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A property list (plist for short) is a list of paired elements, often stored in the property list cell of a symbol. Each of the pairs associates a property name (usually a symbol) with a property or value. Property lists are generally used to record information about a symbol, such as its documentation as a variable, the name of the file where it was defined, or perhaps even the grammatical class of the symbol (representing a word) in a language-understanding system.
Some objects which are not symbols also have property lists associated with them, and SXEmacs provides a full complement of functions for working with property lists. See Property Lists.
The property names and values in a property list can be any Lisp
objects, but the names are usually symbols. They are compared using
eq
. Here is an example of a property list, found on the symbol
progn
when the compiler is loaded:
(lisp-indent-function 0 byte-compile byte-compile-progn)
Here lisp-indent-function
and byte-compile
are property
names, and the other two elements are the corresponding values.
• Plists and Alists: | Comparison of the advantages of property lists and association lists. | |
• Object Plists: | Functions to access objects’ property lists. | |
• Other Plists: | Accessing property lists stored elsewhere. |