VariableReadCallback¶

Canonical path: o6.server.VariableReadCallback

VariableReadCallback ¶

Bases: Protocol

The shape of a Variable value-read implementation.

Registered with o6.read or Server.addVariable. The callback runs on the server's event loop, so it must not block.

__call__(node, *, range, session, includeSourceTimestamp)

Produce the value of the Variable.

Parameters:

Name	Type	Description	Default
`node`	`VariableNode`	The Variable being read.	required
`range`	`tuple[slice, ...] \| None`	The requested index range, or `None` for the whole value.	required
`session`	`Session \| None`	The reading session, or `None` for an internal read.	required
`includeSourceTimestamp`	`bool`	Whether the caller wants a SourceTimestamp.	required

Returns:

Type	Description
`tuple[Any, ...]`	A tuple of the StatusCode and the value.