OK, this is a CFML-centric article. But it's also a call to provide code analogies in different languages to a CFML example, to show the ColdFusion Team they dunno what they're on about.
Here's some CFML code:
function doit() {
var a = ["a", "b", "c"];
var b = ["x", "y", "z"];
var counter = 0;
arrayEach(a, function(foo) {
counter = 0;
arrayEach(b, function(bar) {
counter++;
// in dump counter is always 0
writeDump({
counter: counter,
foo: foo,
bar: bar
});
});
});
}
doit();
This leverages closure to reference the outer counter variable within the innermost function expression. Ergo, it's the same variable. So the expected output of this would be:
Note how the counter is declared in the main function, reset in the outer arrayEach handlers and incremented for each iteration of the inner arrayEach call. So it'll cycle through 1,2,3 three times when output.
That was run on Lucee. Running it on ColdFusion yields:
See how the counter is messed up: it's always zero. It should increment for each iteration of the inner function expression.
Adobe - being their typical selves - is claiming this is "by design":
https://tracker.adobe.com/#/view/CF-4197194:
That's nonsense.
Other languages behave predictably:
JavaScript:
function doit() {
var a = ["a", "b", "c"];
var b = ["x", "y", "z"];
var counter = 0;
a.forEach(function(foo) {
counter = 0;
b.forEach(function(bar) {
counter++;
// in dump counter is always 0
console.log({
counter: counter,
foo: foo,
bar: bar
});
});
});
}
doit();
VM128:11 Object {counter: 1, foo: "a", bar: "x"}
VM128:11 Object {counter: 2, foo: "a", bar: "y"}
VM128:11 Object {counter: 3, foo: "a", bar: "z"}
VM128:11 Object {counter: 1, foo: "b", bar: "x"}
VM128:11 Object {counter: 2, foo: "b", bar: "y"}
VM128:11 Object {counter: 3, foo: "b", bar: "z"}
VM128:11 Object {counter: 1, foo: "c", bar: "x"}
VM128:11 Object {counter: 2, foo: "c", bar: "y"}
VM128:11 Object {counter: 3, foo: "c", bar: "z"}
And PHP (apologies for the rubbish way PHP does closure):
function doit() {
$a = ["a", "b", "c"];
$b = ["x", "y", "z"];
$counter = 0;
array_walk($a, function($foo) use (&$counter, $b) {
$counter = 0;
array_walk($b, function($bar) use (&$counter, $foo) {
$counter++;
// in dump counter is always 0
var_dump([
"counter" => $counter,
"foo" => $foo,
"bar" => $bar
]);
});
});
}
doit();
array(3) {
["counter"]=>
int(1)
["foo"]=>
string(1) "a"
["bar"]=>
string(1) "x"
}
array(3) {
["counter"]=>
int(2)
["foo"]=>
string(1) "a"
["bar"]=>
string(1) "y"
}
array(3) {
["counter"]=>
int(3)
["foo"]=>
string(1) "a"
["bar"]=>
string(1) "z"
}
array(3) {
["counter"]=>
int(1)
["foo"]=>
string(1) "b"
["bar"]=>
string(1) "x"
}
array(3) {
["counter"]=>
int(2)
["foo"]=>
string(1) "b"
["bar"]=>
string(1) "y"
}
array(3) {
["counter"]=>
int(3)
["foo"]=>
string(1) "b"
["bar"]=>
string(1) "z"
}
array(3) {
["counter"]=>
int(1)
["foo"]=>
string(1) "c"
["bar"]=>
string(1) "x"
}
array(3) {
["counter"]=>
int(2)
["foo"]=>
string(1) "c"
["bar"]=>
string(1) "y"
}
array(3) {
["counter"]=>
int(3)
["foo"]=>
string(1) "c"
["bar"]=>
string(1) "z"
}
But I'm quite keen to know if there's any language that behaves as ColdFusion does in this example? If you've got a mo', could you knock out an equivalent of this code in [your language of choice], and share the results?
I'm 99.999% sure Adobe are just not quite getting closure, but wanna make sure I'm not missing anything.
Righto.
--
Adam
