DevGuide Cells

Overview

Cells are grouped into a three-tiered heirarchy:

• category: A collection of packages that are grouped together for display purposes
• package: A collection of related commands.
• command: A specific operation in a cell.

Commands are managed by info.vizierdb.commands.Commands. Call Commands.register() to register a package and its associated commands (see the bottom of the Commands implementation for an example).

A specific command is identified by the 2-part identifier: package.command

Implementing Commands

Each command includes the info.vizierdb.commands.Command trait, and should implement the following methods:

• name: The user-facing name of the command
• parameters: A sequence of info.vizierdb.commands.Parameters that describes the arguments to the command.
• format: Generate a short string representation of the command that will be displayed in the notebook.
• title: Generate a shorter string representation of the command that will be displayed in the table of contents.
• process: Execute the command.
• predictProvenance: Currently unused. Return None.

format, title and process receive an info.vizierdb.commands.Arguments object that provides access to the values of the parameters specified by parameters.

process also receives an info.vizierdb.commands.ExecutionContext that describes the notebook state at the point of the cell. The context can be used to retrieve artifacts, create artifacts, or output messages.