/ 
OP-0.310_001
/ OP

NAME

OP - Compact prototyping of InnoDB-backed object classes

VERSION

This documentation is for version 0.310_001 of OP.

STATUS

The usual pre-1.0 warnings apply. Consider this alpha code. It does what we currently ask of it, and maybe a little more, but it is a work in progress.

SYNOPSIS

use strict;
use warnings;

use OP;

create "YourApp::YourClass" => { };

See PROTOTYPE COMPONENTS in OP::Class for detailed examples.

A cheat sheet, ex/cheat.html, is included with this distribution.

DESCRIPTION

OP is a Perl 5 framework for prototyping InnoDB-backed object classes.

This document covers the high-level concepts implemented in OP.

FRAMEWORK ASSUMPTIONS

When using OP, as with any framework, a number of things "just happen" by design. Trying to go against the flow of any of these base assumptions is not recommended.

Configuration

See CONFIGURATION AND ENVIRONMENT in this document.

Classes Make Tables

The core function of OP is to derive database tables from the assertions contained in object classes. OP creates the tables that it needs.

If, rather, you need to derive object classes from a database schema, you may want to take a look at Class::DBI and other similar packages on the CPAN, which specialize in doing just that.

OP::ForeignTable may be used to work with external datasources as if they were OP classes, but this functionality is quite limited.

Default Base Attributes

Database-backed OP objects always have "id", "name", "ctime", and "mtime".

  • id => OP::ID

    id is the primary key at the database table level. The gets used in database table indexes, and should generally not be altered once assigned.

    Base64-encoded Globally Unique IDs are used by default, though it is possible to assert any scalar OP object class for the id column. See OP::ID, OP::Serial.

  • name => OP::Name

    name is a secondary human-readable key.

    The assertions for the name attribute may be changed to suit a class's requirements, and the name value for any object may be freely changed.

    For more information on named objects, see OP::Name.

  • ctime => OP::DateTime

    ctime is the Unix timestamp representing the object's creation time. OP sets this when saving an object for the first time.

    For more information on timestamps, see OP::DateTime.

  • mtime => OP::DateTime

    mtime is the Unix timestamp representing the object's last modified time. OP updates this each time an object is saved.

undef Requires Assertion

Undefined values in objects translate to NULL in the database, and OP does not permit this to happen by default.

Instance variables may not be undef, (and the corresponding table column may not be NULL), unless the instance variable was explicitly asserted as optional in the class prototype. To do so, provide "optional" as an assertion argument, as in the following example:

create "YourApp::Example" => {
  ### Do not permit NULL:
  someMandatoryDate => OP::DateTime->assert,

  ### Permit NULL:
  someOptionalDate => OP::DateTime->assert(
    subtype(
      optional => true,
    )
  ),

  # ...
};

Namespace Matters

OP's core packages live under the OP:: namespace. Your classes should live in their own top-level namespace, e.g. "YourApp::". This will translate (in lower case) to the name of the app's database. The database name may be overridden by implementing class method databaseName.

Namespace elements beyond the top-level translate to lower case table names. In cases of nested namespaces, Perl's "::" delineator is swapped out for an underscore (_). The table name may be overriden by implementing class method tableName.

create "YourApp::Example::Foo" => {
  # overrides default value of "yourapp"
  databaseName => sub {
    my $class = shift;

    return "some_legacy_db";
  },

  # overrides default value of "example_foo"
  tableName => sub {
    my $class = shift;

    return "some_legacy_table";
  },

  # ...
};

OBJECT TYPES

OP object types are used when asserting attributes within a class, and are also suitable for instantiation or subclassing in a self-standing manner.

The usage of these types is not mandatory outside the context of creating a new class-- OP always returns attributes from the database in object form, but these object types are not a replacement for Perl's native data types in general usage, unless the developer wishes them to be.

These modes of usage are shown below, and covered in greater detail in specific object class docs.

