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Вы можете ознакомиться и скачать презентацию на тему Code quality. Доклад-сообщение содержит 46 слайдов. Презентации для любого класса можно скачать бесплатно. Если материал и наш сайт презентаций Mypresentation Вам понравились – поделитесь им с друзьями с помощью социальных кнопок и добавьте в закладки в своем браузере.

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Tell me, what is a clean code for you?

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$for (i = 0;i < strlen(line);i++) { short char_code = isupper(line[i]) ? line[i] - 64 : line[i] - 96; if (char_code > 0 && char_code < 27) { printf("%c", isupper(line[i]) ? ((char_code + step) % 26 + 64) : ((char_code + step) % 26 + 96)); } else { printf("%c", line[i]); } }$

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for (i = 0;i < strlen(line);i++) { short char_code = isupper(line[i]) ? line[i] - 64 : line[i] - 96; if (char_code > 0 && char_code < 27) { printf("%c", isupper(line[i]) ? ((char_code + step) % 26 + 64) : ((char_code + step) % 26 + 96)); } else { printf("%c", line[i]); } }

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void CEquation::trio(double array[][rt+1],double alfa[][rt+1]) { for (int L = 0; L<rt-1;L++) { for(int k = 1+L; k<rt+1; k++) { alfa[L][k] = - (array[L][k]/array[L][L]); for (int i=L+1;i<rt;i++) array[i][k] = array[i][k] + array[i][L]*alfa[L][k]; } } alfa[rt-1][rt+1-1]= - array[rt-1][rt+1-1]/array[rt-1][rt-1]; }

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Good vs Bad

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How to write beautiful code

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Why its important? 80% of the lifetime cost of a piece of software goes to maintenance. Hardly any software is maintained for its whole life by the original author. Code quality improve the readability of the software, allowing engineers to understand new code more quickly and thoroughly.

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Why do we see a bad code? Time: I don't have a time We never seem to have time to do it, but always seem find time to redo it?! Knowledge: what is a good code? Tools: I don’t know about it Skills: I can’t do it

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Naming is important

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The name should represent the developer’s idea

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The name should represent the developer’s idea

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The name should represent the developer’s idea

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Use meaningful difference

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Use meaningful names

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Use searchable names

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Class names

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Method names

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Method Names Should Say What They Do

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One function – one operation One function – one operation

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F1:Too Many Arguments F1:Too Many Arguments Functions should have a small number of arguments. No argument is best, followed by one, two, and three. F2: Output Arguments Output arguments are counterintuitive. Readers expect arguments to be inputs, not outputs. If your function must change the state of something, have it change the state of the object it is called on.

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F3: Flag Arguments F3: Flag Arguments Boolean arguments loudly declare that the function does more than one thing. They are confusing and should be eliminated F4: Dead Function Methods that are never called should be discarded. Keeping dead code around is wasteful. Don’t be afraid to delete the function. Remember, your source code control system still remembers it.

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Code review

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Comments C1: Inappropriate Information Change histories(?) Authors(?) Date of last update(?) C2: Obsolete Comment It is best not to write a comment that will become obsolete If you find an obsolete comments – update or erase it ASAP!

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Comments C3. Redundant Comment Don’t comment what a code does – I can read the code for that—keep it DRY Example 1 i++; // increment i What about example 2? /** * @param sellRequest * @return * @throws ManagedComponentException */ public SellResponse beginSellItem(SellRequest sellRequest) throws ManagedComponentException

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Comments C4: Poorly Written Comment Comments should say Why or purpose, not how C5: Commented-Out Code Who knows how old it is? Who knows whether or not it’s meaningful? Yet no one will delete it because everyone assumes someone else needs it or has plans for it.

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General G1: Multiple Languages in One Source File a Java source file might contain snippets of XML, HTML, YAML, JavaDoc, English, JavaScript or in addition to HTML a JSP file might contain Java, a tag library syntax, English comments, Javadocs, XML, JavaScript, and so forth. The ideal is for a source file to contain one, and only one, language. Realistically, we will probably have to use more than one.

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General G5: Duplication Every time you see duplication in the code, it represents a missed opportunity for abstraction. Result of copy/paste programming – to separate method switch/case or if/else chain that appears again and again in various modules, always testing for the same set of conditions – to use polymorphism

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General G5: Duplication (cont) modules that have similar algorithms, but that don’t share similar lines of code – to use Template Method or Strategy design patterns. Find and eliminate duplication wherever you can!

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General G6: Code at Wrong Level of Abstraction Good software design requires that we separate concepts at different levels and place them in different containers

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General G7: Base Classes Depending on Their Derivatives The most common reason for partitioning concepts into base and derivative classes is so that the higher level base class concepts can be independent of the lower level derivative class concepts.

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General G9: Dead Code You find it in the body of an if statement that checks for a condition that can’t happen. You find it in the catch block of a try that never throws. You find it in little utility methods that are never called or switch/case conditions that never occur.

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General G11: Inconsistency If you do something a certain way, do all similar things in the same way. If you name a method processVerificationRequest, then use a similar name, such as processDeletionRequest, for the methods that process other kinds of requests.

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General G23: Prefer Polymorphism to If/Else or Switch/Case “ONE SWITCH” rule: There may be no more than one switch statement for a given type of selection. The cases in that switch statement must create polymorphic objects that take the place of other such switch statements in the rest of the system.

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General G28: Encapsulate Conditionals if (shouldBeDeleted(timer)) is preferable to if (timer.hasExpired() && !timer.isRecurrent())

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General G29: Avoid Negative Conditionals if (buffer.shouldCompact()) is preferable to if (!buffer.shouldNotCompact())

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General G35: Keep Configurable Data at High Levels

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One more Clear, not Clever Don’t be clever, instead be clear “I never make stupid mistakes. Only very, very clever ones” John Peel

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What is “code smell”? Wiki say: In computer programming, code smell is any symptom in the source code of a program that possibly indicates a deeper problem. Code smells are usually not bugs—they are not technically incorrect and don't currently prevent the program from functioning. Instead, they indicate weaknesses in design that may be slowing down development or increasing the risk of bugs or failures in the future.

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The most “popular” code smells

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Bad vs. Clean code What is the clean code? What is the bad code? Characteristics of quality code Metrics to measure quality Ways to identify and build quality

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What do you know now? What is Code Smell It’s a feeling or sense that something is not right in the code You can’t understand it Hard to explain Does some magic Can we measure it?