Factoring the bank account
Compying the parent slot (during):
After:
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Factoring the bank account
Why factor?
We currently have two bank account objects. If we decide to rewrite the deposit:
method, and we edit the definition in one object, it will not affect the other object.
We could propagate the new definition to the other object by copying and pasting,
but this is tedious and error-prone if there are lots of copies. We would like to share
the methods among all copies, so that a change is visible in all of them.
Making a traits object
We are going to interpose a parent object between the bank account and traits
clonable. This will be the bank account's traits object. Then, we can move behavior
from the bank account to its traits, so that when we have many bank accounts we
can modify them all by modifying the traits.
Our new traits is to inherit from traits clonable. We already have a parent slot that
refers to traits clonable, so that's a good starting point for our new object. We can
copy this slot using the middle-button menu on the slot, and drop it into the
background. This will cause a new object to be created containing this slot.
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