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Tangram::Type(3) |
User Contributed Perl Documentation |
Tangram::Type(3) |
Tangram::Type - mapping individual fields
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 seperate
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)
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