Duplicated Code

Duplicated Code does not need further explanation. According to Fowler, redundant code is one of the worst smells [1]. One thing is that this makes it more challenging to read the program. Checking whether the copies are identical is yet another issue - looking at whether there are for sure no tiny differences between code blocks in search of Oddball Solution further unnecessarily absorbs developer time. Yet another thing is that whenever a change is made, one needs to check if this should have happened to just one or all of the existing copies of code, wherever they are.

Refactoring:

• Extract Class
• Extract Function
• Pull Up Method
• Slide Statement
• Form Template Method

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Sources

• [1], [Origin] - Martin Fowler, "Refactoring: Improving the Design of Existing Code" (1999)