Patch for fields.pm (Was: Re: On Pseudohashes)

[Peter Scott <Peter@PSDT.com>]

Nervous as I am about bringing up pseudo-hashes at this point, I wish to 
offer the following patch for 5.005_63, which puts a convenience function 
in fields.pm that creates a pseudo-hash for those who don't want to type 
the natural numbers and make sure the pairs match up.

The interface came out of a discussion with Damian Conway where I evinced 
this desire, we kicked around ideas like qp//, and he eventually suggested 
this interface and said y'all could blame him for it :-)  (But not for the 
idea itself or its implementation.)  The only change I made to the 
interface was to shorten the name since it cannot be exported as Damian 
recommended or it would be treated as a field.  Perhaps because of that it 
ought to live in another module, but I can't see where.

--- lib/fields.pm	Fri Jan 14 17:15:56 2000
+++ lib/fields.pm.orig	Tue Jul 20 10:18:01 1999
@@ -24,18 +24,6 @@
          use fields qw(baz _private);  # not shared with Foo
      }

-    # Pseudo-hash initialization only:
-    use fields;
-    $pseu = fields::ph(dog => 'bark', cat => 'meow', bird => 'tweet');
-
-    $pseu = fields::ph(%hash);
-
-    @keys = qw(cat dog bird frog);
-    $pseu = fields::ph(\@keys);
-
-    @vals = qw(meow bark chirp ribbit);
-    $pseu = fields::ph(\@keys, \@vals);
-
  =head1 DESCRIPTION

  The C<fields> pragma enables compile-time verified class fields.  It
@@ -73,25 +61,6 @@
        $self;
    }

-C<fields::ph> creates and initializes a pseudo-hash from arguments.
-This is for when you want to create a pseudo-hash explicitly and don't
-want to count the indices on your fingers, i.e., rather than type
-
-  $sound = [{ cat => 1, dog => 2, bird => 3 }, 'meow', 'bark', 'tweet'];
-
-you can type
-
-  $sound = fields::ph(cat => 'meow', dog => 'bark', bird => 'tweet');
-
-If the first argument is a reference to an array, the pseudo-hash will
-be created with keys from that array, and if there is a second argument,
-it must also be a reference to an array of the same size whose elements
-will be used as the values.  That makes it particularly useful for
-hashifying subroutine arguments:
-
-  sub dogtag {
-     my $tag = fields::ph([qw(name rank ser_num)], [@_]);
-  }

  =head1 SEE ALSO

@@ -182,32 +151,6 @@
           print "\n";
        }
     }
-}
-
-sub ph {
-   my (%h, $i);
-   my $v = [];
-   if (@_ and ref $_[0] eq 'ARRAY') {
-      my $a = shift;
-      @h{@$a} = 1 .. @$a;
-      if (@_) {
-         $v = shift;
-         unless (! @_ and ref $v eq 'ARRAY' and @$v == @$a) {
-            require Carp;
-            Carp::croak ("Expected at most two refs to equal size arrays\n");
-         }
-      }
-   }
-   else {
-      if (@_ % 2) {
-         require Carp;
-         Carp::croak ("Odd number of elements initializing pseudo-hash 
from hash\n");
-      }
-      $i = 0;
-      @h{grep ++$i % 2, @_} = 1 .. @_ / 2;
-   }
-   $i = 0;
-   [ \%h, @_ ? grep $i++ % 2, @_ : @$v ];
  }

  1;
--- t/lib/fields.t	Wed Jan 12 15:33:15 2000
+++ t/lib/fields.t.orig	Wed Jan 12 15:00:38 2000
@@ -82,7 +82,7 @@
      'Foo::Bar::Baz' => 'b1:1,b2:2,b3:3,foo:4,bar:5,baz:6',
  );

-print "1..", int(keys %expect)+9, "\n";
+print "1..", int(keys %expect)+5, "\n";
  my $testno = 0;
  while (my($class, $exp) = each %expect) {
     no strict 'refs';
@@ -109,24 +109,8 @@
  print "not " unless $@ && $@ =~ /^No such pseudo-hash field "notthere"/;
  print "ok ", ++$testno, "\n";

-my $ph = fields::ph(a => 1, b => 2, c => 3);
-print "not " unless fstr($ph) eq 'a:1,b:2,c:3';
-print "ok ", ++$testno, "\n";
-
-$ph = fields::ph([qw/a b c/], [1, 2, 3]);
-print "not " unless fstr($ph) eq 'a:1,b:2,c:3';
-print "ok ", ++$testno, "\n";
-
-eval '$ph = fields::ph([qw/a b c/], [1])';
-print "not " unless $@ && $@ =~ /^Expected at most/;
-print "ok ", ++$testno, "\n";
-
-eval '$ph = fields::ph("odd")';
-print "not " unless $@ && $@ =~ /^Odd number of/;
-print "ok ", ++$testno, "\n";
-
-
  #fields::_dump();
+
  # check if
  {
      package Foo;



--
Peter Scott
Pacific Systems Design Technologies

---

References to:

Raphael Manfredi <Raphael.Manfredi@st.com>
Tom Christiansen <tchrist@chthon.perl.com>

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