Special Variables - SBCL 1.0.31 User Manual
Description: SBCL 1.0.31 User Manual

Next: Mutex Support, Previous: Threading basics, Up: Threading

### 12.2 Special Variables

The interaction of special variables with multiple threads is mostly as one would expect, with behaviour very similar to other implementations.

- global special values are visible across all threads;
- bindings (e.g. using LET) are local to the thread;
- threads do not inherit dynamic bindings from the parent thread

The last point means that

         (defparameter *x* 0)
         (let ((*x* 1))
           (sb-thread:make-thread (lambda () (print *x*))))

prints `0` and not `1` as of 0.9.6.