The process of improving a program's internal structure in small steps without modifying its external behavior is called refactoring. Refactoring is needed because 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.
Refactoring code 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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| → |
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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.