packet (script)

Description

In Regina 6.0.1 and earlier, the packet element was used to store every packet in the entire packet tree that makes up a Regina data file. This page describes how the packet element was structured when storing a script packet. Since Regina 7.0, each packet type has its own XML element; in particular, script packets are now stored using the script element.

A script packet stores a Python script offering direct low-level access to the Regina calculation engine.

A script may contain variables representing other packets in the same packet tree; these are described by the child var elements.

The way the Python code is stored has changed over time:

Both storage methods are still recognised by Regina when reading old second-generation data files.

If you are writing a second-generation data file that must be read by very old versions of Regina (dating back to Regina 4.95), then you may write the script twice: first as a series of line elements, and then again as a single text element. However, the line elements must come first, since when Regina reads a file it will append each line to the script, whereas if it sees a text element it will replace the script entirely. Therefore, if the line elements appear after the text element, Regina will effectively build two copies of the script end-on-end.

The roles played by the child tag and packet elements are described in the general packet element documentation.