NAME
    saveval - enable or disable saving of values

SYNOPSIS
    saveval(arg)

TYPES
    arg		any

    return	null value

DESCRIPTION
    When evaluation of a line of statements at top level starts, a
    "saved value" for that line is assigned the null value.  When saving
    is enabled (the initial state) and a statement being evaluated is an
    expression or a return statement, the value returned by that expression
    or statement replaces the current saved value; on completion of
    evaluation of the line, the saved value, if it is not null, updates
    the "oldvalue".

    This saving of values is enabled or disabled by calling saveval(arg)
    with an argument arg that tests as nonzero or zero,

    Whether saving is enabled or disabled does not affect the operation of
    eval(str).

EXAMPLE
    > saveval(1);
    > a = 27;
    .
	    27
    > saveval(0);
    > a = 45
    .
	    27
    > saveval(1);
    > a = 63
    .
	    63

LIMITS
    none

LIBRARY
    none

SEE ALSO
    oldvalue, eval