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A fifth virtue of procedure abstraction is that you can improve how a computation is
done. You might decide, for example, that it is wasteful for your
fatToCalories method to multiply out self and 9 twice.
Accordingly, you might decide to do the computation just once, using a
variable, named result, to hold onto the value:
Integer method definition • instance fatToCalories | result | result := self * 9. Transcript show: 'The number of fat calories computed is '; show: result printString; cr. ^ result
Again, you do not need to find all the places where calories are
computed from fat grams; you need to change only the definition of the
fatToCalories method.