independent position in the casefile.
Casereaders may only move forward. They cannot move
- backward to arbitrary records or seek randomly. (In the
- future, the concept of a "casemark" will be introduced
- to allow a limited form of backward seek, but this has
- not yet been implemented.)
-
- Cloning casereaders is possible, but no one has had a
- need for it yet, so it is not implemented.
+ backward to arbitrary records or seek randomly.
+ Cloning casereaders is possible, but it is not yet
+ implemented.
Use casefile_get_reader() to create a casereader for
- use in phase 2. This also transitions from phase 2 to
- phase 3. Calling casefile_mode_reader() makes the same
+ use in phase 2. This also transitions from phase 1 to
+ phase 2. Calling casefile_mode_reader() makes the same
transition, without creating a casereader.
Use casereader_read(), casereader_read_xfer(), or
also read with casereaders in this phase, but the
ability to create new casereaders is curtailed.
- In this phase, casereaders could still be cloned, and
- casemarks could still be used to seek backward (given
- that we eventually implement these functionalities).
+ In this phase, casereaders could still be cloned (once
+ we eventually implement cloning).
To transition from phase 1 or 2 to phase 3 and create a
casereader, call casefile_get_destructive_reader().
more casereaders may be created with
casefile_get_reader() or
casefile_get_destructive_reader(). (If cloning of
- casereaders or casemarks were implemented, they would
- still be possible.)
+ casereaders were implemented, it would still be
+ possible.)
The purpose of the limitations applied to casereaders
in phase 3 is to allow in-memory casefiles to fully