[Bioperl-l] do not hate individual getter/setters coding?

[Heikki Lehvaslaiho]

Here comes an example of really complicated perl programming. At some
point, I did not have the bioperl emacs macros installed, so I "wrote"
this:

############### bioperl_method_template.pl ######################

#!/usr/bin/perl

$a = shift;
$a||= "FOO";

# the code on the first line should go into the standard new()

print  "

    \$$a && \$self->$a(\$$a);

=head2 $a

 Title   : $a
 Usage   : \$obj->$a();
 Function:

            Sets and returns the $a of the resource

 Example :
 Returns : string
 Args    : string

=cut


sub $a {
    my (\$self,\$value) = \@_;
    if( defined \$value) {
        \$self->{'_$a'} = \$value;
    }
   return \$self->{'_$a'};
}


";

#################################################################



Enjoy,

	-Heikki


On Mon, 2003-01-20 at 14:08, Jason Stajich wrote:
> This discussion has been had.
> 
> See the following for example and read the whole set of threads.
> http://bioperl.org/pipermail/bioperl-l/2002-November/010208.html
> 
> You are welcome to implement your code with AUTOLOAD (in fact you'll see
> the bioperl-run objects often support this), but many of us have our
> reasons for not wanting to use it all the time.
> 
> Most importantly, get/set methods should be implemented properly
> allowing resetting of the value to undef as outlined in one of the posts
> and now as provided in the bioperl.lisp emacs template for code
> generation.
> 
> Best,
> -jason
> On Wed, 15 Jan 2003, Xiao Juguang wrote:
> 
> > Hi guys,
> >
> > I may be a very lazy coder, so that I was tired on writing tedious
> > getter/setters fragment, as well, as a source code reader, I felt bored
> > to read individule getter/setters occupying, sometimes, more than half
> > of module. Do you? I thought bioperl follows Perl's neat soul and Perl
> > hopes its features to be fully used. Should we just suggest to add 2
> > subs in Bio::Root::Root ? _autoload_methods and AUTOLOAD . They look
> > like this.
> >
> >
> > =head2 _autoload_methods
> >
> > This subroutine is usually invoked at the very beginning line of constructor,
> > to set subroutine names for getter and setters.
> >
> > SYNOPSIS
> >
> > sub new{
> >     my ($class, @args) = @_;
> >     my $self = $class->SUPER::new(@args);
> >
> >     $self->_autoload_methods([qw(dbhost dbname dbuser dbpass)]); # Don't add if unnecessary.
> >
> >     # Then, say
> >
> >     my ($dbhost) = $self->_rearrange([qw(DBHOST)], @args);
> >     $self->dbhost($dbhost);
> >
> >     return $self;
> > }
> >
> > =cut
> >
> > sub _autoload_methods {
> >     my ($self, $arg) = @_;
> >     if(defined $arg && ref($arg) eq 'ARRAY'){
> > #        $self->{_autoload_methods} = $arg;
> >         push @{$self->{_autoload_methods}}, @{$arg};
> >
> >         # equally explicitly declare the subs !!!
> >         use subs @{$self->{_autoload_methods}};
> >     }
> >     return $self->{_autoload_methods};
> > }
> >
> > sub AUTOLOAD{
> >     return if our $AUTOLOAD =~ /::DESTROY$/;
> >     my ($self, $arg) = @_;
> >     my $field = $AUTOLOAD;
> >     $field =~ /::([\w\d]+)$/;
> >     if($self->_autoload_methods && grep /$1/, @{$self->_autoload_methods}){
> >         $self->{$field} = $arg if defined $arg;
> >         return $self->{$field};
> >     }else{
> >         $self->throw("Can't find the method '$field'");
> >     }
> > }
> >
> >
> > I remembered in this mailing list, there was a discussion on it. However,  I forgot the harm to use it that people mention. In theory, Bio::Root::Root::AUTOLOAD will be almost last visited in the path of method searching. I just quote paragraphs from Programming Perl 3rd Ed. by Larry Wall, for your information.
> >
> > When your invoke a method 'methname' on an invocant of type 'classname', Perl tries six different ways to find a subroutine to use:
> > 1. First, Perl looks in the invocant's own package for a subroutine named classname::methname. If that fails, inheritance kicks in, and we go to step 2.
> > 2. Next, Perl checks for methods inherited from base classes by looking in all the parent packages listed in @classmane::ISA for a parent::methname subroutine. The search is left-to-right, recurive, and depth-first. The recursion assures that grandparent classes, great-grandparent classes, great-great-grandparent classes, and so on, are all searched.
> > 3. If that fails, Perl looks for a subroutine named UNIVERSAL::methname.
> > 4. At this point, Perl gives up on methname and starts looking for an AUTOLOAD. First, it looks for a subroutine named classname::AUTOLOAD.
> > 5. Failing that, Perl searches all parent packages listed in @classname::ISA, for any parent::AUTOLOAD subroutine. The search is again left-to-right, recurive, and depth-first.
> > 6. Finally, Perl looks for a subroutine named UNIVERSAL::AUTOLOAD.
> > Perl stops after the first successful attempt and invokes that subroutine.
> >
> > To make perldoc friendly, developer should write pod for each 'virtual getter/setter' or might write a =head2 item for a group of get/setters. It is also Perl itself friendly. I mean, since we 'use subs @{$self->{_autoload_methods}};', Perl regards them 'virtual' subs as real ones.
> >
> > My $0.0000002 worth.
> >
> > Please do correct me or my code. Thanks.
> >
> > Juguang.
> >
> >
> > _______________________________________________
> > Bioperl-l mailing list
> > Bioperl-l@bioperl.org
> > http://bioperl.org/mailman/listinfo/bioperl-l
> >
> 
> --
> Jason Stajich
> Duke University
> jason at cgt.mc.duke.edu
> _______________________________________________
> Bioperl-l mailing list
> Bioperl-l@bioperl.org
> http://bioperl.org/mailman/listinfo/bioperl-l
-- 
______ _/      _/_____________________________________________________
      _/      _/                      http://www.ebi.ac.uk/mutations/
     _/  _/  _/  Heikki Lehvaslaiho          heikki@ebi.ac.uk
    _/_/_/_/_/  EMBL Outstation, European Bioinformatics Institute
   _/  _/  _/  Wellcome Trust Genome Campus, Hinxton
  _/  _/  _/  Cambs. CB10 1SD, United Kingdom
     _/      Phone: +44 (0)1223 494 644   FAX: +44 (0)1223 494 468
___ _/_/_/_/_/________________________________________________________