Steve,
First, have you tested invoking or instantiating cfc's to see what the
performance cost actually is? In my experience, and i think many people will
agree, the performance bottlenecks are usually at the database access point.
If you encapsulate your DB stuff in DAO's (the CRUD functions) and gateways
(which return query objects) i think you'll find that your lightweight
cohesive gateways don't cost much at all to instantiate, and they do most of
the front end work in most apps.
If you wanna go to town tho', and generally i can't resist the temptation,
you can instantiate your stateless gateways into a object that you store in
application scope (i won't qualify what that object might be ... different
apps probably could and should have very different architectures), pass in
the dsn stuff once only, and hit your cached gateways for the rest of the
day and night for free.
But again, it's very unlikely your performance bottleneck will show up here
under stress testing, but i like writing code like this. ;)
<cffunction name="init" access="public"
returntype="myCachedInAppScopeObject" output="no">
<cfargument name="dsn" type="string" required="true" />
<cfset generateGatewayObjects()>
<cfreturn this />
</cffunction>
.....
<!--- factory section --->
<cffunction name="generateGatewayObjects" access="private" returntype="void"
output="no">
<cfset setEventGateway() />
<cfset setFAQGateway() />
<cfset setFlashGateway() />
<cfset setImageGateway() />
<cfset setPageGateway() />
<cfset setPersonGateway() />
<cfset setProductGateway() />
<cfset setTextGateway() />
<cfset setUserGateway() />
</cffunction>
<!--- EVENT GATEWAY --->
<cffunction name="setEventGateway" access="private" returntype="void"
output="no">
<cfset variables.EventGateway =
createObject('component','myMapping.dao.EventGateway').init(variables.dsn)
/>
</cffunction>
<cffunction name="getEventGateway" access="public"
returntype="myMapping.dao.EventGateway" output="no">
<cfreturn variables.EventGateway />
</cffunction>
etc ...
:) Nando
-----Original Message-----
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]
Behalf Of Steve Bryant
Sent: Thursday, September 30, 2004 3:48 AM
To: [EMAIL PROTECTED]
Subject: Re: [CFCDev] Encapsulation and Request vars (was Function
Libraries)
That does seem like good encapsulation.
How would I go about doing that? Would I need to do that in my init method?
If so, does this also limit my ability to use a method without first
instantiating the component. Again, I am not married to that approach it
just seems handy for rarely used methods in rarely used objects.
If using cfinvoke as I am is a bad practice, I would certainly like to
understand when it should be used so that I can adjust my practices
accordingly. I would also like to understand the performance implications
of instantiating the object every time. Am I worrying about that for
nothing? I am expecting the site to be pretty high-traffic so I am
abnormally concerned with performance.
Thanks and sorry for all of the question!
Steve
At 08:33 PM 9/29/2004, you wrote:
>Steve,
>
>Although I am not an OO or good design guru and someone might guide
>you a better design decision however what about having all your dsn
>variables i.e dns name, username, password etc as an instance variable
>of a DAOConstants cfc.. For all other CFCs in your model you can
>essentially composite this DAOConstants cfc and get those variables by
>calling the getter method on your contants CFC. Hope it helps
>
>Qasim
>
>
>On Wed, 29 Sep 2004 20:19:38 -0500, Steve Bryant
><[EMAIL PROTECTED]> wrote:
> > I have a practical question to bring to this little discussion.
> >
> > I am currently coding my first site which makes large-scale (for me) use
of
> > CFCs. Most of these CFCs access the database for the site. I am
currently
> > using a request variable to store the datasource. I am not doing this
> > because I don't believe in the value of encapsulation, but rather
because I
> > can't figure out a better way to handle it.
> >
> > I don't want to pass the datasource in to each and every method. I don't
> > want to incur a bunch of overhead in getting the datasource for query in
> > every method. I do want to be able to invoke some methods (via cfinvoke)
> > without first instantiating the object.
> >
> > I am certainly missing some good practice of which others are aware. I
> > would love to be enlightened.
> >
> > Thanks All!
> >
> > Steve
> >
> > At 07:35 PM 9/29/2004, you wrote:
> > >You are, of course, free to do whatever you like. But encapsulation has
> > >a huge history of benefits and I'm afraid your opinion isn't going to
> > >put the slightest dent in that history.
> > >
> > >In your example, I would argue that you should indeed be passing the
CGI
> > >variable into the CFC and not calling it directly. There's absolutely
no
> > >reason to do call it directly, the "cost" of passing it in is
miniscule,
> > >but the benefits of well-encapsulated code are thoroughly confirmed.
The
> > >same applies to calling request-scoped UDF's from within a CFC: it's
> > >totally unnecessary. In fact, why are the UDF's in the request scope
> > >anyway? I'd say, move them into an object and call them through the
> > >object. If another CFC needs to use them, I'll pass in the object.
> >
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