libs/DesignPattern/Object.pm

## ---------------------------------------------------------------------------
##  $Id: Object.pm,v 1.6 2003/02/11 11:04:27 joko Exp $
## ---------------------------------------------------------------------------
##  $Log: Object.pm,v $
##  Revision 1.6  2003/02/11 11:04:27  joko
##  + metadata (args, caller, etc.) are now stored inside {__bridge}
##
##  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;


my $_dp_globals;

$_dp_globals = {
  TRACE => 0,
};


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;
  
  #$self->log_basic( "$classname->new( ... )" . "\t[via " . __PACKAGE__ . "]" , 'debug');
  
  # 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???
  #$self->log_basic( __PACKAGE__ . "->new( @args )", 'debug' );      # 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:
  $self->log_basic( __PACKAGE__ . ": function '$function_name' is an abstract method, please implement it in '$self_classname'.", 'warning');
  # is:
  #die( __PACKAGE__ . ": Function '$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);

  $self->log_basic( __PACKAGE__ . "->fromPackage( pkgname $pkgname args @args )", 'debug');
  
  # 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' ('$1' not found).";
      } else {
        $errmsg_critical = $errmsg_native;
      }
      # write error to logging-output (console|file|database)
      $self->log_basic( $errmsg_native, 'debug' );
      $self->log_basic( $errmsg_critical, 'warning' );
      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;
}

sub log_basic {
  my $self = shift;
  my $message = shift;
  my $level = shift;

  if ($_dp_globals->{TRACE} || ($level && $level =~ /warning|error|critical/)) {
    print $level, ": ", $message, "\n";
  }

  # get logger instance
  if (!$_dp_globals->{logger}) {
    $_dp_globals->{logger} = eval { Log::Dispatch::Config->instance; };
  }
  
  if ($_dp_globals->{logger}) {
    $_dp_globals->{logger}->log($level, $message);
  #} else {
    #print $level, ": ", $message, "\n";
  }
  
