New to Objects - calling methods and functions

[Chris Holbrook]

' New to POO? Programming objects for the first time
'
' very simple example to show that
' a) you can call a class method from your main program and
' b) that it can call a "regular" function, and pass its own handle
' c) and the "regular" function can thus call the interface's methods
'    without much fuss.
' d) Oh, and that just initialising the object calls the create Class Method
' e) ...and that discarding the object calls the Destroy method"
'
' Chris Holbrook Feb 2009
'
#compile exe
#dim all
#debug display on  '<=========== a VERY GOOD THING when you first test the program
                   '             if an error occurs it will display details and prompt you
                   '             you will want to turn it off if you use the stepping deugger!
'-------------------------------------------
function stdfun ( x as InterfaceX ) as long  '<======= The interface name used as the TYPE
                                             '         of the parameter
     function = x.b       '<================= call the Interface's 'b' method
end function
'-------------------------------------------
class classX
    class method create
        ? "Hello, Creator!"
    end method
    class method Destroy
        ? "Goodbye, World! it was fun while it lasted!"
    end method
    interface InterfaceX
        inherit iunknown  '<======= you have to do this apparently
                          '         I'm not going to argue about it
                          '         ...just try leaving it out!
        '-----------------------------------
        method a
            local l as long

            ? "method 'a' here!"
            l = stdfun(me) '<============== call the regular function
                           '                passing the OBJECT handle - in this case,
                           '                the OBJECT is the InterfaceX interface
            ? str$(l)
        end method
        '-----------------------------------
        method b as long
            method = 1234
        end method
        '-----------------------------------
    end interface
end class
'------------------------------------------
function pbmain () as long
    local xif as InterfaceX

    xif = class "classX" '<==== you have to do this too, to initialise the object
    xif.a                '<==== call the interface's 'a' method
    xif = nothing        '<==== tidying up by discarding the object
                         '      pretty irrelevant in THIS application
                         '      but could be essential - get into the habit!
end function