OriginalPeople
- The most important factor in software work is the quality of the programmers.
- The best programmers are up to 28 times better than the worst programmers.
- Adding people to a late project makes it later.
- The working environment has a profound impact on productivity and quality.
Tools and Techniques
- Hype (about tools and technology) is a plague on the house of software.
- New tools and techniques cause an initial loss of productivity / quality.
- Software developers talk a lot about tools, but seldom use them.
Estimation
- One of the two most common causes of runaway projects is poor estimation.
- Software estimation usually occurs at the wrong time.
- Software estimation is usually done by the wrong people.
- Software estimates are rarely corrected as the project proceeds.
- It is not surprising that software estimates are bad. But we live and die by them anyway!
- There is a disconnect between software management and their programmers.
- The answer to a feasability study is almost always "yes".
Reuse
- Reuse-in-the-small is a solved problem.
- Reuse-in-the-large remains a mostly unsolved problem.
- Reuse-in-the-large works best in families of related systems.
- Reuseable components are three times as hard to build and should be tried out in three different settings.
- Modification of reused code is particularly error-prone.
- Design pattern reuse is one solution to the problems of code reuse.
Requirements
- One of the two most common causes of runaway projects is unstable requirements.
- Requirements errors are the most expensive to fix during production.
- Missing requirements are the hardest requirements errors to correct.
Design
- Explicit requirements 'explode' as implicit requirements for a solution evolve.
- There is seldom one best design solution to a software problem.
- Design is a complex, iterative process. Initial design solutions are usually wrong and certainly not optimal.
Coding
- Designer 'primitives' rarely match programmer 'primitives'.
- COBOL is a very bad language, but all the others are so much worse.
Error removal
- Error removal is the most time-consuming phase of the lifecycle.
Testing
- Software is usually tested at best to the 55 to 60 percent coverage level.
- 100 percent test coverage is still far from enough.
- Test tools are essential, but rarely used.
- Test automation rarely is. Most testing activities cannot be automated.
- Programmer-created, built-in debug code is an important supplement to testing tools.
Reviews and Inspections
- Rigorous inspections can remove up to 90 percent of errors before the first test case is run.
- Rigorous inspections should not replace testing.
- Post-delivery reviews, postmortems, and retrospectives are important and seldom performed.
- Reviews are both technical and sociological, and both factors must be accommodated.
Maintenance
- Maintenance typically consumes 40 to 80 percent of software costs. It is probably the most important software lifecycle phase.
- Enhancements represent roughly 60 percent of maintenance costs.
- Maintenance is a solution-- not a problem.
- Understanding the existing product is the most difficult maintenance task.
- Better methods lead to more maintenance, not less.
Quality
- Quality is a collection of attributes.
- Quality is not user satisfaction, meeting requirements, achieving cost and schedule, or reliability.
Reliability
- There are errors that most programmers tend to make.
- Errors tend to cluster.
- There is no single best approach to software error removal.
- Residual errors will always persist. The goal should be to minimize or eliminate severe errors.
Efficiency
- Efficiency stems more from good design than good coding.
- High-order language code can be about 90 percent as efficient as comparable assembler code.
- There are tradeoffs between optimizing for time and optimizing for space.
Research
- Many researchers advocate rather than investigate.
Extract - Revisiting The Facts and Fallacies of Software Engineering
2008.04.13. 19:17 takacsot
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