presence

Whether a dummy argument must be supplied.

声明

语法

presence = Required | Optional

Values

Value	Meaning
Required	the argument must be present at every call.
Optional	the optional attribute: the argument may be absent.

返回值

None. An enumeration value is not evaluated.

描述

An absent actual argument is a call_arg whose value is nil, so a call always has as many arguments as the procedure has dummies and a backend never has to match them up itself.

也可以看看

Variable, call_arg, FunctionCall