Classes (Components)

In lucee, classes are called Components and have the file extension .cfc. Lucee supports many OOP class features like interfaces, inheritance, & public and private methods. They are called Components because Lucee classes are also used for implementing framework features like ORM & REST. To see these advanced usages of Components, refer to the Developing Applications section. The rest of this section will discuss standard OOP features.

Component Definition

Implicit Constructor

Any code within the body of the component before any functions are defined is known as the "implicit constructor". This code will be executed on each instantiation of the CFC no matter the instantiation method. This can be used for code which must always be run. This was the original constructor strategy for Lucee, but most applications today use the Default Constructor described below.

Default Constructor

In lucee, components may have a default constructor method by providing a function called init. There can only be one constructor and Lucee does not support method overloading

Methods

Components can define additional methods and they can have the following access levels:

Public - Accessible to all callers
Private - Accessible to only callers within this class
Package - Accessible to other Components in a package
Remote - Accessible to remote callers via web services, REST or invoking components from HTTP

To define additional methods

The above declaration represents the following

  [access] [return type] function [function name](){

  }

See Types for a list of Types that functions can be annotated with.

Method Arguments

In Lucee, method arguments can be optionally typed, optionally required, and have default values

Typed Arguments

Required Arguments

Required & Typed Arguments

Default Arguments

Instantiation

New Operator

Using the New Operator, Lucee will instantiate the class and call the default constructor (if it exists)

CreateObject()

The createObject function is provided to instantiate Components, but also Java, Com and Webservice Objects. It also allows instantiating components with dynamic variable names.

Component Lookup Rules

When instantiating components they are found in the following ways

Any Components that are in the same directory as the script instantiating the component
Any Components imported into the script using the import keyword
Any Components pathed to using dotted notation, starting from the webroot
Any Components pathed to using dotted notation, that can be found from a mapping in Application.cfc

For Example, consider the following structure

/MyWebApp
- /components
  - subComponent.cfc
- Application.cfc
- rootComponent.cfc
- index.cfm

We're going to instantiate subComponent.cfc from within rootComponent.cfc and index.cfm runs our application.

rootComponent.cfc: This will find the subComponent because it can be pathed from the webroot (/components/subComponent)

Components can also be imported:

Notice that the import pathed from the webroot, but then we instantiated the component directly.

If Components are not accessible from the webroot and are stored elsewhere in on the file system system or outside of the webroot for security (a best practice), then they need an Application Mapping to access them.

Classes