NAME

       Tangram::Type - mapping individual fields

DESCRIPTION

       Tangram's persistent type system is extensible, allowing you to mount your own types and make them
       persistent. All you have to do is to register your type and provide mapping code. See
       Tangram::Type::Extending.

       Tangram comes with built-in support for the following types:

       Simple Scalar types
           Supported are strings, integers, real numbers and dates.  More types of this ilk are easily added.

           "string", "int", "real": see Tangram::Type::Scalar

           "date", "time", "datetime", "dmdatetime": see "Date/Type/Date/DateTime" in Tangram::Type

       Compound Structure types
           "perl_dump": see Tangram::Type::Dump::Perl.  A "perl_dump" structure may contain any structure which
           Data::Dumper can dump successfully.

           "storable": see Tangram::Type::Dump::Storable.  Very much like "perl_dump", but implemented via the
           `Storable' serialisation engine.

           "yaml": see Tangram::Type::Dump::YAML.  Very much like "perl_dump", but implemented via the `YAML'
           serialisation engine.  Doesn't currently work, due to inadequacies in the current Perl YAML
           implementation.

           NEW in Tangram 2.08:

           "idbif": see Tangram::Type::Dump::Any.  Like the above, but can combine multiple object properties
           into a single database column.

       `Flat' Array & Hash types
           Note: these are only actually required if you need to be able to query on individual fields inside
           the array/hash - otherwise, the "perl_dump" or "idbif" mapping is a lot faster and more flexible.

           "flat_array": see "Array/Scalar" in Tangram::Type

           "flat_hash": see "Hash/Scalar" in Tangram::Type

       References to other objects
           "ref": see Tangram::Type::Ref::FromMany (implementing an N to 1 relationship, in which any object can
           be the referant)

       Sets of other objects
           Set relationships are closest to the main type of relationship used in an RDBMS.  Avid CompSci
           students will know that the relational database model is based heavily on `Set Theory', which is a
           subset of a more general concept of `Categories' - generic couplings of a number of classes.

           In Perl space, these collections are represented via the Set::Object module.  Sets may not have
           duplicate elements, and cannot contain undef values.

           "set": see Tangram::Type::Set::FromMany (implementing an unordered N to N relationship, with all
           objects sharing a common base class)

           "iset": see Tangram::Type::Set::FromOne (implementing an unordered 1 to N relationship, with all
           objects sharing a common base class)

       Arrays of other objects
           The addition to Sets, you can have `Arrays' of objects, represented by a standard Perl array in
           memory.  Arrays may contain undef values (in the middle of the list), and the "array" type may
           contain duplicates (ie, the same element present in separate places in the list).

           "array" : see Tangram::Type::Array::FromMany (implementing an ordered N to N relationship, with all
           objects sharing a common base class)

           "iarray": see Tangram::Type::Array::FromOne (implementing an ordered 1 to N relationship, with all
           objects sharing a common base class)

       Hashes of other objects
           Much like the Array types, the Hash types are indexed via a string value, and represented as a Perl
           hash in memory.  These hashes may not contain undef values (those are dropped).  The "hash" type may
           contain duplicate elements.

           "hash" : see Tangram::Type::Hash::FromMany (implementing a keyed N to N relationship, with all
           objects sharing a common base class)

           "ihash": see Tangram::Type::Hash::FromOne (implementing a keyed 1 to N relationship, with all objects
           sharing a common base class)