:focus

Arguments: &optional process

With no arguments, print the process on which the listener process is focused. Otherwise, focus on process, arresting it for debugging if :debugging is not already on process's list of arrest reasons. Focus on the listener process if the argument is :listener. Note that the listener process is not arrested.

:focus keeps a stack of processes on which the user has focused. When the current focus is moved from a process by using the command :unarrest, this stack is used to determine which process will become the focused process. The listener will become the focused process if no other processes are on the stack.

The process argument can be:

• A string, which is processed as described below.
• A symbol, which is evaluated to produce a process object, a string, an integer, or a symbol. If the value is a symbol, its print name is used as if that were the string provided.
• A list, which is evaluated to produce a process object, a string, an integer, or a symbol. If the value is a symbol, its print name is used as if that were the string provided.
• An integer, which designated the process whose process-sequence value is that integer.

Strings are compared with process names. All processes whose names exactly match the string are considered matches. If no process name exactly matches, then all processes whose names contain the string as a substring are considered matches. (For example, if there are processes with names "Listener 1" and "Initial Lisp Listener", both match the string "ener".) Since only one argument process is allowed, multiple matches cause the command to fail with a diagnostic.

Strings which match no process also cause the command to fail with a diagnostic.

The minimal abbreviation of :focus is :fo.

See top-level.htm for more information on top-level commands. See also multiprocessing.htm.

Copyright (c) 1998-2022, Franz Inc. Lafayette, CA., USA. All rights reserved.
This page has had moderate revisions compared to the 10.0 page.
Created 2019.8.20.