def

Purpose

The word def is used to define a "method" , "property" or "variable". The definition of methods and variables can occur almost anywhere in the body of a program. The properties are declared in the main body of a class.

A property is, by default, a publicly accessible and modifiable value that is owned by a class

The language has many predefined methods. For example, the method Math.sqrt() enables it to calculate the square root of a number. Often though, it is useful to be able to define your own methods, as their use greatly enhances the readability and reliability of programs.

Also methods may have parameters passed to them. For example

def vat(g) {1.175 * g}

"g" is called a "formal parameter" for the method vat(). It tells the computer that one number is going to be "passed" to the method when the method is used - and inside the method we have decided to use the letter g to represent the variable.

The method is "called" or used like this - for example

print "VAT inclusive price "
print vat(p)

and in this case "p" is the "actual parameter" for the method vat(). Whatever value "p" has will be used inside the method wherever reference is made to the "formal parameter"

Examples

@Important def length
def finalDestination = 180
def vat(g) {1.175 * g}

Description

A keyword which may precede declaration of a user method or variable. Methods need not be defined before they are called. A method declared with def always produces a result.

Variables are declared before usage.

Syntax

{annotations} {modifiers} def propertyName
{annotations} {modifiers} def propertyName = expression
{annotations} {modifiers} def methodName({parameters}) {{statements}}

Associated keywords