Author: Matthias Konrad
The system
In this example we are studying a simple system with three classes that contains both renaming and selects:
class
C1
feature
f1 do ... end
g1 do ... end
end
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class
C2
inherit
B
rename f1 as f2, g1 as g2
redefine f2, g2 end
feature
f2 do ... end
g2 do ... end
end
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class
C3
inherit
C2
select f2 end
C1
redefine f1, g1
select g1 end
feature
f1 do ... end
g1 do ... end
end
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This system is defined by:
The naming function
We proceed by calculating the naming function. According to its definition we have to do that incrementaly. Meaning that we first calculate then and finally .
Calculating
Since contains only one class it is sufficient to define . According to the definition:
We can forget about the right part of the union since has no base classes. So we need to calculate:
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So we get:
And hence:
Calculating
We show the calculation of the different (four) parts of the function in separate sections:
Calculate
According to the definition:
Calculate
According to the definition:
Calculate
According to the definition:
Lets calculate the left part first:
And now the right part:
So we get:
Calculate
According to the definition:
Where:
And:
Here are the steps taken to compute the part:
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So we get:
Putting the parts together:
We can know show the complete total function:
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Calculating
We will not show the complete construction of but restrict our self to the most interesting parts.
Calculate
According to the definition:
Where:
And:
Note that we can ommit from the formulas since it is always empty.
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So we get:
The complete naming function
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The dynamic binding function
To calculate the dynamic binding function, we need to get . We will again calculate it incrementaly:
Calculating
According to the definition:
Since is empty this simplifies to:
So we get:
Calculating
Again we calculate the different parts of the function in separate sections:
Calculate
According to the definition:
Calculate
According to the definition:
Calculate
According to the definition:
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So we get:
Calculate
According to the definition:
At this stage it should be clear how to calculate this, so we just give the result:
Putting the parts together:
We can know show the complete total function:
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Calculating
There is nothing new for this calculation so we just present the result:
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Deriving the dynamic binding function
The function is now given. We evaluate it at two interesting points: