How to handle errors without execution halting - ibm-doors

Question

I have a small dxl script and I need to return the number of assigned positions from an array of, let's say, size 20 in which only 10 positions are assigned.
I tried to use noError() and lastError() functions, but after lastError() is called, the script is halted and I can't continue the execution.
Here's my code:
int returnArrayLength(string array[]){
int lengthOfArray = 0,i = 0;
for (i=0; i < sizeof array ; i++){
noError()
if (!null array[i]){
lengthOfArray++
print lengthOfArray
}
if (!null lastError()){
print "Exception caught!" // not printed
break
}
}
return lengthOfArray
}
string labels[6]
labels[0] = "label0"
labels[1] = "label1"
labels[2] = "label2"
labels[3] = "label3"
print returnArrayLength(labels) // not printed
The above code prints the following:
1
2
3
4
How can I resume the execution after the lastError() function is called ?

Answer 1

This was tougher than I thought it would be!
So, as it turns out, an unassigned element error halts the DXL program entirely. So what do we need to do?
Well, we need to run a snippet of code, in it's own environment, and let it crash if it needs to!
To do so, we need to create an eval_, pass it our array, and then have it return_ (which won't be executed if the eval_ fails)
Take a look:
int returnArrayLength(string array[]){
int lengthOfArray = 0,i = 0;
for (i=0; i < sizeof array ; i++){
string scode = "noError()
string ( &passedAr)[] = (addr_ "( ( addr_ array ) int ) ")
string s = passedAr["i"]
lastError()
return_ \"Y\""
if ( ( eval_ scode ) == "Y" ){
lengthOfArray++
print lengthOfArray
} else {
print "Exception caught!" "\n"
break
}
}
return lengthOfArray
}
string labels[6]
labels[0] = "label0"
labels[1] = "label1"
labels[2] = "label2"
labels[3] = "label3"
print returnArrayLength(labels)
What a fantastic little problem.
Resources I used to help solve this:
How to pass an array into an eval_
eval_ , addr_ , and memory leaks
Testing for unassigned variables - This one doesn't quite work because of the nature of arrays, at least as far as I could tell!
In any case, thanks for the challenge!