Thankfully for me (and anyone who is interested in using his closures package), Sean Corfield
reponded to my
Beauty of Closures post and set me straight on a couple of issues.
First, he confirmed that there was indeed a bug when attempting to use a mapping to use the closures, and that in fact, it wasn't a CF 6.1 issue only.
Next, he dove right into the code. So, for easy reference, here is my original code:
<!--- container.cfc --->
<cfcomponent>
<cfscript>
variables._arr = arrayNew(1);
variables._curIndex = 0;
// adds an element to the container
function add(value)
{
_curIndex = _curIndex + 1;
_arr[_curIndex]=value;
}
// iterates over the container, letting a closure
// specify what to do at each iteration
function each(closure)
{
closure.name("run");
for (i=1; i lte _curIndex; i=i+1)
{
closure = closure.bind(value=_arr[i]);
closure.run();
}
}
</cfscript>
</cfcomponent>
His
each() method is only slightly different from mine, but significantly so:
// iterates over the container, letting a closure
// specify what to do at each iteration
function each(closure)
{
for (i=1; i lte _curIndex; i=i+1)
{
closure.call(_arr[i]);
}
}
He mentions that I "[name] the method and then repeatedly [bind] the value variable. That doesn't actually do what he thinks." He's right. I was using it incorrectly, and I thought that it was sort of odd to do it like that. In particular, I didn't like having to name the closure. This syntax is much cleaner, and easier to understand. And the best part follows: I had mentioned that, "from my understanding of closures, you should be able to modify 'outer' variables within them. Thus, to be a 'true' closure, outputting
beenhere above
should show true" in reference to this code:
<!--- closure_test.cfm --->
<cfscript>
cf = createObject("component","org.corfield.closure.ClosureFactory");
container = createObject("component","container");
container.add(10);
container.add(20);
container.add(30);
beenhere = false;
c = cf.new("<cfset value = value + 3><cfoutput>#value#</cfoutput><cfset beenhere = true>");
container.each(c);
c = cf.new("<br/><cfoutput>This container has the value #value# in it</cfoutput>");
container.each(c);
</cfscript>
<cfoutput>
#beenhere# <!--- outputs false --->
</cfoutput>
Sean shows that in fact, had I used
bind() as it was intended, outputting
beenhere would have shown true, as expected. Basically, you can use
bind(outer=variables) on the closure to get access to it. Then, in the code for the closure, you could use
outer.beenhere = true and of course, the value is changed as you would expect. That is close to what I was thinking of when I said my idea would muck up the syntax, but I was thinking of passing it when creating the object. I actually like this a little better, as it is much cleaner than what I envisioned, and it is easier to see what's going on. It would be nice of course, if there was a way to do it without the programmer worrying about it, but I don't think that is possible with CF, since it uses the the same name for (from what I can tell) are two different scopes.
Anyway, thanks again to Sean for cleaning up my mess.
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