31.4 Inserting Text

Insertion means adding new text to a buffer. The inserted text goes at point—between the character before point and the character after point. Some insertion functions leave point before the inserted text, while other functions leave it after. We call the former insertion after point and the latter insertion before point.

Insertion moves markers located at positions after the insertion point, so that they stay with the surrounding text (see Markers). When a marker points at the place of insertion, insertion may or may not relocate the marker, depending on the marker’s insertion type (see Marker Insertion Types). Certain special functions such as insert-before-markers relocate all such markers to point after the inserted text, regardless of the markers’ insertion type.

Insertion functions signal an error if the current buffer is read-only (see Read Only Buffers) or if they insert within read-only text (see Special Properties).

These functions copy text characters from strings and buffers along with their properties. The inserted characters have exactly the same properties as the characters they were copied from. By contrast, characters specified as separate arguments, not part of a string or buffer, inherit their text properties from the neighboring text.

The insertion functions convert text from unibyte to multibyte in order to insert in a multibyte buffer, and vice versa—if the text comes from a string or from a buffer. However, they do not convert unibyte character codes 128 through 255 to multibyte characters, not even if the current buffer is a multibyte buffer. See Converting Representations.

Function: insert &rest args

This function inserts the strings and/or characters args into the current buffer, at point, moving point forward. In other words, it inserts the text before point. An error is signaled unless all args are either strings or characters. The value is nil.

Function: insert-before-markers &rest args

This function inserts the strings and/or characters args into the current buffer, at point, moving point forward. An error is signaled unless all args are either strings or characters. The value is nil.

This function is unlike the other insertion functions in that it relocates markers initially pointing at the insertion point, to point after the inserted text. If an overlay begins at the insertion point, the inserted text falls outside the overlay; if a nonempty overlay ends at the insertion point, the inserted text falls inside that overlay.

Command: insert-char character &optional count inherit

This command inserts count instances of character into the current buffer before point. The argument count must be an integer, and character must be a character.

If called interactively, this command prompts for character using its Unicode name or its code point. See Inserting Text in The GNU Emacs Manual.

This function does not convert unibyte character codes 128 through 255 to multibyte characters, not even if the current buffer is a multibyte buffer. See Converting Representations.

If inherit is non-nil, the inserted characters inherit sticky text properties from the two characters before and after the insertion point. See Sticky Properties.

Function: insert-buffer-substring from-buffer-or-name &optional start end

This function inserts a portion of buffer from-buffer-or-name into the current buffer before point. The text inserted is the region between start (inclusive) and end (exclusive). (These arguments default to the beginning and end of the accessible portion of that buffer.) This function returns nil.

In this example, the form is executed with buffer ‘bar’ as the current buffer. We assume that buffer ‘bar’ is initially empty.

---------- Buffer: foo ----------
We hold these truths to be self-evident, that all
---------- Buffer: foo ----------

(insert-buffer-substring "foo" 1 20)
     ⇒ nil

---------- Buffer: bar ----------
We hold these truth∗
---------- Buffer: bar ----------

Function: insert-buffer-substring-no-properties from-buffer-or-name &optional start end

This is like insert-buffer-substring except that it does not copy any text properties.

See Sticky Properties, for other insertion functions that inherit text properties from the nearby text in addition to inserting it. Whitespace inserted by indentation functions also inherits text properties.