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32.19.1 Examining Text Properties

The simplest way to examine text properties is to ask for the value of a particular property of a particular character. For that, use get-text-property. Use text-properties-at to get the entire property list of a character. See Property Search, for functions to examine the properties of a number of characters at once.

These functions handle both strings and buffers. Keep in mind that positions in a string start from 0, whereas positions in a buffer start from 1.

— Function: get-text-property pos prop &optional object

This function returns the value of the prop property of the character after position pos in object (a buffer or string). The argument object is optional and defaults to the current buffer.

If there is no prop property strictly speaking, but the character has a property category that is a symbol, then get-text-property returns the prop property of that symbol.

— Function: get-char-property position prop &optional object

This function is like get-text-property, except that it checks overlays first and then text properties. See Overlays.

The argument object may be a string, a buffer, or a window. If it is a window, then the buffer displayed in that window is used for text properties and overlays, but only the overlays active for that window are considered. If object is a buffer, then overlays in that buffer are considered first, in order of decreasing priority, followed by the text properties. If object is a string, only text properties are considered, since strings never have overlays.

— Function: get-char-property-and-overlay position prop &optional object

This is like get-char-property, but gives extra information about the overlay that the property value comes from.

Its value is a cons cell whose car is the property value, the same value get-char-property would return with the same arguments. Its cdr is the overlay in which the property was found, or nil, if it was found as a text property or not found at all.

If position is at the end of object, both the car and the cdr of the value are nil.

— Variable: char-property-alias-alist

This variable holds an alist which maps property names to a list of alternative property names. If a character does not specify a direct value for a property, the alternative property names are consulted in order; the first non-nil value is used. This variable takes precedence over default-text-properties, and category properties take precedence over this variable.

— Function: text-properties-at position &optional object

This function returns the entire property list of the character at position in the string or buffer object. If object is nil, it defaults to the current buffer.

— Variable: default-text-properties

This variable holds a property list giving default values for text properties. Whenever a character does not specify a value for a property, neither directly, through a category symbol, or through char-property-alias-alist, the value stored in this list is used instead. Here is an example:

          (setq default-text-properties '(foo 69)
                char-property-alias-alist nil)
          ;; Make sure character 1 has no properties of its own.
          (set-text-properties 1 2 nil)
          ;; What we get, when we ask, is the default value.
          (get-text-property 1 'foo)
               ⇒ 69