pyre.records.Record

Module Contents

class pyre.records.Record.Record

Bases: pyre.framework.Dashboard.Dashboard

The base class for representing data extracted from persistent stores.

Records have field descriptors that provide the information necessary to convert data between the representation used by the persistent store and the native python object required by the application.

Records are similar to named tuples: the underlying storage mechanism is a tuple, and the fields are descriptors that provide named access to the tuple items. They are superior to named tuples since they enable the data model designer to specify types and constraints that must be satisfied by the data, and automate the conversion process to a large degree.

Inheritance among {Record} subclasses is interpreted as composition: the set of fields that define a record is built out of the descriptors declared both locally and by all of its ancestors. Descriptor composition is subject to name shadowing.

Records support {derivations}: fields whose value is computed using other record fields. Such fields are built automatically whenever a field declaration contains any sort of arithmetic on the right hand side.

Details of the current implementation:

• Storage for the record values is provided by {tuple}. This implies that indexed access using integers works as expected and does not require any special handling
• Named access is handled through the field descriptors. Supporting composition via inheritance complicates the implementation a bit, as the rank of a given field is not known until the class mro is traversed and shadowing is taken into account. Each {Record} subclass maintains its own map from descriptor instances to the integer rank in the corresponding underlying tuple.

pyre_name

pyre_localFields

pyre_fields

pyre_measures

pyre_derivations

pyre_columns