
242
Chapter 11: Building and Using ColdFusion Components
Establishing a descriptive naming convention is a good practice, especially if the components will
be installed as part of a packaged application.
CFC variables
This section describes how CFCs use variables and interact with ColdFusion scopes.
Note:
Components also have a Super keyword that is sometimes called a scope. For information on
the Super keyword, see
“Using the Super keyword” on page 246
.
The This scope
The This scope is available within the CFC and is shared by all CFC methods. It is also available
in the page that instantiates the CFC and all CFML pages included by the CFC.
Note:
If you use component inheritance, you cannot use the This scope in the base (parent)
component, only in the component that extends it. For more information, see
“Using component
inheritance” on page 245
.
Inside the CFC, you define and access This scope variables by using the prefix
This
, as in the
following line:
<cfset This.color="green">
In the calling page, you can define and access CFC This scope variables by using the CFC
instance name as the prefix. For example, if you create a CFC instance named
car
and within the
car CFC, specify
<cfset "This.color=green">
, then a ColdFusion page that instantiates the
CFC could refer to the component’s color property as
#car.color#
.
Variable values in the This scope last as long as the CFC instance exists, and therefore can persist
between calls to methods of a CFC instance.
Note:
The This scope identifier corresponds to the This keyword of JavaScript and ActionScript.
CFCs do not follow the Java class model, and the This keyword behaves differently in ColdFusion
MX than in Java.
The Variables scope
The Variables scope in a CFC is private to the CFC. It includes variables defined in the CFC
body (initialization or constructor code) and in the CFC methods. Variables scope variables that
are set in the CFC cannot be seen by pages that invoke the CFC.
The CFC Variables scope does not include any Variables scope variables that are declared or
available in the page that instantiates or invokes the CFC. However, you can make the Variables
scope of the page that invokes a CFC accessible to the CFC by passing Variables as an argument
to the CFC method.
You set a Variables scope variable by assigning a value to a name that has the Variables prefix or no
prefix.
Values in the Variables scope last as long as the CFC instance exists, and therefore can last
between calls to CFC instance methods.
The Variables scope is available to included pages, and Variables scope variables that are declared
in the included page are available in the component page.
Содержание COLDFUSION MX 61-DEVELOPING COLDFUSION MX
Страница 1: ...Developing ColdFusion MX Applications...
Страница 22: ...22 Contents...
Страница 38: ......
Страница 52: ...52 Chapter 2 Elements of CFML...
Страница 162: ......
Страница 218: ...218 Chapter 10 Writing and Calling User Defined Functions...
Страница 250: ...250 Chapter 11 Building and Using ColdFusion Components...
Страница 264: ...264 Chapter 12 Building Custom CFXAPI Tags...
Страница 266: ......
Страница 314: ...314 Chapter 14 Handling Errors...
Страница 344: ...344 Chapter 15 Using Persistent Data and Locking...
Страница 349: ...About user security 349...
Страница 357: ...Security scenarios 357...
Страница 370: ...370 Chapter 16 Securing Applications...
Страница 388: ...388 Chapter 17 Developing Globalized Applications...
Страница 408: ...408 Chapter 18 Debugging and Troubleshooting Applications...
Страница 410: ......
Страница 426: ...426 Chapter 19 Introduction to Databases and SQL...
Страница 476: ...476 Chapter 22 Using Query of Queries...
Страница 534: ...534 Chapter 24 Building a Search Interface...
Страница 556: ...556 Chapter 25 Using Verity Search Expressions...
Страница 558: ......
Страница 582: ...582 Chapter 26 Retrieving and Formatting Data...
Страница 668: ......
Страница 734: ...734 Chapter 32 Using Web Services...
Страница 760: ...760 Chapter 33 Integrating J2EE and Java Elements in CFML Applications...
Страница 786: ...786 Chapter 34 Integrating COM and CORBA Objects in CFML Applications...
Страница 788: ......
Страница 806: ...806 Chapter 35 Sending and Receiving E Mail...