      $logger->debug( $errmsg_native );
      $logger->critical( $errmsg_critical );
      return;
    }
  
  # object-creation
    my $object = $pkgname->new(@args);

  # run boot-methods on object
    $object->_init() if $object->can('_init');
    $object->constructor() if $object->can('constructor');

  return $object;
}

1;
1	joko	1.3	## ---------------------------------------------------------------------------
2	joko	1.6	## $Id: Object.pm,v 1.5 2003/02/09 16:24:46 joko Exp $
3	joko	1.3	## ---------------------------------------------------------------------------
4	joko	1.2	## $Log: Object.pm,v $
5	joko	1.6	## Revision 1.5 2003/02/09 16:24:46 joko
6			## + pseudo constructor mechanism by calling method 'constructor' on object instantiation
7			##
8	joko	1.5	## Revision 1.4 2003/01/22 17:56:49 root
9			## + fix: just use the logger if it's available
10			##
11	root	1.4	## Revision 1.3 2003/01/20 16:54:22 joko
12			## + sub fromPackage: refactored from libp's 'getNewPerlObjFromPkgName' or s.th.l.th.
13			##
14	joko	1.3	## Revision 1.2 2002/12/27 16:05:42 joko
15			## + played with Devel::CallerItem and Devel::StackTrace
16			##
17	joko	1.2	## Revision 1.1 2002/12/13 21:46:29 joko
18			## + initial check-in
19			##
20	joko	1.3	## ---------------------------------------------------------------------------
21	joko	1.1
22
23			package DesignPattern::Object;
24
25			use strict;
26			use warnings;
27	joko	1.2
28
29			use Data::Dumper;
30			#use Devel::CallerItem;
31			#use Devel::StackTrace;
32
33	joko	1.3
34			# get logger instance
35	root	1.4	my $logger = eval { Log::Dispatch::Config->instance; };
36	joko	1.3
37	joko	1.2	sub new {
38
39			# the classname in most cases
40			my $classname = shift;
41
42			# use already blessed reference, if passed in - else use the very classname
43			my $class = ref ($classname) \|\| $classname;
44
45	root	1.4	$logger->debug( "$classname->new( ... )" . "\t[via " . __PACKAGE__ . "]" ) if $logger;
46	joko	1.3
47	joko	1.2	# the base for our object - a plain perl hash, which ....
48			my $self = {};
49			# note:
50			# this makes an instance of an arbitrary perl variable,
51			# the most often used for this purpose is - guess it - the hash,
52			# since it resembles object-properties in a convenient way:
53			# $object->{property} = 'Hello World!';
54			# if you _do_ care about privacy you might take a look
55			# at CPAN's Tie::SecureHash or Class::Contract ... have fun!
56
57			# TODO: what about logging in here? inherit from
58			# DesignPattern::Object::Logger for this purpose....
59			# ... or would this give us (harmful) circular module dependencies???
60			#$logger->debug( __PACKAGE__ . "->new( @args )" ); # this is not "common"!
61
62
63			# remember the stacktrace: abstract this out (DesignPattern::Object::Trace) or parametrize!
64			#my $trace = Devel::StackTrace->new();
65			#print Dumper($trace);
66			#print Dumper($trace->frame(1)->args());
67
68			#print "args: ", $self->{'__caller'}->hasargs(), "\n";
69
70			#print Dumper($self);
71			#exit;
72
73	joko	1.3
74	joko	1.2	# argument-handling ...
75
76			# ... get them ...
77			my @args = ();
78			@_ && (@args = @_);
79
80			# ... check if we can coerce them into an array (this needs an even number of arguments)
81			my $argcount = $#args + 1;
82			my $fract = $argcount / 2;
83
84			my $seperate = pop @args if $fract != int($fract);
85
86			# mixin arguments
87			$self = { @args };
88
89	joko	1.6	# scan for arguments prefixed by a double underscore '__'
90			foreach (keys %$self) {
91			if (/^__(.+?)$/) {
92			$self->{__bridge}->{$1} = $self->{$_};
93			delete $self->{$_};
94			}
95			}
96
97			# mixin seperate - FIXME: should this not be done after blessing?
98			$self->{__bridge}->{'arg'} = $seperate if $seperate;
99	joko	1.2
100			# ... bless hash into object using classname
101			bless $self, $class;
102	joko	1.3
103			# remember the caller
104	joko	1.6	$self->{__bridge}->{caller_module} = caller;
105	joko	1.3	#print Dumper(caller(2));
106			#exit;
107
108	joko	1.6	$self->{__bridge}->{class_name} = $classname;
109
110			# patches for backward compatibility
111			$self->{'__arg'} = $self->{__bridge}->{'arg'} if $self->{__bridge}->{'arg'};
112			$self->{'__caller'} = $self->{__bridge}->{caller_module} if $self->{__bridge}->{caller_module};
113			$self->{'__classname'} = $self->{__bridge}->{class_name} if $self->{__bridge}->{class_name};
114	joko	1.3
115	joko	1.2	$self->_init() if $self->can('_init');
116	joko	1.5	$self->constructor() if $self->can('constructor');
117	joko	1.6
118			# trace
119			#print Dumper($self);
120			#exit;
121	joko	1.3
122	joko	1.2	return $self;
123			}
124	joko	1.1
125			sub _abstract_function {
126			my $self = shift;
127			my $self_classname = ref $self;
128			my $function_name = shift;
129			# was:
130	joko	1.3	$logger->warning( __PACKAGE__ . ": function '$function_name' is an abstract method, please implement it in '$self_classname'.");
131	joko	1.1	# is:
132	joko	1.3	#die( __PACKAGE__ . ": Function '$function_name' is an abstract method, please implement it in '$self_classname'.");
133	joko	1.1	#exit;
134	joko	1.3	}
135
136			sub fromPackage {
137			my $self = shift;
138			#my $self_classname = ref $self;
139			my $pkgname = shift;
140			my @args = @_;
141			# my $args = shift;
142
143			# my $caller = $self->{'__caller'};
144
145			#print Dumper($args);
146
147			$logger->debug( __PACKAGE__ . "->fromPackage( pkgname $pkgname args @args )" );
148
149			# perl-load
150			my $evstring = "use $pkgname;";
151			eval($evstring);
152
153			# report errors
154			if ($@) {
155			# build error-messages
156			my $errmsg_native = __PACKAGE__ . ':' . __LINE__ . " Error in eval \"$evstring\": " . $@;
157			#my $classname = $self->{__classname};
158			my $errmsg_critical = '';
159			if ($errmsg_native =~ m/Can't locate (.+?) in \@INC/) {
160			$errmsg_critical = "Could not instantiate object from package '$pkgname' - location of '$1' failed.";
161			} else {
162			$errmsg_critical = $errmsg_native;
163			}
164			# write error to logging-output (console\|file\|database)
165			$logger->debug( $errmsg_native );
166			$logger->critical( $errmsg_critical );
167			return;
168			}
169
170			# object-creation
171			my $object = $pkgname->new(@args);
172
173			# run boot-methods on object
174			$object->_init() if $object->can('_init');
175	joko	1.5	$object->constructor() if $object->can('constructor');
176	joko	1.3
177			return $object;
178	joko	1.1	}
179
180			1;
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