The pragmatic programmer
- 1. THE PRAGMATIC PROGRAMMER CHAPTER 3 THE BASIC TOOLS
- 2. HEADLINES The Power Of Plain Text Shell Games Power Editing Source Code Control Debugging Text Manipulation Code Generators
- 3. PLAIN TEXT As programmers our base material = KNOWLEDGE We gather requirements as knowledge and then express in our designs. We believe the best format for storing it is PLAIN TEXT HUMAN-READABLE AND SELF-DESCRIBING !! Fieldl9=467abe DrawingType=UMLActivityDrawing myprop.uses_menus=FALSE Contrast this with 0010010101110101
- 4. DRAWBACKS 2 major drawbacks to using plain text: 1.It may take more space to store than a compressed binary format. 2.It may be more expensive to interpret and process a plain text file.
- 6. THE POWER OF PLAIN TEXT Insurance Against Obsolescence As long as the data survives, you will have a chance to be able to use it. <FIELD10>123-45-6789</FIELD10> AC27123456789B11P <FIELD10>567-89-0123</FIELD10> XY43567890123QTYL <FIELD10>901-23-4567</FIELD10> 6T2190123456788AM Leverage Virtually every tool in the computing universe can operate on plain text. Easier Testing It is a simple matter to add, update, or modify the test data without having to create any special tools.
- 7. THE UNIX PHILOSOPHY The philosophy is enabled by using a common underlying format-line oriented, plain text file. Databases used for system administration -users -passwords -network config, all kept in a plain text files.
- 8. SUMMARY YOU NEED TO ENSURE THAT ALL PARTIES CAN COMMUNICATE USING A COMMON STANDART. PLAIN TEXT IS THAT STANDART.
- 9. SHELL GAMES For a programmer manipulating files of text, workbench is the command shell. You can launch applications, debuggers, browsers, editors, and utilities. You can search for files, query the status of the system. If you do all your work using GUIs, you are missing out on the full capabilities of your environment. A benefit of GUIs is WYSIWYG—WHAT YOU SEE IS WHAT YOU GET. The disadvantage is WYSIAYG—WHAT YOU SEE IS ALL YOU GET.
- 10. SHELL VS GUI
- 11. POWER EDITING One Editor We think it is better to know one editor very well, and use it for all editing tasks: code, documentation, system administration, and so on… If you use a single editor (or set of key bindings) across all text editing activities, you don't have to stop and think to accomplish text manipulation
- 12. Editor Feautures CONFIGURABLE EXTENSIABLE PROGRAMMABLE Also have: Syntax highlighting Auto-completion Auto-indentation Initial code or document boilerplate Tie-in to help systems IDE-like features (compile, debug, and so on)
- 14. SOURCE CODE CONTROL One of the important things we look for in a user interface is the key—a single button that forgives us our mistakes !!!!! Source code control systems, or the more widely scoped configuration management systems, keep track of every change you make in your source code and documentation. Who made changes in this line of code? What's the difference between the current version and last week's? How many lines of code did we change in this release?
- 15. DEBUGGING In 1873 Edison first confronted what he later called a bug when he began developing a quadruplex telegraph system. On September 9, 1945, a Harvard technical team looked at Panel F and found something unusual between points in Relay 70.It was a moth, which they promptly removed and taped in the log book.
- 16. DON’T PANIC Don't waste a single neuron on the train of thought that begins "but that can't happen" because quite clearly it can, and has… It is very important to step back a pace, and actually think about what could be causing the symptoms that you believe indicate a bug.
- 17. WHERE TO START? Before you start to look at the bug, make sure that you are working on code that compiled cleanly—without warnings When trying to solve any problem, you need to gather all the relevant data.
- 18. DEBUGGING STRATEGIES Bug Reproducing We want a bug that can be reproduced with a single command Visualize your data The simplest example of this is a straightforward "variable name = data value" approach, which may be implemented as printed text. The DDD debugger has some visualization capabilities, and is freely available .It is interesting to note that DDD works with multiple languages, including Ada, C, C++, Fortran, Java, Modula, Pascal, Perl, and Python (clearly an orthogonal design).
- 19. DEBUGGING STRATEGIES Tracing Debuggers generally focus on the state of the program now. Sometimes you need more—you need to watch the state of a program or a data structure over time. Rubber Ducking
- 20. DEBUGGING STRATEGIES Process Of Elimination It is possible that a bug exists in the OS, the compiler, or a third-party product—but this should not be your first thought It is generally more profitable to assume that the application code is incorrectly calling into a library than to assume that the library itself is broken
- 21. DEBUGGING CHECKLIST • • Is the problem being reported a direct result of the underlying bug, or merely a symptom? • • Is the bug really in the compiler? Is it in the OS? Or is it in your code? • • If you explained this problem in detail to a coworker, what would you say? • • If the suspect code passes its unit tests, are the tests complete enough? What happens if you run the unit test with this data? • • Do the conditions that caused this bug exist anywhere else in the system?
- 22. DEBUGGING CHALLENGES • • Debugging is challenge enough...
- 23. TEXT MANIPULATIO N Pragmatic Programmers manipulate text the same way woodworkers shape wood. In previous sections we discussed some specific tools— shells, editors, debugger. We happen to prefer Perl for hacking out short scripts. Kernighan and Pike built the same program in five different languages. The Perl version was the shortest (17 lines, compared with C's 150). With Perl you can manipulate text, interact with programs, talk over networks, drive Web pages, perform arbitrary precision arithmetic, and write programs.
- 24. CODE GENERATORS We need to achieve the same functionality, but in different contexts. We need to repeat information in different places. A programmer can build a code generator. Once built, it can be used throughout the life of the project at virtually no cost.
- 25. WRITE CODE THAT WRITE CODES 1. Passive code generators Run once to produce a result. From that point forward, the result becomes freestanding—it is divorced from the code generator. 2. Active code generators The result is a throw-away—it can always be reproduced by the code generator.
- 26. ANY QUESTIONS?