The second chapter of the book is about the repeated opening of harm, repeated into a good variety, but each repetition occurs is not necessary, repeat makes the emergence of operational efficiency of the code greatly reduced, and occupies a lot of space meaningless . To resolve duplicate the problem, the key is to learn to reuse, to fully enhance the utilization efficiency of the code, the code to do complex than their own with a new easy to knock a piece of code, so you can have problems now looking to develop reusable code, rather than directly to the new knock a piece of code.
The second section is about the benefits of orthogonality, in the process of knocking the code, I often encounter some bug resolving their time inevitably have to change to change to go around looking for problems where they occur, orthogonality is to solve this problem, orthogonality can eliminate the link between independent code, make the code more modular, clear division of labor between the various modules, a module when there is a problem, the problem is limited to put it in a module, modify or replacement can solve the problem.
The third section is revocable mainly to maintain the flexibility of the code, in the words of the book, it is a piece of code that he can automatically revoked, it must also be generated automatically.
The fourth section is my understanding that the tracer tracer is a quick look of the code with which you can quickly find the module you want to find, greatly improving the modification efficiency.
After a small section of the field is the main language is the language usage and explain some usage scenarios.
The last is about doing things for you to estimate, project estimating, estimate the approximate time to estimate the results, which have a general direction.
These are some of my thoughts after reading the second chapter of the book.