Design of lsst.pex.config¶
This page is a collection of notes describing the design of lsst.pex.config and the pex_config package in general.
Design goals¶
- Enable configuration of plug-in algorithms provided at runtime.
- Allow setting of one
Field
to affect the values and the validation of others. - Collocate the
Config
definition with the code using theConfig
. - Provide a “Pythonic” interface.
- Record the file and line of
Field
instance definitions and all changes toField
instances, including setting default values. - Set defaults before overriding with user-specified values.
- Support parameters with no (nonexistent) values, including overriding existing default values.
- Enable closely-related
Config
objects to be represented efficiently, with a minimum of duplication. - Have all user-modifiable
Config
instances be part of a hierarchical tree. - Validate the contents of
Field
instances as soon as possible. - Be able to “freeze” a
Config
instance to make it read-only. - Be able to persist a
Config
instance to a file and restore it identically. - Allow C++ control objects to be created from
Config
objects, with documentation and validation specified exactly once. - Support lists of parameter values.