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Why not code everything in C?

Explore the problems of software development and why object-oriented programming (OOP) can help reduce complexity, improve testability, and promote code reuse. Discover why industry experts, like Frederick Brooks, believe in the benefits of OOP.

arlenereynolds
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Why not code everything in C?

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  1. Why not code everything in C? James Brucker Why Object-oriented Programming?

  2. Problems of Software Development 1. Software is Complex. • Microsoft Office had 30,000,000 lines of code in 2006. Mostly C++. https://blogs.msdn.microsoft.com/macmojo/2006/11/02/its-all-in-the-numbers/ • Apache Web server (httpd) has 1,832,007 lines of code. Mostly C. https://www.openhub.net/p/apache

  3. Problems of Software Development 2. Software changes.Lots of change • requirements change • our understanding changes • technology changes ...and it happens during the project Apache httpd: 2,805 Commits in last 12 months 28 Contributors

  4. Problems of Software Development 3. Modeling real-world problems is hard. Modeling mismatch: Behavior of real things does not match behavior of software components.

  5. Problems of Software Development 4. Software tends to have a lot of defects. This is partially a result of complexity, change, and modeling mismatch. It also is related to our development process

  6. Problems of Software Development 5. Software is expensive to develop and maintain. Too much change, complexity, and mismatch. Too many defects. Lack of standard components. Too much "custom development".

  7. What We Want • Reduce complexity... divide into simple parts • Hide details inside the parts • Easy to change or replace. • Model software closely to real-world objects • Improve testability... to reduce bugs. • Reuse code... to reduce cost. • Reuse entire applications... just "plugin" custom features.

  8. OO reduces complexity Divide a program into simple classes • each class has a single responsibility Encapsulatecomplexity • each class has its own responsibilities and data • class has a well-definedinterface • hide implementation and data

  9. Easy to Change Classes are loosely coupled • class depends only on behavior of other classes • don't depend on how behavior is implemented • depend on only a few classes as a result... • localize the effect of change

  10. Modeling is Simpler Objects resemble "real world" things: • they have behavior • they have knowledge or state • they relate to other objects (things) Let us think about the problem instead of the code Help to simplify the problem by encapsulating details.

  11. Code Reuse • classes with few dependencies are reusable in other applications • polymorphism lets us substitute one class for another one • inheritance lets us build new classes that reuse code from old classes • combining these 3, we can reuse (almost) entire applications. Called frameworks.

  12. Easier to Test • we can test each class by itself (unit testing) • we can test a group of classes together (component testing, integration testing)

  13. Intrinsic Complexity of Software "Thereisnosingledevelopment, in either technology or in management technique, that by itself promises even one orderofmagnitude improvement in productivity, reliability, or simplicity." "No Silver Bullet" by Frederick Brooks. Computer, 1987 What does he think of O-O Programming? ...

  14. Brooks on O-O "Many students of the art hold out more hope for object-oriented programming than for any of the other technical fads of the day. I am among them." "No Silver Bullet" by Frederick Brooks. Computer, 1987 Read the article to learn why Brooks believes in O-O programming.

  15. Miller’s Law and Complexity At any one time, a person can concentrate on at most 7  2 chunks (units of information) • Need to limit complexity. • How to limit complexity? • hide it! • modular design • only use a module's public interface • limit dependencies between modules

  16. Procedural vs O-O Paradigm http://www.youtube.com/watch?v=D8jZ0l_GwXQ

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