src/site/articles/style-guide/index.markdown - Issue 118633004: New TOC for dart-by-example page

Unified Diff: src/site/articles/style-guide/index.markdown

Issue 118633004: New TOC for dart-by-example page (Closed) Base URL: https://github.com/dart-lang/dartlang.org.git@master

Patch Set: Merge Created 6 years, 11 months ago

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Index: src/site/articles/style-guide/index.markdown

diff --git a/src/site/articles/style-guide/index.markdown b/src/site/articles/style-guide/index.markdown

index f6413786206e9674a6c03f1b5d0f554a057071b6..0cd9da6566b58579574610a57c8a93831b4076d7 100644

--- a/src/site/articles/style-guide/index.markdown

+++ b/src/site/articles/style-guide/index.markdown

@@ -67,6 +67,7 @@ nice, readable and maintainable code.

## Types

#### AVOID creating classes that contain only static members.

+{:.no_toc}

In Java and C#, all members must be in a class. In those languages, you

occasionally encounter classes that are basically namespaces: just bags of

@@ -105,6 +106,7 @@ class GeometryUtils {

</div>

#### AVOID defining a one-member abstract class when a simple function will do.

+{:.no_toc}

Unlike Java, Dart has first-class functions, closures, and a nice light syntax

for using them. If all you need is something like a callback, just use a

@@ -129,6 +131,7 @@ abstract class Predicate {

## Members

#### DO use constructors instead of static methods to create instances.

+{:.no_toc}

Constructors are invoked using `new` or `const` which communicates clearly at

@@ -160,6 +163,7 @@ class Point {

</div>

#### DO use `;` instead of `{}` for empty constructor bodies.

+{:.no_toc}

In Dart, a constructor with an empty body can be terminated with just a

@@ -185,6 +189,7 @@ class Point {

</div>

#### DO place the `super()` call last in a constructor initialization list.

+{:.no_toc}

Field initializers are evaluated in the order that they appear in the

@@ -218,6 +223,7 @@ View(Style style, List children)

</div>

#### DO use a getter for operations that conceptually access a property.

+{:.no_toc}

If the name of the method starts with `get` or is an adjective like `visible` or

@@ -249,6 +255,7 @@ window.refresh; // doesn't return a value

</div>

#### DO use a setter for operations that conceptually change a property.

+{:.no_toc}

If the name of the method starts with `set` that's often a sign that it could be

@@ -271,6 +278,7 @@ button.visible = false;

</div>

#### AVOID wrapping fields in getters and setters just to be "safe".

+{:.no_toc}

In Java and C#, it's common to hide all fields behind getters and setters (or

@@ -305,6 +313,7 @@ class Box {

</div>

#### PREFER using a public final field instead of a private field with a public getter.

+{:.no_toc}

If you have a field that outside code should be able to see but not assign to

@@ -329,6 +338,7 @@ class Box {

</div>

#### CONSIDER using `=>` to define members whose body returns the result of a single expression.

+{:.no_toc}

In addition to using `=>` for function expressions, Dart also lets you define

@@ -348,6 +358,7 @@ cramming a single expression into several continued lines, it is probably

cleaner to just use a curly body with an explicit `return`.

#### AVOID boolean arguments unless their meaning is completely obvious.

+{:.no_toc}

Unlike other types, booleans are usually used in literal form. Things like

@@ -377,6 +388,7 @@ new ListBox(scroll: true, showScrollbars: true);

## Type annotations

#### PREFER providing type annotations on public APIs.

+{:.no_toc}

Type annotations are important documentation for how a library should be used.

@@ -412,6 +424,7 @@ Future<bool> install(PackageId id, String destPath) {

With types, all of this is clarified.

#### PREFER using `var` without a type annotation for local variables.

+{:.no_toc}

Method bodies in modern code tend to be short, and the types of local variables

@@ -447,6 +460,7 @@ Map<int, List<Person>> groupByZip(Iterable<Person> people) {

</div>

#### PREFER using `double` or `int` instead of `num` for parameter type annotations in performance sensitive code.

+{:.no_toc}

Monomorphic call sites (sites that have stable input types)

can be optimized much easier than polymorphic call sites (sites that have

@@ -460,6 +474,7 @@ When you use `num` as a type annotation, you are saying "either an int or

a double can go here." This ambiguity it harder for Dart runtimes to optimize.

