in reply to EZDBI is an easier interface to SQL databases

Here's the equivalent code using Class::Tangram: 
#--------------------------------------------------------
# define "Person" objects
package Person;

use base qw(Class::Tangram);
$schema = {
    table => "names",
    fields => {
        string => [ qw(first last) ]
    }
};

#--------------------------------------------------------
# define which objects we have in our database
package Project;
use Tangram::Relational;
$dbschema = Tangram::Relational->schema
     ({ classes => [ 'Person' => $Person::schema ]});

sub schema { $dbschema };

#--------------------------------------------------------
#  the main program
package main;

# connect to the database.
my $storage = Tangram::Relational->connect(Project->schema,
                                           $dsn, $u, $p);

# insert a new Person
$storage->insert(Person->new( first => "Harry",
                              last => "Potter" ));

# $remote_person refers to a person in the database,
# for select queries.
my $remote_person = $storage->remote("Person");

if ($storage->select
       ( $remote_person,
         $remote_person->{first} eq "Harry" )) {
   print "Potter is IN THE HOUSE.\n";
}

# iterate through all rows
for my $person ($storage->select("Person")) {
    print $person->last.": ".$person->first."\n";
}

# delete every row matching "Potter"
$storage->erase
    ($storage->select
        ( $remote_person,
          $remote_person->{last} eq "Potter" ));
 
if ($storage->select
       ( $remote_person,
         $remote_person->{last} eq "Potter" )) {
   die "Can't get rid of that damn Harry Potter!";
}

[download]

Tangram is very cool. Check out the guided tour. Once you divorce yourself from the concept of tables and rows and start thinking in terms of objects, life becomes a lot easier...

Replies are listed 'Best First'.
Re: EZDBI is an easier interface to SQL databases
by Dominus (Parson) on Oct 11, 2001 at 19:55 UTC
    mugwumpjism says:
    Once you divorce yourself from the concept of tables and rows and start thinking in terms of objects, life becomes a lot easier...
    Maybe you could elaborate on why you think so. From here, looking at the 30-line program that you wrote that is "equivalent code" for my 11-line program, the reasons are far from obvious.

    What's the benefit that justifies a 2-3x increase in code size?

    --
    Mark Dominus
    Perl Paraphernalia

[reply]
      Maybe you could elaborate on why you think so. From here, looking at the 30-line program that you wrote that is "equivalent code" for my 11-line program, the reasons are far from obvious.

      What's the benefit that justifies a 2-3x increase in code size?

      I agree that it doesn't necessarily make life any easier, and the code increase (line count-wise) is alot less extreme if you ignore the Tangram schema setup and the comments and the line breaks for readability. But the benefit is that its a tool for 'object persistence'. Which puts Tangram and EZDBI in entirely different categories anyway. But I do appreciate the examples of both :)

      Update:Re: Dominus's reply - I also said 'ignoring the Tangram ... setup', which is everything up to the 'package main'. Which you can count or not. I figure there's an argument for not counting it since its a constant that, once set up, you can do as much inserting/deleting/updating/selecting as you like. So IF you don't count it, then the amount of code is not much greater.

      Since the original program didn't have any objects, I don't see how that could be a benefit in this case.

      That was my point, the two modules are for entirely different things :) Making DBI EZ or storing objects in a database. And how can you say its not a benefit in this case just because your script didn't have any objects. I kind of think of Harry Potter as an object :)
      Besides, if you're going to make that sort of argument, then I submit that this script is far superior:

      use HarryPotter;

InsertHarryPotter();
IsPotterInTheHouse();
PrintHarry() for SelectPotter();
DeletePotter();
SelectPotter() and DamnPotter();

      [download]
[reply]
[d/l]
        Says runrig:
        the code increase (line count-wise) is alot less extreme if you ignore the Tangram schema setup and the comments and the line breaks for readability.
        I did ignore the comments and the line breaks. Whether you count them or not, it is still three times as long.

        the benefit is a tool for 'object persistence'
        Since the original program didn't have any objects, I don't see how that could be a benefit in this case.

        --
        Mark Dominus
        Perl Paraphernalia

[reply]

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