Delphi in a Nutshell

Name

Function Keyword

Syntax

function Name: Return type; Directives...
function Name(Parameters...): Return type; Directives...

type Name = function(Parameters...): Return type;
type Name = function(Parameters...): Return type of object;

Description

A function is a subroutine that returns a value. In the interface section of a unit, only the function header (its name, parameters, return type, and directives, but not the body) can appear. You can also define a functional type.

In the implementation section, you must provide a complete function definition for every function declared in the interface section. (See the external directive to learn how to define a function without providing a body.) You can omit the parameters in the implementation section if the function is not overloaded. If you provide the parameters, they must match exactly (including the parameter names) with the function header in the interface section.

A function’s implementation should not repeat the directives that appear first with the function header.

Tips and Tricks

• Although it seems like an additional maintenance burden to keep a copy of the header in the function’s implementation, it is a great benefit to the person who maintains the code. It is inconvenient to have to jump to the function’s declaration just to learn about the function’s parameters.

• You can declare multiple functions with the same name but different arguments by using the overload directive.

• A function can be declared in a class declaration, in ...