Multi-Threading Language Elements

The following language elements are provided to support threads.

• Primitive operator, spawn: &.
• System functions: ⎕TID, ⎕TCNUMS, ⎕TNUMS, ⎕TKILL, ⎕TSYNC.
• An extension to the GUI Event syntax to allow asynchronous callbacks.
• A control structure: :Hold.
• System commands: )HOLDS, )TID.
• Extended )SI and )SINL display.

Running Callback Functions as Threads

A callback function is associated with a particular event via the Event property of the object concerned. A callback function is executed by ⎕DQ when the event occurs, or by ⎕NQ.

If you append the character & to the name of the callback function in the Event specification, the callback function will be executed asynchronously as a thread when the event occurs. If not, it is executed synchronously as before.

For example, the event specification:

      ⎕WS'Event' 'Select' 'DoIt&'

tells ⎕DQ to execute the callback function DoIt asynchronously as a thread when a Select event occurs on the object.