Class DatabaseTuple

Wraps the return data from a DB-API fetch*() method.

Instances of this class are used to represent tuples of information,
typically returned by a database query. A TupleDescriptor is used as
a means of describing the information for a variety of access methods.
The tuple's information can be accessed via simple indexing, slices,
as a mapping where the keys are the column names (as defined by the
descriptor), or via attribute-based access (where the attribute names
are equivalent to the column names).

This object acts as a tuple, a list, a mapping, and an instance. To
retrieve "pure" tuples, lists, or mappings, the asTuple(), asList(),
and asMapping() methods may be used, each returning a value equal to
what this object pretends to be.

There exists a potential ambiguity between attempting to act as a list
or mapping and the attribute-based access to the data. In particular,
if the column names are 'index', 'count', 'keys', 'items', 'values', or
'has_key', then the attribute-based access will have precedence over
their related methods for lists and mappings. To actually use these
methods, simply apply them to the result of the asList() or asMapping()
methods.

Note that column names with leading underscores may interfere with
the implementation of this class, and as a result may not be accessible
via the attribute-access scheme. Also, column names of asTuple, asList,
and asMapping will be inaccessible via the attribute-access scheme
since those will always represent the methods. To access these columns,
the mapping interface can be used with the column name as the mapping
key.

Note that a database tuple acts as a tuple with respect to sub-scripted
assignment. TypeError exceptions will be raised for several situations,
and AttributeError may be raised for some methods that are intended
to mutate the data (list's 'sort' method) as these methods have not
been implemented.

DatabaseTuple constructor.

A DatabaseTuple is initialized with a TupleDescriptor and a tuple or
list specifying the data elements.

Simulate attribute-access via column names

Simulate indexed (tuple/list) and mapping-style access

Simulate list/tuple slicing access

Simulate attribute-access via column names

Simulate indexed (tuple/list) and mapping-style access

Simulate list/tuple slicing access

Simulate list's methods

Internal method for named-based value retrieval

Simulate mapping's methods

Simulate list's methods

Simulate mapping's methods

Simulate mapping's methods

Return the "list" as a real mapping

Return the "tuple" as a real mapping

Return the "tuple" as a real tuple