| Recipe 2.10: 'Finalizing' the Implementation of a Method |
Last Updated: Sep 8, 2003
Status: Draft
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Problem:
You want to prevent subclasses -- or anyone else -- from changing the implementation of a method.
Solution:
Use the is final property:
method do_something(...) is final { ... }
Discussion:
There are circumstances in which you know the implementation of a method will never change; at least, you hope it won't, and you want perl to catch any attempts to override the method. That's what the is final does: it enforces the "finality" of a the method, such that the implementation given to the method may not be overriden.
Note that is final is very different from is interface. The is interface property declares that the interface, or signature of the method may not be altered. The is final property declares that the implementation of the method may no longer be altered.
Thus, is final implies is interface, but the reverse is not true.
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