you have to make a method return an instance of the class itself. Because this is an object that is returned, you can then invoke another method on the returned object
so:
class foo:
def property bar as char no-undo get . set .
method public foo MethodA():
/** do stuff */
return this-object.
end method.
method public foo MethodB():
/** do stuff */
return this-object.
end method.
end class.
/** procedure a */
def var a as foo no-undo.
a = new foo().
message a:MethodA():MethodB():bar view-as alert-box.
/** procedure b */
message (new foo()):MethodA()
:MethodB()
bar
view-as alert-box.