passing variables to cfc method

[daveioi]

Hi

I've just written my first couple of cfcs, and passed the variables to the methods using the cfinvoke attributes. This doesn't seem to require the cfargument (ie the method works for me and I haven't used cfargument).

So I must admit that I'm a bit confused about what the point of the cfargument tag is, exactly? What will go wrong if I don't use it?

Many thanks

Dave S

[dongzky]

Methods can either contain cfargument or not. They can be required or not required. Since your method doesn't have cfarguments, then your method does not require any variable inputs(cfarguments) which will work fine.

You only need cfargument if your method needs to accept variables(required or not required) and process those variables. There are lot of uses in putting cfarguments and a lot of reasons depending on the programmer and process/application you are trying to achieve. Example, if you are trying to create a cfc for arithmetic and inside that cfc is a method that adds numbers, how will your method know what numbers to add if you don't pass variable inputs(that will be received by cfarguments)? But if your process doesn't require to process any input variables, then there is no need for cfarguments, and definitely no need for passing variables to your method(in cfc) which does not even receive one. Take note that methods are actually functions, and functions can either take arguments or not. This concept is common to all scripting and programming languages.

[daveioi]

Hi
thanks for that answer. But what seems to be the case to me is that variables can be processed in a method without having cfargument to accept them - I think I must be misunderstanding something somewhere.

Eg in my "beginners" component I have the following on a cfm template and on a cfc, the first passes a variable to the second but I haven't used cfargument:

[Hydrowizard]

all very good questions, I'm interested to hear what the gurus say as well on that one daveioi

[Newsgroup_User]

> So I must admit that I'm a bit confused about what the point of the cfargument
> tag

Have you read the docs for <cfargument>? That's always a good place to
start when trying to find out what something does.

http://livedocs.adobe.com/coldfusion/8/Tags_a-b_6.html

In short, <cfargument> has these benefits:
- enables type validation on arguments;
- enables requiredness validation on arguments;
- enables the provision of default values for optional arguments;
- enables the creation of API documentation for your CFCs (and, indeed,
code self-documentation);
- enables the definition of an interface for overridden CFC definitions;
- enables the definition of web services (or at least allows one to defined
web services that take arguments, anyhow).

--
Adam

[daveioi]

Thank you for that, it answers my question - ie it's necessary in some cirumstances, very useful in others but perhaps not necessary in yet other circumstances.

Dave

[Dinghus]

Actually good programming practice says you will use it all the time to prevent unwanted code from comiing in disguised as your form field.

Ever hear of sql injection attacks? If you are not validating input data you are open to such attacks.

ALWAYS know what is coming in to your programs. cfarguments at least verify that it is the proper type.