Ask Ben: Get Arguments For ColdFusion User Defined Functions
Posted December 1, 2008 at 2:56 PM by Ben Nadel
I know that with a CFC you can view the cfc and it will give you a listing of the methods, arguments, etc. But I have single page that has a ton of different UDF's within it. I can do a cfdump of the variables struct, which will then give me a great look at all the UDF's. Is there an way to do:
<cfloop collection="#variables#" item="key">
#lcase(key)#
</cfloop>
and have it give me the arguments that are required? I am working on some documentation, so that would make my life 100x easier.
The key to this problem is ColdFusion's GetMetaData() method. This method allows us to get data about many objects in ColdFusion, including method arguments. To use this, all we need to do is modify your example code such that it picks out the methods in the page and then gathers their meta data:
- <!---
- Loop over all the keys in our VARIABLES scope. This could be
- *any* scope, but for this test, we are using the local scope
- of my *test* page.
- --->
- <cfloop
- item="strKey"
- collection="#VARIABLES#">
-
- <!---
- Check to see if this value is a user defined function.
- If so, then we can inspect it.
- --->
- <cfif IsCustomFunction( VARIABLES[ strKey ] )>
-
-
- <!--- Get a pointer to the method. --->
- <cfset fnMethod = VARIABLES[ strKey ] />
-
- <!--- Get the meta data of the method. --->
- <cfset objMetaData = GetMetaData( fnMethod ) />
-
- <!--- Dump out the meta data. --->
- <cfdump
- var="#objMetaData#"
- label="Method: #strKey#"
- />
-
-
- </cfif>
-
- </cfloop>
Because the VARIABLES scope will have a ton of information in it, we utilize ColdFusion's IsCustomFunction() method to make sure that we select only the user defined functions. Once we know that the data key in question is a method, we get a pointer to the function. Since user defined methods (UDFs) in ColdFusion are first-class objects, this pointer to the function now acts in lieu of the original function. We then get the meta data on this function and dump it out. On my test page, this creates the following output:
| | | | | |
| |  | | ||
| | | |
As you can see, not only does this give us all the information defined in the CFFunction tag, it also gives us an ordered array of the method arguments. Now, my functions are well documented in their tags, so this output is robust; but, realize that if you leave data out of a tag (or use CFScript function definitions), then much of this data will not come through in the GetMetaData() function as it cannot be determined.
Reader Comments
I'm not certain, but I think part of the plan with the CF9 beta has been to allow us to define data types (and possibly default / required values) when declaring functions with cfscript. If that turns out to be true then that should hopefully make that extra metadata accessible this way as well, but of course, not with current versions. :)
@Ike,
I believe you are correct - but I'll believe it when I see it :)
In Addition to getMetadata() - you also have getComponentMetadata() - http://livedocs.adobe.com/coldfusion/8/htmldocs/functions_e-g_33.html
Kudos to Ray Camden for pointing it out elsewhere.
Thanks so much, Ben.
@Todd,
I could definitely see that as useful when you are creating documentation since you do not need an actual instance of the object in order to get the meta data.
@Brandon,
My pleasure man. I hope this helped a bit.
