libs/DesignPattern/Object.pm

## ---------------------------------------------------------------------------
##  $Id: Object.pm,v 1.8 2003/02/19 00:36:59 joko Exp $
## ---------------------------------------------------------------------------
##  $Log: Object.pm,v $
##  Revision 1.8  2003/02/19 00:36:59  joko
##  + bugfix: this {logger} is the instance itself, so has to be fed with ( level => xyz and namespace => xyz )
##  + minor modifications in behaviour
##
##  Revision 1.7  2003/02/18 18:34:35  joko
##  + fix: just logs if possible (sub log_basic)
##
##  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 $issuer = __PACKAGE__ . ':' . __LINE__;
      my $errmsg_native = "Error in eval: " .  $@;
      #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( $errmsg_native . " (issuer='$issuer', code='$evstring')", 'debug' );
      $self->log_basic( $errmsg_critical, 'warning' );
      return;
    }
  
  # object-creation
    my $object = $pkgname->new(@args);

  # trace
    #print Dumper($object);

  # 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;
  
  #return;
  $level ||= 'info';

  my $notSoGood = ($level =~ /warning|error|critical/);
  
  # STDERR?
  if ($level && $notSoGood) {
    print STDERR $level, ": ", $message, "\n";
  }

  # STDOUT?
  if ($_dp_globals->{TRACE} || $notSoGood) {
    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 => $level, message => $message);
  #} else {
    #print $level, ": ", $message, "\n";
  }
  