DECLARING AS SUBCLASS

By default, a superclass of OP::Node is used for new classes. This may be overridden using __BASE__:

use OP;

create "YourApp::Example" => {
  __BASE__ => "OP::Hash",

  # ...
};

ASSERTING AS ATTRIBUTES

When defining the allowed instance variables for a class, the assert() method is used:

#
# File: Example.pm
#
use OP;

create "YourApp::Example" => {
  someString => OP::Str->assert,
  someInt    => OP::Int->assert,

};

INSTANTIATING AS OBJECTS

When instantiating, the class method new() is used, typically with a prototype object for its argument.

#
# File: somecaller.pl
#
use strict;
use warnings;

use YourApp::Example;

my $example = YourApp::Example->new(
  name       => "Hello",
  someString => "foo",
  someInt    => 12345,
);

$example->save("Saving my first object");

$example->print;

IN METHODS

Constructors and setter methods accept both native Perl 5 data types and their OP object class equivalents. The setters will automatically handle any necessary conversion, or throw an exception if the received arg doesn't quack like a duck.

To wit, native types are OK for constructors:

my $example = YourApp::Example->new(
  someString => "foo",
  someInt    => 123,
);

#
# someStr became a string object:
#
say $example->someString->class;
# "OP::Str"

say $example->someString->size;
# "3"

say $example->someString;
# "foo"

#
# someInt became an integer object:
#
say $example->someInt->class;
# "OP::Int"

say $example->someInt->sqrt;
# 11.0905365064094

say $example->someInt;
# 123

Native types are OK for setters:

$example->setSomeInt(456);

say $example->someInt->class;
# "OP::Int"

ABSTRACT CLASSES & MIX-INS

OBJECT TYPES

The basic types listed here may be instantiated as objects, or asserted as inline attributes.

CONSTANTS & ENUMERATIONS

HELPER MODULES

TOYS & TOOLS

  • bin/opconf - Generate an .oprc on the local machine

  • bin/oped - Edit OP objects using VIM and YAML

  • bin/opid - Dump OP objects to STDOUT in various formats

  • bin/opsh - Interactive and persistent Perl 5 shell

EXPERIMENTAL

Experimental classes are subject to radical upheaval, questionable documentation, and unexplained disappearances. They represent proof of concept in their respective areas, and may move out of experimental status at some point.

INFOMATICS

The infomatics classes are an attempt to replicate certain functionality of RRD using SQL and Perl.

FOREIGN DB ACCESS

Foreign DB access classes are similar in function to Class::DBI, in that they are used to derive object classes from existing schemas. This is an inversion of how OP normally functions, since OP was designed to derive schemas from classes.

BULK TABLE WRITER

The Bulk writer provides an alternate method for saving objects, utilizing MySQL's LOAD FILE syntax.

CONFIGURATION AND ENVIRONMENT

OP_HOME + .oprc

OP needs to be able to find a valid .oprc file in order to bootstrap itself. This lives under $ENV{OP_HOME}, which defaults to the current user's home directory.

To generate a first-time config for the local machine, copy the .oprc (included with this distribution) to the proper location, or run bin/opconf (also included with this distribution) as the user who will be running OP. This is a post-install step which is not currently handled by make install.

See OP::Constants for information regarding customizing and extending the local rc file.

OP + mod_perl

OP-based classes used in a mod_perl app should be preloaded by a startup script. OP_HOME must be set in the script's BEGIN block.

For example, in a file startup.pl:

use strict;
use warnings;

BEGIN {
  $ENV{OP_HOME} = '/home/user/op'; # Directory with the .oprc
}

use MyApp::Component;
use MyApp::OtherComponent;

1;

And in your httpd.conf:

PerlRequire /path/to/your/startup.pl

SEE ALSO

OP::Class, ex/cheat.html

OP is on GitHub: http://github.com/aayars/op

AUTHOR

Alex Ayars <pause@nodekit.org>

COPYRIGHT

 File: OP.pm

 Copyright (c) 2009 TiVo Inc.

 All rights reserved. This program and the accompanying materials
 are made available under the terms of the Common Public License v1.0
 which accompanies this distribution, and is available at
 http://opensource.org/licenses/cpl1.0.txt