...
| Argument | Type | Description |
|---|---|---|
| list | Any | The list to which value should be added. If this argument is a variable which evaluates to null then a new list will be returned containing only value. If this argument is not a list but a single value then a new list will be returned containing this argument and value. |
| value | Any | The item that should be added to list |
...
If in.rate is not found then an error message is added to a list of errors found so far. An If() condition is a useful way of building up a list of problems which are found as a Stream is processed.
listToString() can be used to format a list (of errors, say) into a string that can be recorded in a string-valued field on a stream record. Given a list like:
$errors = ["Bad input", "Missing rate value"],
the expression
listToString($errors, "\n") and listToString($errors, ", ")
will generate output strings like:
"Bad input
Missing rate value"
and
"Bad input, Missing rate value"
respectively.