Artificial Events

• the MT Icon function

event(code, value)

produces an artificial event as if the event occurred in the run-time system

• there are two categories of artificial events:

virtual events, mimicking real events
pseudo-events, used for inter-task communication

• the event codes for virtual events are one-character strings as for real events
  
• for example, event(E_String, 10) produces a virtual event indicating the allocation of a 10-character string
  
• virtual event codes are not limited to those for real events, but if others are used, the SP and MP must share knowledge of them, and care needs to be taken to avoid conflict between virtual event codes and real event codes
  
• the event codes for pseudo-events can be anything except one-character strings
  
• EvGet() ignores events whose codes are not one-character strings unless its second argument is nonnull
  
• for example,

EvGet(EmptyMask, 1)

accepts only pseudo-events

• artificial events can be used by an SP to explicitly communicate with an MP
  
• for example, instances of event() could be inserted by an IMT to provide event reports for control structures, to tell MP to start or stop accepting pseudo-events, and so on