How to dynamically (yet structurally) creat a hohohohoh

princepawn has asked for the wisdom of the Perl Monks concerning the following question:

I wrote some code to take this file:

File:         02packages.details.txt
URL:          http://www.perl.com/CPAN/modules/02packages.details.txt
Description:  Package names found in directory $CPAN/authors/id/
Columns:      package name, version, path
Intended-For: Automated fetch routines, namespace documentation.
Written-By:   mldistwatch (v 2.343) by Andreas.Koenig@anima.de
Line-Count:   14257
Last-Updated: Mon, 28 Oct 2002 14:53:05 GMT

A::B                              undef  M/MA/MARCEL/Devel-SearchINC-0
+.01.tar.gz
Aardvark                          undef  D/DU/DUNCAND/CGI-Portable-0.4
+7.tar.gz
abbreviation                       0.02  M/MI/MIYAGAWA/abbreviation-0.
+02.tar.gz
ABI                                0.01  M/MA/MALAY/ABI-0.01.tar.gz
about                             undef  S/SH/SHERWOOD/xisofs-1.3.tar.
+gz
Ace                                1.83  L/LD/LDS/AcePerl-1.83.tar.gz
Ace::Browser::AceSubs              1.21  L/LD/LDS/AcePerl-1.83.tar.gz
Ace::Browser::GeneSubs            undef  L/LD/LDS/AcePerl-1.83.tar.gz
Ace::Browser::SearchSubs          undef  L/LD/LDS/AcePerl-1.83.tar.gz
Ace::Browser::SiteDefs            undef  L/LD/LDS/AcePerl-1.82.tar.gz
Ace::Browser::TreeSubs            undef  L/LD/LDS/AcePerl-1.83.tar.gz
Ace::Freesubs                      1.00  L/LD/LDS/AcePerl-1.83.tar.gz
Ace::Graphics::Fk                 undef  L/LD/LDS/AcePerl-1.82.tar.gz
Ace::Graphics::Glyph              undef  L/LD/LDS/AcePerl-1.82.tar.gz
Ace::Graphics::Glyph::anchored_arrow undef  L/LD/LDS/AcePerl-1.82.tar.
+gz
Ace::Graphics::Glyph::arrow       undef  L/LD/LDS/AcePerl-1.82.tar.gz
Ace::Graphics::Glyph::box         undef  L/LD/LDS/AcePerl-1.83.tar.gz
[download]

and turn it into a hohohohohohoh:

my $data_line = qr/(\S+)\s+\S+\s+\S+\d+.tar.gz/;

use vars qw(%pkg);

sub build {
  my $file = shift;

  use FileHandle;

  my $fh = new FileHandle $file or die "couldnt open: $!";

  while (<$fh>) {
    next unless /$data_line/;
    my $pkg = $1;
    my @tree_struct = split '::', $pkg;
    @tree_struct = map { "'$_'" } @tree_struct;
    my $join = join '}{',  @tree_struct ;
    $join = "{$join}";
    my $eval = "\$pkg$join = '$pkg'";
    warn $eval;
    eval $eval;
  }

  use Data::Dumper;
  warn Dumper(\%pkg);

}
[download]

But I am leery of using eval and think that there must be some more structural as opposed to string-based method of creating my hohohohohohohoh

Comment on How to dynamically (yet structurally) creat a hohohohoh Select or Download Code

Replies are listed 'Best First'.
Re: How to dynamically (yet structurally) creat a hohohohoh by fruiture (Curate) on Oct 28, 2002 at 18:08 UTC
There was something quite similar yesterday... `my $tree = 'Foo::Bar::Baz'; my %pkg; my $ref = \%pkg; for(split /::/,$tree){ $ref = exists $ref->{$_} ? # we don't need no autivivification ( $ref->{$_} = {} ) : $ref->{$_} } use Data::Dumper; warn Dumper(\%pkg);` [download] Sometimes it's usefull if you've done linked lists in Pascal at school :) -- http://fruiture.de	[reply] [d/l]
Re: How to dynamically (yet structurally) creat a hohohohoh by tye (Sage) on Oct 28, 2002 at 20:25 UTC
Going way back to code from (tye)Re: varying length multi-dimensional hashes, I'd use: `my $ref= \\%pkg; for my $key ( split /::/, $pkg ) { $ref= \$$ref->{$key}; } $$ref= $pkg;` [download] in the middle of your code. - tye (I keep that filed away under "real use for \\")	[reply] [d/l]
Re: How to dynamically (yet structurally) creat a hohohohoh by broquaint (Abbot) on Oct 28, 2002 at 18:05 UTC
Several solutions to a problem similar to this can be found at this node. HTH `_________ broquaint`	[reply]
[OT] Re: How to dynamically (yet structurally) creat a hohohohoh by belden (Friar) on Oct 28, 2002 at 22:53 UTC
Just curious; you `use FileHandle;` within your code: why not `open my $fh, $file or die "$file: $!\n";` instead? I have a co-worker who (imo) over-uses FileHandle and Class::Struct where simply using open or a complex data structure a-la perlreftut would suffice. Both seem to slow his code down, without adding any degree of utility (clarity, maintainability, functionality). At least, in my eyes. When I get the chance to work on his code, I have to resist the urge to re-write all of the calls to FileHandle and Class::Struct so they "look right". Just because it isn't the way I'd do it doesn't mean it's wrong; it's different. fwiw, my co-worker likes to use FileHandle because he wants his code to be as object-oriented as possible. I'm not criticising you- I'm genuinely curious: why `use FileHandle;` in the code you posted? blyman setenv EXINIT 'set noai ts=2'	[reply] [d/l] [select]