Platform

Win32, x64

Purpose

To process Windows messages.

Syntax

SUBROUTINE YIELD_PROGRAM_CONTROL@(OPTION)
INTEGER OPTION

Description

This routine contains a Windows message loop. It is called automatically by ClearWin+ so that the programmer does not need to include a message loop in a program. It can be used within a program to ensure that a process does not totally take over the CPU. OPTION may be either Y_PERMANENTLY or Y_TEMPORARILY.

You may need to call this routine using Y_TEMPORARILY, if the program makes protracted use of the CPU and you want to allow it to respond to events (such as mouse events) whilst the processing continues. Call this routine at suitable points during the process to enable the message queue for the current application to be processed. Message queues for other applications that are running will automatically be processed. TEMPORARY_YIELD@ is the same as YIELD_PROGRAM_CONTROL@(Y_TEMPORARILY).

Calling this routine using Y_PERMANENTLY is equivalent to reaching the END statement of a ClearWin+ program.