I happen to be struggling with Class::DBI and date formats, but that's not what my question is about. I'll use my existing code for the sake of concreteness, but it's actually a question about Perl classes. The short version of the question is "how can I refer to 'the method I'm overriding' from within a method declaration in a package?"

Before querying my database for anything, I need to set NLS_DATE_FORMAT. It's possible that someone else needed to use a different format, so I should set it myself before every call, and reset it (to be polite). Don't be too mean about what a bad idea this is (I should probably use triggers); it's just the example to show my point.

Empirically, I've found that the following does what I want:

package MyDateExperiment ;
use base qw/Class::DBI/ ;
use Class::DBI::Plugin::DateFormat::Oracle qw(0.01) ;
my $NLS_DATE_FORMAT_CONVENTIONAL = 'YYYY-MM-DD HH24:MI:SS' ;
#
# connection stuff...
# name the table...
# field definitions...
#
sub create {
  my $class = shift ;
  my $oldFormat = $class->get_nls_date_format;
  $class->set_nls_date_format( $NLS_DATE_FORMAT_CONVENTIONAL ) ;
  my $ans = $class->SUPER::create( @_ ) ;
  $class->set_nls_date_format( $oldFormat ) ;
  return $ans ;
}
sub get {
  my $class = shift ;
  my $oldFormat = $class->get_nls_date_format;
  $class->set_nls_date_format( $NLS_DATE_FORMAT_CONVENTIONAL ) ;
  my $ans = $class->SUPER::get( @_ ) ;
  $class->set_nls_date_format( $oldFormat ) ;
  return $ans ;
}

sub set {
  my $class = shift ;
  my $oldFormat = $class->get_nls_date_format;
  $class->set_nls_date_format( $NLS_DATE_FORMAT_CONVENTIONAL ) ;
  my $ans = $class->SUPER::set( @_ ) ;
  $class->set_nls_date_format( $oldFormat ) ;
  return $ans ;
}
[download]

Now, I'm "smart" enough to see that create, get, and set are pretty similar and I'd prefer to be lazy. So I poke around and decide that this is what I'd prefer:

foreach my $meth (qw/create get set/) {
  no strict qw/refs/ ;
  *{__PACKAGE__ . "::$meth"} = sub {
    my $class = shift ;
    my $oldFormat = $class->get_nls_date_format;
    $class->set_nls_date_format( $NLS_DATE_FORMAT_CONVENTIONAL ) ;
    my $ans = _good_lord_what_function( @_ ) ; ### ???
    $class->set_nls_date_format( $oldFormat ) ;
    return $ans ;
  }
}
[download]

This "works" in that it defines the methods and they get called properly, but it's two hours later and I've got no idea how to call the superclass's "$meth" method when all I know is the string "$meth". Things I've tried (paraphrasing, because I didn't keep good track of all the experiments) include:

• Capture the original method before creating a new one:

    no strict qw/refs/ ;
    my $originalFunction = \&{__PACKAGE__ . "::$meth" } ;
    *{__PACKAGE__ . "::$meth"} = sub {
  ...
       my $ans = $originalFunction->( $class, @_ ) ;
  ...
    }
  [download]

• Ask the superclass for the right method:

  ...
       my ($papa) = Class::ISA::super_path($class) ;
       my $papaMethod = $papa->can($meth) ;
       my $ans = $papaMethod->($papa, @_ ) ;
  ...
  [download]

• Just type and hope Perl will do what I want:

  ...
      my $ans = $class->SUPER::{"$meth"}( @_ ) ;
  ...
  [download]

There were others. Each failed in its own way (some aren't even syntactic). Can someone tell me the way I should have done it?

Thanks,

dave

---

---

Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!

Titles consisting of a single word are discouraged, and in most cases are disallowed outright.

Read Where should I post X? if you're not absolutely sure you're posting in the right place.

Please read these before you post! —

• How do I compose an effective node title?
• How do I post a question effectively?
• Markup in the Monastery

Posts may use any of the Perl Monks Approved HTML tags:

a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr

You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)

	For:		Use:
	&		&
	<		&lt;
	>		&gt;
	[		&#91;
	]		&#93;

Link using PerlMonks shortcuts! What shortcuts can I use for linking?

See Writeup Formatting Tips and other pages linked from there for more info.