Anonymous user
Null object: Difference between revisions
→Undefined values: elaborate a bit
(show how to check for undefined names in J) |
(→Undefined values: elaborate a bit) |
||
Line 294:
If you later assign a value to X in another thread, the original thread will resume and print the result of the addition. This is the basic building block of Oz' [http://c2.com/cgi/wiki?DeclarativeConcurrency declarative concurrency].
===Undefined values===
Access to undefined values (like using an out-of-range array index or a non-existing record feature) will usually provoke an exception in Oz.
It is also possible to assign a unique "failed" value to a variable. Such a failed value encapsulates an exception. This can be useful in concurrent programming to propagate exceptions across thread boundaries.
<lang oz>declare
X = {Value.failed dontTouchMe}
| |||