ml-write(2)

NAME

ml-write - Write message on message line

SYNOPSIS

0 ml-write
n ml-write "message"

DESCRIPTION

ml-write writes the argument "message" to the message line. If a positive numeric argument n is specified then the message is displayed with a n milliseconds uninterruptible delay allowing the user time to see the message.

The arguments to ml-write are defined as follows:

No argument


The default form, writes a message to the command line with no delay.

+ve


Displays the message on the message line and waits n milliseconds before proceeding with the next command.

0


the message argument is not required and the command clears the message line. This may be used to clear any previous message from the last command(s) in a script and is equivalent to the old MicroEmacs command ml-clear.

-ve


If negative, the value is negated and used as a bitwise flag whose bits are defined as follows:

1


If running in piped mode (see command-line option -p) the message is written to standard-out as per 4 below, otherwise it is written to the message line as normal. This allows the same macro code to run correctly in both environments.

2


If running in piped mode the message is written to standard-error as per 4 below, otherwise it is written to the message line as normal.

4


Force the message to be written to standard-out if bit 1 is also set, or standard-error otherwise.

8


When set the function will return an ABORT, typically halting the execution of the current macro.

16


When set the function waits for the user to press a key, this can be used to ensure the user will see the message.

NOTES

If the argument value is not -1, -2, -4 or -5 calls to ml-write are ignored in standard MicroEmacs piped mode (command-line option -p). They are printed to standard error when debug piped mode is used (command-line option -P, see me(1)), making the debugging and maintenance of macro based piped processing easier.

In previous releases the command ml-clear was used to clear the message line, this command was replaced by 0 ml-write in December 2004.

EXAMPLE

The following call displays a message on the message-line with a 2 second pause:

2000 ml-write "Hello World!" 

The following start-up(3) macro may be used to add a header and footer line to a file piped to standard in, writing the output to standard out.

define-macro start-up 
    find-buffer "*stdin*" 
    ml-write &spr "DEBUG: Read %d lines from stdin" $window-eline 
    ml-write &spr "DEBUG: About to write header" 
    -1 ml-write "<<<HEADER>>>" 
    ml-write &spr "DEBUG: About to write body" 
    0 save-buffer 
    ml-write &spr "DEBUG: About to write footer" 
    -1 ml-write "<<<FOOTER>>>" 
    -2 ml-write &spr "%d lines written to stdout" &add $window-eline 2 
    quick-exit 
!emacro 

To run this example save this macro in a new macro file (such as mlwrite_test.emf) and in a shell run:

cat input_file | me -n -p @mlwrite_test - > output_file 

Note the DEBUG lines will be printed if -P option is used. Also see example given for command-wait(2).

SEE ALSO

command-wait(2), create-callback(2), me(1).

Ref: ml-write(2) File: m2cmd145.2 Date: 2024/09/23

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