>> I have a custom tag that wants to use application
>> variables
>> (for performance). Since you need to run a cfapplication
>> tag
>> to use the application scope, it needs to somehow check
>> if
>> that tag has run. I have no clue how to do this. Is it
>> possible?
> I would think that you should be able to do this:
> <cfif IsDefined("Application")>
> ... the application scope exists! Woohoo! ...
> </cfif>
You can do this -- although on CF5 you may not want to for reasons I won't get into in
depth.
I've never run into a situation where I wasn't sure if the <cfapplication> tag had
been executed, so I guess the context eludes me. I tend to also create a request
structure with variables for all my <cfapplication> settings, such as
sessionmanagement, sessiontimeout, clientstorage, setclientcookies, etc. and then use
those request variables in the <cfapplication> tag, which allows me to also use those
request variables to determine how my cfapplication is configured, for instance, I can
determine the duration of sessions by checking request.myapp.timeout_session or
determine if session variables are enabled by checking request.myapp.sessionmanagement
... On CF5 and prior this is helpful for getting at this information without continual
locking.
It can also be used to manage movement between disparate applications since you can
run the <cfapplication> tag more than once on a page -- if you use a different name
for the application the 2nd time, then content after the 2nd cfapplication tag will
see all the application and session variables from the 2nd application and none from
the 1st. But if you have the data already stored in a request structure, you can then
duplicate it into a temp variable, drop into the 2nd application and then return to
the original application. Think of it as a cf-application management application. :)
In the wider IT world it's called Software Configuration Management (SCM). Of course,
if you name the request variables distinctly, i.e. request.app1, request.app2 or
request.apps.primary and request.apps.secondary then you can have access to all of the
data for all the apps at all times and just pick and choose between different apps by
including their <cfapplication> tags (store them in modules that can be included using
cfinclude).
Anyway -- I've gotten way off the original subject. :)
>> Also, just to make sure - custom tags do have
>> normal access to the application scope, correct?
> Yes, although in general, when you write code modules,
> you may want to limit
> access to and from the modules to defined inputs and
> outputs.
Generally speaking imho it's best for custom tags to be "black boxes" if possible, in
other words, feed it everything it needs as an attribute, and know what it returns (if
anything). That way other templates never have to know anything about how the custom
tag functions, all they have to know is what to pass to the tag and what to expect in
response. Imho if you plan to use the custom tags directory, don't use the application
scope directly -- feed those variables to it as attributes. Otherwise call the tags
using relative paths (which is what I do anyway, and imho is better since it's more
controlled), or a cf server mapping (which I avoid for the reason that they're
difficult to get if you have shared hosting).
s. isaac dealey 972-490-6624
new epoch http://www.turnkey.to
lead architect, tapestry cms http://products.turnkey.to
tapestry api is opensource http://www.turnkey.to/tapi
certified advanced coldfusion 5 developer
http://www.macromedia.com/v1/handlers/index.cfm?ID=21816
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