[P] Programming

4.2 Default initialization
class — Class programming 31
When an instance of a class is created, the member variables are filled in as follows:
4.3 Specifying initialization
double . (missing value)
string ""
classname as specified by class definition
array empty, an array with no elements yet defined
You may specify in classname.class the initial values for member variables. To do this, you
type an equal sign after the identifier, and then you type the initial value. For example,
begin todolist.class
version 11
class todolist {
double n = 0
string name = "nobody"
array list = {"show second syntax", "mark as done"}
actions x = .actions.new arguments
}
The initialization rules are as follows:
end todolist.class
double membervarname = . . .
After the equal sign, you may type any number or expression. To initialize the member
variable with a missing value (., .a, .b, . . . , .z), you must enclose the missing value in
parentheses. Examples include
double n = 0
double a = (.)
double b = (.b)
double z = (2+3)/sqrt(5)
Alternatively, after the equal sign, you may specify the identifier of a member variable to
be copied or program to be run as long as the member variable is a double or the program
returns a double. If a member program is specified that requires arguments, they must be
specified following the identifier. Examples include
double n = .clearcount
double a = .gammavalue 4 5 2
double b = .color.cvalue, color(green)
The identifiers are interpreted in terms of the global context, not the class context being
defined. Thus .clearcount, .gammavalue, and .color.cvalue must exist in the global
context.
string membervarname = . . .
After the equal sign, you type the initial value for the member variable enclosed in quotes,
which may be either simple (" and ") or compound (‘" and "’). Examples include
string name = "nobody"
string s = ‘"quotes "inside" strings"’
string a = ""