Tim O’Reilly shows how sales of O’Reilly’s books indicate a popularity of computer technologies. For example, In terms of computer languages we can see following dinamic of sales in compare with the same period of last year:
- PHP: +16%
- C#: +2.5%
- C/C++: -4%
- Python: -9%
- Java: -10
- Javascript: -12%
- Perl: -14%
- Visual Basic: -23%
As we can see, popularity of Java books and Perl books went down. That fact does not indicate reduction of popularity of those programming languages. Java is growing very fast and very often books are irrelevant. It’s much better to read specifications which reflect changes of program product very fast.