Figure 5.5: Last Object In is the First Out

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COMPOSITE OBJECTS

The values associated with composite objects do not exist on the operand stack. There is an object on the stack that represents the composite object data, and it behaves, for the most part, as though the whole object were on the stack. The only time it is confusing is during copying and manipulation of the internal structure of a composite object, when you have to realize that you really have a pointer to the object, not a selfcontained object. For example, if you dup a string object and then change one of the letters in the copied object, the original string changes, too, since there really is only one string and you have only copied the pointer to it, not the string itself.

Figure 5.6: Duplicating a Composite Object