}

1;
__END__
1	joko	1.3	## ---------------------------------------------------------------------------
2	joko	1.7	## $Id: Object.pm,v 1.6 2003/02/11 11:04:27 joko Exp $
3	joko	1.3	## ---------------------------------------------------------------------------
4	joko	1.2	## $Log: Object.pm,v $
5	joko	1.7	## Revision 1.6 2003/02/11 11:04:27 joko
6			## + metadata (args, caller, etc.) are now stored inside {__bridge}
7			##
8	joko	1.6	## Revision 1.5 2003/02/09 16:24:46 joko
9			## + pseudo constructor mechanism by calling method 'constructor' on object instantiation
10			##
11	joko	1.5	## Revision 1.4 2003/01/22 17:56:49 root
12			## + fix: just use the logger if it's available
13			##
14	root	1.4	## Revision 1.3 2003/01/20 16:54:22 joko
15			## + sub fromPackage: refactored from libp's 'getNewPerlObjFromPkgName' or s.th.l.th.
16			##
17	joko	1.3	## Revision 1.2 2002/12/27 16:05:42 joko
18			## + played with Devel::CallerItem and Devel::StackTrace
19			##
20	joko	1.2	## Revision 1.1 2002/12/13 21:46:29 joko
21			## + initial check-in
22			##
23	joko	1.3	## ---------------------------------------------------------------------------
24	joko	1.1
25
26			package DesignPattern::Object;
27
28			use strict;
29			use warnings;
30	joko	1.2
31
32			use Data::Dumper;
33			#use Devel::CallerItem;
34			#use Devel::StackTrace;
35
36	joko	1.3
37	joko	1.7	my $_dp_globals;
38
39			$_dp_globals = {
40			TRACE => 0,
41			};
42
43	joko	1.3
44	joko	1.2	sub new {
45
46			# the classname in most cases
47			my $classname = shift;
48
49			# use already blessed reference, if passed in - else use the very classname
50			my $class = ref ($classname) \|\| $classname;
51
52	joko	1.7	#$self->log_basic( "$classname->new( ... )" . "\t[via " . __PACKAGE__ . "]" , 'debug');
53	joko	1.3
54	joko	1.2	# the base for our object - a plain perl hash, which ....
55			my $self = {};
56			# note:
57			# this makes an instance of an arbitrary perl variable,
58			# the most often used for this purpose is - guess it - the hash,
59			# since it resembles object-properties in a convenient way:
60			# $object->{property} = 'Hello World!';
61			# if you _do_ care about privacy you might take a look
62			# at CPAN's Tie::SecureHash or Class::Contract ... have fun!
63
64			# TODO: what about logging in here? inherit from
65			# DesignPattern::Object::Logger for this purpose....
66			# ... or would this give us (harmful) circular module dependencies???
67	joko	1.7	#$self->log_basic( __PACKAGE__ . "->new( @args )", 'debug' ); # this is not "common"!
68	joko	1.2
69
70			# remember the stacktrace: abstract this out (DesignPattern::Object::Trace) or parametrize!
71			#my $trace = Devel::StackTrace->new();
72			#print Dumper($trace);
73			#print Dumper($trace->frame(1)->args());
74
75			#print "args: ", $self->{'__caller'}->hasargs(), "\n";
76
77			#print Dumper($self);
78			#exit;
79
80	joko	1.3
81	joko	1.2	# argument-handling ...
82
83			# ... get them ...
84			my @args = ();
85			@_ && (@args = @_);
86
87			# ... check if we can coerce them into an array (this needs an even number of arguments)
88			my $argcount = $#args + 1;
89			my $fract = $argcount / 2;
90
91			my $seperate = pop @args if $fract != int($fract);
92
93			# mixin arguments
94			$self = { @args };
95
96	joko	1.6	# scan for arguments prefixed by a double underscore '__'
97			foreach (keys %$self) {
98			if (/^__(.+?)$/) {
99			$self->{__bridge}->{$1} = $self->{$_};
100			delete $self->{$_};
101			}
102			}
103
104			# mixin seperate - FIXME: should this not be done after blessing?
105			$self->{__bridge}->{'arg'} = $seperate if $seperate;
106	joko	1.2
107			# ... bless hash into object using classname
108			bless $self, $class;
109	joko	1.3
110			# remember the caller
111	joko	1.6	$self->{__bridge}->{caller_module} = caller;
112	joko	1.3	#print Dumper(caller(2));
113			#exit;
114
115	joko	1.6	$self->{__bridge}->{class_name} = $classname;
116
117			# patches for backward compatibility
118			$self->{'__arg'} = $self->{__bridge}->{'arg'} if $self->{__bridge}->{'arg'};
119			$self->{'__caller'} = $self->{__bridge}->{caller_module} if $self->{__bridge}->{caller_module};
120			$self->{'__classname'} = $self->{__bridge}->{class_name} if $self->{__bridge}->{class_name};
121	joko	1.3
122	joko	1.2	$self->_init() if $self->can('_init');
123	joko	1.5	$self->constructor() if $self->can('constructor');
124	joko	1.6
125			# trace
126			#print Dumper($self);
127			#exit;
128	joko	1.3
129	joko	1.2	return $self;
130			}
131	joko	1.1
132			sub _abstract_function {
133			my $self = shift;
134			my $self_classname = ref $self;
135			my $function_name = shift;
136			# was:
137	joko	1.7	$self->log_basic( __PACKAGE__ . ": function '$function_name' is an abstract method, please implement it in '$self_classname'.", 'warning');
138	joko	1.1	# is:
139	joko	1.3	#die( __PACKAGE__ . ": Function '$function_name' is an abstract method, please implement it in '$self_classname'.");
140	joko	1.1	#exit;
141	joko	1.3	}
142
143			sub fromPackage {
144			my $self = shift;
145			#my $self_classname = ref $self;
146			my $pkgname = shift;
147			my @args = @_;
148			# my $args = shift;
149
150			# my $caller = $self->{'__caller'};
151
152			#print Dumper($args);
153
154	joko	1.7	$self->log_basic( __PACKAGE__ . "->fromPackage( pkgname $pkgname args @args )", 'debug');
155	joko	1.3
156			# perl-load
157			my $evstring = "use $pkgname;";
158			eval($evstring);
159
160			# report errors
161			if ($@) {
162			# build error-messages
163			my $errmsg_native = __PACKAGE__ . ':' . __LINE__ . " Error in eval \"$evstring\": " . $@;
164			#my $classname = $self->{__classname};
165			my $errmsg_critical = '';
166			if ($errmsg_native =~ m/Can't locate (.+?) in \@INC/) {
167	joko	1.7	$errmsg_critical = "Could not instantiate object from package '$pkgname' ('$1' not found).";
168	joko	1.3	} else {
169			$errmsg_critical = $errmsg_native;
170			}
171			# write error to logging-output (console\|file\|database)
172	joko	1.7	$self->log_basic( $errmsg_native, 'debug' );
173			$self->log_basic( $errmsg_critical, 'warning' );
174	joko	1.3	return;
175			}
176
177			# object-creation
178			my $object = $pkgname->new(@args);
179
180			# run boot-methods on object
181			$object->_init() if $object->can('_init');
182	joko	1.5	$object->constructor() if $object->can('constructor');
183	joko	1.3
184			return $object;
185	joko	1.1	}
186
187	joko	1.7	sub log_basic {
188			my $self = shift;
189			my $message = shift;
190			my $level = shift;
191
192			if ($_dp_globals->{TRACE} \|\| ($level && $level =~ /warning\|error\|critical/)) {
193			print $level, ": ", $message, "\n";
194			}
195
196			# get logger instance
197			if (!$_dp_globals->{logger}) {
198			$_dp_globals->{logger} = eval { Log::Dispatch::Config->instance; };
199			}
200
201			if ($_dp_globals->{logger}) {
202			$_dp_globals->{logger}->log($level, $message);
203			#} else {
204			#print $level, ": ", $message, "\n";
205			}
206
207			}
208
209	joko	1.1	1;
210	joko	1.7	__END__
MailToCvsAdmin">MailToCvsAdmin	ViewVC Help
Powered by ViewVC 1.1.26