I have a question on the subject of Singletons, opinions solicited. Allow me to
illustrate my question by comparing what I consider to be two nearly equivalent
means of executing the Singleton pattern:
scenario A (the object written exactly right):
<!-- create the singleton.... -->
<cfset application.objUtilities = createobject("cfc","model.utilities") />
<!-- utilize the singleton... -->
<cfset myResults = application.objUtilities.getResults() />
Scenario B (the object written questionably):
<!-- create the singleton.... -->
<cfset application.objUtilities = createobject("cfc","model.utilities") />
<!-- utilize the singleton... -->
<cflock name="getresults" timeout="10" throwontimeout="no" type="exclusive">
<cfset myResults = application.objUtilities.getResults() />
</cflock>
At times, writing a CFC that is to be utilized as a singleton can be a bit
tricky for me...trying to visualize it being accessed by multiple users
simultaneously leaves me thinking that maybe there's something I overlooked.
So, it occurred to me to simply wrap my singleton call in a cflock tag, then
there's no doubt at all that my singleton calls won't be stepping on each
other's toes.
So the question is, first of all, how does wrapping an object call in cflock
tags strike you as a developer? Does it seem hacky or otherwise unsettling?
Secondly, can a cfc (generally speaking) act as a singleton if we do wrap it in
an exclusive lock like that? Of course I know that a lot of the answer depends
upon how the CFC is written, but assuming the object isn't persisting values
between calls, would you consider something like this acceptable, or is it far
far from best practice?
Lastly, can anybody offer or point me to some resources that provide good solid
guidelines to follow when writing a CFC that is to be utilized as a Singleton?
Thanks!
Doug B
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