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How to write programs
Applications are event-driven. I.e. they respond to desktop events such as selecting a menu-entry, clicking an action button, etc. When a desktop event occurs an AppBasic application calls one (or more) standard procedures known as the event handlers. Programming consists of amending the definitions of these procedures. For example, an iconbar event would call the procedure:
DEF PROCDealWith_Iconbar(event,object,component)
CASE event OF
WHEN Iconbar_Clicked
CASE component OF
WHEN 0 : REM Select
WHEN 1 : REM Adjust
ENDCASE
WHEN Iconbar_SelectAboutToBeShown
WHEN Iconbar_AdjustAboutToBeShown
ENDCASE
ENDPROC
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To display the message “Hello world” when the iconbar icon is selected, you could amend the above procedure to
DEF PROCDealWith_Iconbar(event,object,component)
CASE event OF
WHEN Iconbar_Clicked : PROCUtils_Alert(“Hello world”)
ENDCASE
ENDPROC
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