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Almost all the messages displayed in the echo area are also recorded
in the `*Messages*' buffer so that the user can refer back to
them. This includes all the messages that are output with
message.
This variable specifies how many lines to keep in the `*Messages*' buffer. The value
tmeans there is no limit on how many lines to keep. The valuenildisables message logging entirely. Here's how to display a message and prevent it from being logged:(let (message-log-max) (message ...))
To make `*Messages*' more convenient for the user, the logging facility combines successive identical messages. It also combines successive related messages for the sake of two cases: question followed by answer, and a series of progress messages.
A “question followed by an answer” means two messages like the
ones produced by y-or-n-p: the first is `question',
and the second is `question...answer'. The first
message conveys no additional information beyond what's in the second,
so logging the second message discards the first from the log.
A “series of progress messages” means successive messages like
those produced by make-progress-reporter. They have the form
`base...how-far', where base is the same each
time, while how-far varies. Logging each message in the series
discards the previous one, provided they are consecutive.
The functions make-progress-reporter and y-or-n-p
don't have to do anything special to activate the message log
combination feature. It operates whenever two consecutive messages
are logged that share a common prefix ending in `...'.