Dynamic inheritance
- Assigning to a parent slot changes the inherited behavior of an object.
- Usually used to switch between states where behavior is significantly different.
- Use with caution!
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Dynamic inheritance
Because parent slots are potentially assignable, we have a new concept in
Self not present in class-based languages such as Smalltalk, C++ and
Eiffel: dynamic inheritance.
Using dynamic inheritance, an object can change one or more of its parents during
execution.
Typically, this is used when an object can be in one of a small number of discrete
states, each having significantly different behavior from the others. An example is
the object unix, which represents the Unix system call interface. It has a dynamic
parent, currentOsVariant, which can be set to an object containing behavior specific
to a particular variant of Unix; this is done every time the system is started.
Dynamic inheritance should be used with caution: it is easy to construct programs
which are very hard to understand!
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