I usually want to know if the argument was passed, not if the argument
is the default value. With a default value, that value necessarily
has to be a legal value for the argument. Therefore there's no way to
tell if it was omitted or if the default value was explicitly passed.
Take this function for example:
<cffunction name="test">
<cfargument name="myArg" type="string" required="false" default="" />
<cfif myArg EQ "">
...
</cfif>
</cffunction>
The conditional will execute for both of these invocations:
test();
test("");
However, if I use this function:
<cffunction name="test">
<cfargument name="myArg" type="string" required="false" />
<cfif NOT structKeyExists(arguments, myArg)>
...
</cfif>
</cffunction>
The conditional will only execute for the former (where the argument
wasn't passed), and it'll treat "" just like it would treat any other
passed value.
cheers,
barneyb
On Wed, 1 Dec 2004 10:27:54 -0500, Sparrow-Hood, Walter
<[EMAIL PROTECTED]> wrote:
> Barney,
> I'm curious - why do you prefer structKeyExists() vs. setting
> default values?
>
> Walt
>
>
>
> -----Original Message-----
> From: Barney Boisvert [mailto:[EMAIL PROTECTED]
> Sent: Tuesday, November 30, 2004 6:26 PM
> To: CF-Talk
> Subject: Re: CFC required arguments
>
> If you use positional parameters, only parameters at the end can be
> left off. However, you can use named parameters without using
> CFINVOKE:
>
> <cfset o.method(name=url.name, age=url.age, ...) />
>
> I generally prefer to not specify a default for my option arguments,
> and then use structKeyExists() against the 'arguments' struct to check
> if they were passed. Since we don't have method overloading in CF,
> optional parameters (and their associated conditionals) are a
> necessary evil.
>
> cheers,
> barneyb
--
Barney Boisvert
[EMAIL PROTECTED]
360.319.6145
http://www.barneyb.com/blog/
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