libs/DesignPattern/Object.pm

## ---------------------------------------------------------------------------
##  $Id: Object.pm,v 1.7 2003/02/18 18:34:35 joko Exp $
## ---------------------------------------------------------------------------
##  $Log: Object.pm,v $
##  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);

  # 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';

  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 => $level, message => $message);
  #} else {
    #print $level, ": ", $message, "\n";
  }
  
}

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