Contents > Developing ColdFusion MX Applications > Writing and Calling User-Defined Functions > Using UDFs effectively > Using the Request scope for static variables and constants

Using the Request scope for static variables and constants

This section describes how to partially break the rule described in the section Referencing caller variables. Here, the function defines variables in the Request scope. However, it is a specific solution to a specific issue, where the following circumstances exist:

• Your function initializes a large number of variables.
• The variables have either of the following characteristics:
  • They must be static: they are used only in the function, the function can change their values, and their values must persist from one invocation of the function to the next.
  • They are named constants; that is the variable value never changes.
• Your application page (and any custom tags) calls the function multiple times.
• You can assure that the variable names are used only by the function.

In these circumstances, you can improve efficiency and save processing time by defining your function's variables in the Request scope, rather than the Function scope. The function tests for the Request scope variables and initializes them if they do not exist. In subsequent calls, the variables exist and the function does not reset them.

The NumberAsString function, written by Ben Forta and available from www.cflib.org, takes advantage of this technique.

Contents > Developing ColdFusion MX Applications > Writing and Calling User-Defined Functions > Using UDFs effectively > Using the Request scope for static variables and constants

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