Output Streams

These are the different types of output stream, for the functions which use them see section Output Functions.

file

Writes to the file object file. See section Files.

mark

Writes to the position pointed to by the marked mark, then advances the position of the mark.

buffer

Writes to buffer at the position of the cursor in that buffer, which is then advanced.

(buffer . position)

position in the buffer buffer. position is then moved over the written text.

(buffer . t)

Writes to the end of the buffer buffer.

function

The function function is called with one argument, either a string or a character. This should be used as the circumstances dictate. If the function returns a number it is the number of characters actually used, otherwise it is assumed that all the characters were successful.

process

Writes to the standard input of the process object process. If process isn't running an error is signalled. See section Processes.

t

Appends the character(s) to the end of the status line message.

nil

Write to the stream stored in the variable standard-output.

It is also possible to store the characters sent to an output stream in a string.

Function: make-string-output-stream

Returns an output stream. It accumulates the text sent to it for the benefit of the get-output-stream-string function.

Function: get-output-stream-string string-output-stream

Returns a string consisting of the text sent to the string-output-stream since the last call to get-output-stream-string (or since this stream was created by make-string-output-stream).

(setq stream (make-string-output-stream))
    => ("" . 0)
(prin1 keymap-path stream)
    => ("(lisp-mode-keymap global-keymap)" . 64)
(get-output-stream-string stream)
    => "(lisp-mode-keymap global-keymap)"

Variable: standard-output

This variable contains the output stream which is used when no other is specified (or when the given output stream is nil).

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