Gamma™ : Version 6.4
	Core Functions

`defvar`

defvar — defines a global variable with an initial value.

Syntax

defvar (!symbol, value, constant_p?)

Arguments

symbol: A variable name which has not yet been assigned a value.
value: Any s_exp.
constant_p: If non-nil, the symbol will be assigned as a constant.

Returns

The value of the symbol.

Description

This function defines a global variable with an initial value. If the constant_p argument is present and non-nil, then the symbol becomes a constant, and any attempt to set its value in any scope will fail. If the symbol already has a value and constant_p is non-nil or absent, then defvar will return immediately with the current value of the symbol. If constant_p is non-nil and the symbol already has a value, then an error is generated.

The intent of defvar is to provide a value for a symbol only if that symbol has not yet been defined. This allows a Gamma or Lisp file to contain default symbol values which may be overridden before the file is loaded.

Example

Gamma> defvar(a,7,t);
7
Gamma> a;
7
Gamma> a = 5;
Assignment to constant symbol: a
debug 1>

Gamma> b = 9;
9
Gamma> defvar(b,10);
9
Gamma> b;
9
Gamma>


defmethod		destroy

defvar