Nesting custom tags
187
Nested custom tags operate through three modes of processing, which are exposed to the base tags
through the variable
thisTag.ExecutionMode
:
•
The
start
mode, in which the base tag is processed for the first time.
•
The
inactive
mode, in which sub tags and other code contained within the base tag are
processed. No processing occurs in the base tag during this phase.
•
The
end
mode, in which the base tag is processed a second time. The end mode occurs when
ColdFusion reaches the custom tag’s end tag.
Passing data between nested custom tags
A key custom tag feature is for collaborating custom tags to exchange complex data without user
intervention, while encapsulating each tag’s implementation so that others cannot see it.
When you decide to you use nested tags, you must address the following issues:
•
What data should be accessible?
•
Which tags can communicate to which tags?
•
How are the source and targets of the data exchange identified?
•
What CFML mechanism is used for the data exchange?
What data is accessible?
To enable developers to obtain maximum productivity in an environment with few restrictions,
CFML custom tags can expose all their data to collaborating tags.
When you develop custom tags, you should document all variables that collaborating tags can
access and/or modify. When your custom tags collaborate with other custom tags, you should
make sure that they do not modify any undocumented data.
To preserve encapsulation, put all tag data access and modification operations into custom tags.
For example, rather than documenting that the variable MyQueryResults in a tag's
implementation holds a query result and expecting users to manipulate MyQueryResults directly,
create a nested custom tag that manipulates MyQueryResult. This protects the users of the
custom tag from changes in the tag's implementation.
Variable scopes and special variables
Use the Request scope for variables in nested tags. The Request scope
is available to the base page,
all pages it includes, all custom tag pages it calls, and all custom tag pages called by the included
pages and custom tag pages. Collaborating custom tags that are not nested in a single tag can
exchange data using the request structure. The Request scope is represented as a structure named
Request
.
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...