Refactoring: Improving the Design of Existing Code

They realized that refactoring was important in improving their productivity

Smalltalk is an environment that even then was particularly hospitable to refactoring.

Two of the first people to recognize the importance of refactoring were Ward Cunningham and Kent Beck,

Ward Cunningham and Kent Beck,

Having a well-factored program helps with this style of optimization in two ways. First, it gives me time to spend on performance tuning. With well-factored code, I can add functionality more quickly. This gives me more time to focus on performance.

That change doubled the speed of the system, enough for the tests to be bearable. It took us about five minutes.

ranges were empty!

They were all going through a string conversion even though no external inputs were involved. The code was just using string conversion for convenience of typing.

slowly. Although we were still in development, it began to bother us, because it was slowing down the tests.

Kent Beck, Martin Fowler, and I decided we’d fix it up. While I waited for us to get together, I was speculating, on the basis of my extensive knowledge of the system,

Changes that improve performance usually make the program harder to work