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The first version of the code you write may not be of production quality. It is OK to first concentrate on making the code work, rather than worry over the quality of the code, as long as you improve the quality later. This process of improving a program's internal structure in small steps without modifying its external behavior is called refactoring.
Improving code structure can have many secondary benefits: e.g.
Given below are two common refactorings (more).
Refactoring Name: Consolidate Duplicate Conditional Fragments
Situation: The same fragment of code is in all branches of a conditional expression.
Method: Move it outside of the expression.
Example:
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Refactoring Name: Extract Method
Situation: You have a code fragment that can be grouped together.
Method: Turn the fragment into a method whose name explains the purpose of the method.
Example:
void printOwing() {
printBanner();
// print details
System.out.println("name: " + name);
System.out.println("amount " + getOutstanding());
}
void printOwing() {
printBanner();
printDetails(getOutstanding());
}
void printDetails(double outstanding) {
System.out.println("name: " + name);
System.out.println("amount " + outstanding);
}
def print_owing():
print_banner()
# print details
print("name: " + name)
print("amount " + get_outstanding())
def print_owing():
print_banner()
print_details(get_outstanding())
def print_details(amount):
print("name: " + name)
print("amount " + amount)
Some IDEs have builtin support for basic refactorings such as automatically renaming a variable/method/class in all places it has been used.
Refactoring, even if done with the aid of an IDE, may still result in regressions. Therefore, each small refactoring should be followed by regression testing.
Exercises
Results of Refactoring
Choose the correct statements.
a, b, c, d
Explanation:
Do you agree with the following statement? Refactoring and regression testing
Do you agree with the following statement? Justify your answer.
Statement: Whenever you refactor code to fix bugs, you need not do regression testing if the bug fix was minor.
There are two flaws in the given statement.
DISAGREE.
Explain Refactoring
Explain what refactoring is and why it is not the same as rewriting, bug fixing, or adding features.
Given below are some more commonly used refactorings. A more comprehensive list is available at refactoring-catalog.
You know that it is important to refactor frequently so as to avoid the accumulation of ‘messy’ code which might get out of control. But how much refactoring is too much refactoring? It is too much refactoring when the benefits no longer justify the cost. The costs and the benefits depend on the context. That is why some refactorings are ‘opposites’ of each other (e.g. extract method vs inline method).
Exercises
‘Extract method’ and ‘Inline method’ refactorings
‘Extract method’ and ‘Inline method’ refactorings
a