GNU Info

(elisp)Variables

---

Next: Functions Prev: Control Structures Up: Top

---

Enter node , (file) or (file)node

Variables
*********

   A "variable" is a name used in a program to stand for a value.
Nearly all programming languages have variables of some sort.  In the
text of a Lisp program, variables are written using the syntax for
symbols.

   In Lisp, unlike most programming languages, programs are represented
primarily as Lisp objects and only secondarily as text.  The Lisp
objects used for variables are symbols: the symbol name is the variable
name, and the variable's value is stored in the value cell of the
symbol.  The use of a symbol as a variable is independent of its use as
a function name.  Note: Symbol Components.

   The Lisp objects that constitute a Lisp program determine the textual
form of the program--it is simply the read syntax for those Lisp
objects.  This is why, for example, a variable in a textual Lisp program
is written using the read syntax for the symbol that represents the
variable.

Global Variables

Variable values that exist permanently, everywhere.

Constant Variables

Certain "variables" have values that never change.

Local Variables

Variable values that exist only temporarily.

Void Variables

Symbols that lack values.

Defining Variables

A definition says a symbol is used as a variable.

Tips for Defining

Things you should think about when you

define a variable.

Accessing Variables

Examining values of variables whose names

are known only at run time.

Setting Variables

Storing new values in variables.

Variable Scoping

How Lisp chooses among local and global values.

Buffer-Local Variables

Variable values in effect only in one buffer.

Frame-Local Variables

Variable values in effect only in one frame.

Future Local Variables

New kinds of local values we might add some day.

File Local Variables

Handling local variable lists in files.