Filtering Undeclared Arguments
One thing I have wanted to do in ColdFusion for some time is to limit the arguments scope in a function to arguments I have declared with cfargument. That feature doesn't exist, but I made the next best thing.
Here is the syntax that I want:
<cfargument name="a">
<cfargument name="b">
<cfargument name="c">
<cfdump var="#arguments#">
</cffunction>
Then I could call the function like this:
And get the following dump:
In reality, I get this:
So, I made a UDF to do the next best thing:
<cfargument name="a">
<cfargument name="b">
<cfargument name="c">
<cfset filterArguments(testMethod,arguments)>
<cfdump var="#arguments#">
</cffunction>
<cfset testMethod(a=1,b=2,c=3,d=4,e=5,f=6,g=7)>
Without the limitargs attribute:
<cfargument name="a">
<cfargument name="b">
<cfargument name="c">
<cfset filterArguments(testMethod,arguments)>
<cfdump var="#arguments#">
</cffunction>
<cfset testMethod(a=1,b=2,c=3,d=4,e=5,f=6,g=7)>
Note that the code takes the function itself (not the name of the function) as the first argument. If you didn't know, you can actually pass a function around in ColdFusion (and even execute the passed function).
Here is the filterArguments UDF:
<cfargument name="method" type="any">
<cfargument name="args" type="any">
<cfset var sMethod = getMetaData(arguments.method)>
<cfset var arglist = "">
<cfset var ii = "">
<!--- Only take action if the function has limitargs attribute set to true --->
<cfif StructKeyExists(sMethod,"limitargs") AND sMethod.limitargs IS true>
<!--- Get a list of arguments --->
<cfif ArrayLen(sMethod.Parameters)>
<cfloop index="ii" from="1" to="#ArrayLen(sMethod.Parameters)#">
<cfset arglist = ListAppend(arglist,sMethod.Parameters[ii].name)>
</cfloop>
</cfif>
<!--- Ditch any argument not in the list --->
<cfloop collection="#arguments.args#" item="ii">
<cfif NOT ListFindNoCase(arglist,ii)>
<cfset StructDelete(arguments.args,ii)>
</cfif>
</cfloop>
</cfif>
<!--- Just in case it is called as arguments=filterArguments() --->
<cfreturn arguments>
</cffunction>
The first thing this function does is get the meta data of the function passed to it:
Then it checks the value of the limitargs attribute:
I used "IS true" so that it will use an empty string as false, but accept true or 1 or yes as true.
After that, I loop through the arguments in the meta data to build a list of arguments and remove any arguments that aren't in the list.
As a safety measure, I return the arguments. This is just in case the function is called as arguments=filterArguments(method,arguments). I didn't want it to mess up the arguments scope in that case.
I would still like the feature to be native, but I think this meets my needs nicely until then.
