Since you asked, a few other thoughts:
1) A lot of people have taken to creating an "init" method in their CFCs --
this is parallel to the way CF handles calling the constructor of java
objects, so it makes code consistent. The init method can then take
whatever arguments you want. Personally, I like to return "this" in my init
methods, which lets me do:
foo = createObject("component","foo").init(arg,arg2);
(as an aside, that is the only time I ever use "this" in my CFCs because I
hate having "private" data in the "public" scope)
I always put an init method in my components, even if it does nothing at
all -- that way I just know that I should ALWAYS run init() when
instantiating -- I find that easier and more consistent, and it prevents me
from having to worry about whether or not a given component needs to have
init() run (and makes it easier to add an init method later without needing
to change a lot of code).
2) Another common practice is to create a "virtual scope" in the unnamed
scope. I call mine "instance" (I've also seen it called "private" and
"my"). Basically, I just do this in the "pseudo-constructor":
<cfset instance = structNew()>
(I sometimes use CFPARAM, which is better if you are extending another
component -- but, that's a nuance)
I then use "instance." as the prefix for all instance variables -- this
makes code more readable, IMO, and prevents any name collisions with
arguments or local (to a method) variables. Thus, I can do things like:
<cffunction name="setFoo"....>
<cfargument name="foo">
<cfset instance.foo = arguments.foo>
</cffunction>
Some have told me I should never use the same names for instance vars and
arguments like that, but I find it to be nice to refer to something by the
same name in different scopes.
I've also seen some people use an "_" to prefix all "private" instance
variables.
(I am using quotes around "private" because in CFCs data is never really
private at all -- more like "protected" in java, and not even actually like
that).
3) Be sure to put OUTPUT="false" in your CFFUNCTION and CFCOMPONENT tags --
otherwise you get white space in your calling page.
4) This is worth repeating even though it has been covered ad nauseum on
this list: ALWAYS ALWAYS ALWAYS use the "var" keyword for ALL local (to a
method) variables. This includes "i" in loops, names of queries, etc. --
you will never regret doing it and could end up pulling your hair out if you
don't.
> -----Original Message-----
> From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]
> Behalf Of cf_nut
> Sent: Friday, July 25, 2003 9:42 AM
> To: [EMAIL PROTECTED]
> Subject: Re: [CFCDev] CFC basics
>
>
> --- "Paul Johnston" <[EMAIL PROTECTED]> wrote:
> > 3) There is no such thing as a constructor in CFC's. To "hack"
> > (albeit a
> > known and recommended hack) then you insert code outside
> > <cffunction> tags,
> > but inside the <cfcomponent> tags. This code gets run each time
> > the CFC is
> > invoked.
>
> Almost right. The code gets run at the time the component is
> instantiated, not every time it's invoked. Hence it's common (but
> probably incorrect) name, the "constructor" code.
>
> Andy.
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