Because the value is set by using <cfparam> rather than <cfset>, you can safely add this snippet into each circuit s FBX_Settings.cfm file.

Fuses, as we discuss in 37 are the individual code files used by the core Fusebox files to perform actions; they re the workhorses of Fusebox. Indeed, fuses are little different from code files used by other architectures with two differences: Fuses rely on XFAs, and each fuse begins with an XML documentation system known as Fusedoc. You know that you should document our code, having heard this mantra from your earliest days as coders. Although everyone is quick to point out that you should document your code, however, almost no one has any specific advice on how to achieve this. Such nonprescriptive advice is of little practical value, and programmer comments often tilt between the trivial and the oblique. Fusedoc tells you exactly how to document your code. The fundamental rule of a Fusedoc is that a Fusedoc is responsible for telling a coder all the information necessary to write the code for the fuse. A DTD (Document Type Definition) is available at www.halhelms.com. (If you use ColdFusion Studio as your code editor, you can find tag editors at www.fusebox.org that make writing Fusedocs much easier.) Open a fuse, and the first thing that you see is the Fusedoc. It s an XML document that sits atop the page. Listing 38-6 shows the entire code for a fuse used to validate a user login.

<!--<fusedoc fuse= act_Validate.cfm language= ColdFusion version= 2.0 > <responsibilities> I determine the next fuseaction based on whether the user was validated or not. If ValidatedUser returns any rows, I return to the FB with XFA.success; else XFA.failure. </responsibilities> <properties> <history author= hal helms date= 4 July 2002 role= Architect /> <property name= complexity value= 1 /> </properties> <io> <in> <string name= self /> <recordset name= ValidatedUser > <string name= userID /> <string name= firstName /> <string name= lastName /> <number name= userPermissions precision= integer /> </recordset> <structure name= XFA > <string name= success /> <string name= failure /> </structure> </in> <out> <structure name= CurrentUser scope= session optional= true oncondition= on XFA.success > <string name= userID passthrough= ValidatedUser.userID /> <string name= firstName passthrough= ValidatedUser.firstName /> <string name= lastName passthrough= ValidatedUser.lastName /> <number name= userPermissions

Listing 38-6 (continued)

precision= integer passthrough= ValidatedUser.userPermissions /> </structure> <string name= fuseaction scope= formorurl /> </out> </io> </fusedoc> ---> <cfif ValidatedUser.recordCount> <cfset str = StructNew()> <cfset str.userID = ValidatedUser.userID> <cfset str.firstName = ValidatedUser.firstName> <cfset str.lastName = ValidatedUser.lastName> <cfset str.userPermissions = ValidatedUser.userPermissions> <cflock scope= session timeout= 5 type= exclusive > <cfset Session.CurrentUser = Duplicate( str )> </cflock> <cflocation url= index.cfm fuseaction=#XFA.success# > <cfelse> <cflocation url= index.cfm fuseaction=#XFA.failure# > </cfif>

To give you a sense of how Fusedocs work, though, the following steps dissect the Fusedoc for the fuse shown in Listing 38-6. 1. A Fusedoc is wrapped in ColdFusion comments so that it is stripped out prior to being sent to the browser. The information contained in the Fusedoc is for the coder, not for the end user, and exposing it could raise security concerns. 2. All XML documents have a single root element. In Fusedoc, the root element is <fusedoc>. 3. You have three subelements to <fusedoc>. They are <responsibilities>, <properties>, and <io> (for input/output). The only mandatory element is <responsibilities>. 4. The <responsibilities> element indicates to the coder the fuse s purpose why does the fuse exist It is written in the first person and should be stated as plainly as possible without duplicating information better left to the <io> section. In this example, the coder is told what the fuse is to do: Determine the next fuseaction to be taken.