
readqueue - reading from a queue

Calling sequence:
readqueue(expr)
readqueue(expr, Block)

Parameter:

expr   --  expression

Summary:

readqueue(expr) reads a datum from the queue with the name expr. expr
can be any datum.  If at this time there is no value in the queue then the
function returns a datum with the type DOM_NULL    .

readqueue(expr, Block) reads a datum from the queue with the name
expr.  If at the present time there is no datum in the queue then the
function waits until a datum is written into the queue and then returns this.
readqueue is a kernel function.

See also:  writequeue , readpipe , writepipe