}

1;
__END__
1	joko	1.3	## ---------------------------------------------------------------------------
2	joko	1.9	## $Id: Object.pm,v 1.8 2003/02/19 00:36:59 joko Exp $
3	joko	1.3	## ---------------------------------------------------------------------------
4	joko	1.2	## $Log: Object.pm,v $
5	joko	1.9	## Revision 1.8 2003/02/19 00:36:59 joko
6			## + bugfix: this {logger} is the instance itself, so has to be fed with ( level => xyz and namespace => xyz )
7			## + minor modifications in behaviour
8			##
9	joko	1.8	## Revision 1.7 2003/02/18 18:34:35 joko
10			## + fix: just logs if possible (sub log_basic)
11			##
12	joko	1.7	## Revision 1.6 2003/02/11 11:04:27 joko
13			## + metadata (args, caller, etc.) are now stored inside {__bridge}
14			##
15	joko	1.6	## Revision 1.5 2003/02/09 16:24:46 joko
16			## + pseudo constructor mechanism by calling method 'constructor' on object instantiation
17			##
18	joko	1.5	## Revision 1.4 2003/01/22 17:56:49 root
19			## + fix: just use the logger if it's available
20			##
21	root	1.4	## Revision 1.3 2003/01/20 16:54:22 joko
22			## + sub fromPackage: refactored from libp's 'getNewPerlObjFromPkgName' or s.th.l.th.
23			##
24	joko	1.3	## Revision 1.2 2002/12/27 16:05:42 joko
25			## + played with Devel::CallerItem and Devel::StackTrace
26			##
27	joko	1.2	## Revision 1.1 2002/12/13 21:46:29 joko
28			## + initial check-in
29			##
30	joko	1.3	## ---------------------------------------------------------------------------
31	joko	1.1
32
33			package DesignPattern::Object;
34
35			use strict;
36			use warnings;
37	joko	1.2
38
39			use Data::Dumper;
40			#use Devel::CallerItem;
41			#use Devel::StackTrace;
42
43	joko	1.3
44	joko	1.7	my $_dp_globals;
45
46			$_dp_globals = {
47			TRACE => 0,
48			};
49
50	joko	1.3
51	joko	1.2	sub new {
52
53			# the classname in most cases
54			my $classname = shift;
55
56			# use already blessed reference, if passed in - else use the very classname
57			my $class = ref ($classname) \|\| $classname;
58
59	joko	1.7	#$self->log_basic( "$classname->new( ... )" . "\t[via " . __PACKAGE__ . "]" , 'debug');
60	joko	1.3
61	joko	1.2	# the base for our object - a plain perl hash, which ....
62			my $self = {};
63			# note:
64			# this makes an instance of an arbitrary perl variable,
65			# the most often used for this purpose is - guess it - the hash,
66			# since it resembles object-properties in a convenient way:
67			# $object->{property} = 'Hello World!';
68			# if you _do_ care about privacy you might take a look
69			# at CPAN's Tie::SecureHash or Class::Contract ... have fun!
70
71			# TODO: what about logging in here? inherit from
72			# DesignPattern::Object::Logger for this purpose....
73			# ... or would this give us (harmful) circular module dependencies???
74	joko	1.7	#$self->log_basic( __PACKAGE__ . "->new( @args )", 'debug' ); # this is not "common"!
75	joko	1.2
76
77			# remember the stacktrace: abstract this out (DesignPattern::Object::Trace) or parametrize!
78			#my $trace = Devel::StackTrace->new();
79			#print Dumper($trace);
80			#print Dumper($trace->frame(1)->args());
81
82			#print "args: ", $self->{'__caller'}->hasargs(), "\n";
83
84			#print Dumper($self);
85			#exit;
86
87	joko	1.3
88	joko	1.2	# argument-handling ...
89
90			# ... get them ...
91			my @args = ();
92			@_ && (@args = @_);
93
94			# ... check if we can coerce them into an array (this needs an even number of arguments)
95			my $argcount = $#args + 1;
96			my $fract = $argcount / 2;
97
98			my $seperate = pop @args if $fract != int($fract);
99
100			# mixin arguments
101			$self = { @args };
102
103	joko	1.6	# scan for arguments prefixed by a double underscore '__'
104			foreach (keys %$self) {
105			if (/^__(.+?)$/) {
106			$self->{__bridge}->{$1} = $self->{$_};
107			delete $self->{$_};
108			}
109			}
110
111			# mixin seperate - FIXME: should this not be done after blessing?
112			$self->{__bridge}->{'arg'} = $seperate if $seperate;
113	joko	1.2
114			# ... bless hash into object using classname
115			bless $self, $class;
116	joko	1.3
117			# remember the caller
118	joko	1.6	$self->{__bridge}->{caller_module} = caller;
119	joko	1.3	#print Dumper(caller(2));
120			#exit;
121
122	joko	1.6	$self->{__bridge}->{class_name} = $classname;
123
124			# patches for backward compatibility
125			$self->{'__arg'} = $self->{__bridge}->{'arg'} if $self->{__bridge}->{'arg'};
126			$self->{'__caller'} = $self->{__bridge}->{caller_module} if $self->{__bridge}->{caller_module};
127			$self->{'__classname'} = $self->{__bridge}->{class_name} if $self->{__bridge}->{class_name};
128	joko	1.3
129	joko	1.2	$self->_init() if $self->can('_init');
130	joko	1.5	$self->constructor() if $self->can('constructor');
131	joko	1.6
132			# trace
133			#print Dumper($self);
134			#exit;
135	joko	1.3
136	joko	1.2	return $self;
137			}
138	joko	1.1
139			sub _abstract_function {
140			my $self = shift;
141			my $self_classname = ref $self;
142			my $function_name = shift;
143			# was:
144	joko	1.7	$self->log_basic( __PACKAGE__ . ": function '$function_name' is an abstract method, please implement it in '$self_classname'.", 'warning');
145	joko	1.1	# is:
146	joko	1.3	#die( __PACKAGE__ . ": Function '$function_name' is an abstract method, please implement it in '$self_classname'.");
147	joko	1.1	#exit;
148	joko	1.3	}
149
150			sub fromPackage {
151			my $self = shift;
152			#my $self_classname = ref $self;
153			my $pkgname = shift;
154			my @args = @_;
155			# my $args = shift;
156
157			# my $caller = $self->{'__caller'};
158
159			#print Dumper($args);
160
161	joko	1.7	$self->log_basic( __PACKAGE__ . "->fromPackage( pkgname $pkgname args @args )", 'debug');
162	joko	1.3
163			# perl-load
164			my $evstring = "use $pkgname;";
165			eval($evstring);
166
167			# report errors
168			if ($@) {
169			# build error-messages
170	joko	1.8	my $issuer = __PACKAGE__ . ':' . __LINE__;
171			my $errmsg_native = "Error in eval: " . $@;
172	joko	1.3	#my $classname = $self->{__classname};
173			my $errmsg_critical = '';
174			if ($errmsg_native =~ m/Can't locate (.+?) in \@INC/) {
175	joko	1.7	$errmsg_critical = "Could not instantiate object from package '$pkgname' ('$1' not found).";
176	joko	1.3	} else {
177			$errmsg_critical = $errmsg_native;
178			}
179			# write error to logging-output (console\|file\|database)
180	joko	1.8	$self->log_basic( $errmsg_native . " (issuer='$issuer', code='$evstring')", 'debug' );
181	joko	1.7	$self->log_basic( $errmsg_critical, 'warning' );
182	joko	1.3	return;
183			}
184
185			# object-creation
186			my $object = $pkgname->new(@args);
187
188	joko	1.9	# trace
189			#print Dumper($object);
190
191	joko	1.3	# run boot-methods on object
192			$object->_init() if $object->can('_init');
193	joko	1.5	$object->constructor() if $object->can('constructor');
194	joko	1.3
195			return $object;
196	joko	1.1	}
197
198	joko	1.7	sub log_basic {
199			my $self = shift;
200			my $message = shift;
201			my $level = shift;
202	joko	1.8
203			#return;
204			$level \|\|= 'info';
205	joko	1.7
206	joko	1.9	my $notSoGood = ($level =~ /warning\|error\|critical/);
207
208			# STDERR?
209			if ($level && $notSoGood) {
210			print STDERR $level, ": ", $message, "\n";
211			}
212
213			# STDOUT?
214			if ($_dp_globals->{TRACE} \|\| $notSoGood) {
215	joko	1.7	print $level, ": ", $message, "\n";
216			}
217
218			# get logger instance
219			if (!$_dp_globals->{logger}) {
220			$_dp_globals->{logger} = eval { Log::Dispatch::Config->instance; };
221			}
222
223			if ($_dp_globals->{logger}) {
224	joko	1.8	$_dp_globals->{logger}->log( level => $level, message => $message);
225	joko	1.7	#} else {
226			#print $level, ": ", $message, "\n";
227			}
228
229			}
230
231	joko	1.1	1;
232	joko	1.7	__END__
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