#### DON'T type annotate initializing formals.

+{:.no_toc}

If a constructor parameter is using `this.` to initialize a field, then the type

@@ -484,6 +499,7 @@ class Point {

</div>

#### AVOID annotating types on function expressions.

+{:.no_toc}

The value of function expressions is their brevity. If a function is complex

@@ -506,6 +522,7 @@ var names = people.map((Person person) {

</div>

#### AVOID annotating with `dynamic` when not required.

+{:.no_toc}

In most places in Dart, a type annotation can be omitted, in which case the type

@@ -533,6 +550,7 @@ dynamic lookUpOrDefault(String name, Map map, dynamic defaultValue) {

</div>

#### DO annotate with `Object` instead of `dynamic` to indicate any object is accepted.

+{:.no_toc}

Some operations will work with any possible object. For example, a log method

@@ -565,6 +583,7 @@ bool convertToBool(arg) {

## Names

#### DO name types using `UpperCamelCase`.

+{:.no_toc}

Classes and typedefs should capitalize the first letter of each word (including

@@ -585,6 +604,7 @@ typedef num Adder(num x, num y);

</div>

#### DO name constants using `ALL_CAPS_WITH_UNDERSCORES`.

+{:.no_toc}

Constants—variables declared using `const`—are special in Dart

@@ -616,6 +636,7 @@ class Dice {

</div>

#### DO name other identifiers using `lowerCamelCase`.

+{:.no_toc}

Class members, top-level definitions, variables, parameters, and named

@@ -635,6 +656,7 @@ align(clearItems) {

</div>

#### DO name libraries and source files using `lowercase_with_underscores`.

+{:.no_toc}

Some file systems are not case-sensitive, so many projects require filenames to

@@ -660,6 +682,7 @@ Bad:

</div>

#### DO capitalize acronyms and abbreviations longer than two letters like words.

+{:.no_toc}

Capitalized acronyms can be harder to read, and are ambiguous when you have

@@ -693,6 +716,7 @@ Id

## Comments

#### DO comment members and types using doc-style comments.

+{:.no_toc}

Dart supports two syntaxes of doc comments. Line doc comments start each line

@@ -729,6 +753,7 @@ Within a doc comment, you can use [markdown][] for formatting.

[markdown]: http://daringfireball.net/projects/markdown/

#### DO use line comments for everything else.

+{:.no_toc}

@@ -750,6 +775,7 @@ greet(name) {

</div>

#### DO capitalize and punctuate comments like sentences.

+{:.no_toc}

This doesn't mean that the comment must always be a complete sentence, though it

@@ -768,6 +794,7 @@ usually should. "Returns the number of items." is an acceptable comment.

</div>

#### DO use square brackets in doc comments for identifiers that are in scope.

+{:.no_toc}

If you surround things like variable, method or type names in square brackets,

@@ -784,6 +811,7 @@ num greatestRoll(Dice a, Dice b) => max(a.roll(), b.roll());

</div>

#### DO describe method signatures in the prose of the documentation comment.

+{:.no_toc}

@@ -830,6 +858,7 @@ consistent whitespace style helps ensure that human readers see code the same

way the compiler does.

#### DON'T use tabs.

+{:.no_toc}

Using spaces for formatting ensures the code looks the same in everyone's

@@ -843,6 +872,7 @@ Modern editors emulate the behavior of tabs while inserting spaces, giving you

the easy editing of tabs and the consistency of spaces.

#### AVOID lines longer than 80 characters.

+{:.no_toc}

Readability studies show that long lines of text are harder to read because your

@@ -855,6 +885,7 @@ compact. Do you really need to call that class

`AbstractWidgetFactoryManagerBuilder`?

#### DO place the operator on the preceding line in a multi-line expression.

+{:.no_toc}

There are valid arguments for both styles but most of our code seems to go this

@@ -887,6 +918,7 @@ bobLikes()

</div>

#### DO place the `.` on the next line in a multi-line expression.

+{:.no_toc}

This supercedes the previous rule. Unlike other operators, if you split an

@@ -900,6 +932,7 @@ someVeryLongVariable.withAVeryLongProperty

</div>

#### DO indent block bodies two spaces.

+{:.no_toc}

@@ -911,6 +944,7 @@ if (condition) {

</div>

#### DO indent continued lines with at least four spaces.

+{:.no_toc}

@@ -930,6 +964,7 @@ someLongObject.aReallyLongMethodName(longArg, anotherLongArg,

</div>

#### DON'T indent lines that are continued with a function expression.

+{:.no_toc}

The one exception to the above rule is function expressions used within larger

@@ -952,6 +987,7 @@ new Future.delayed(const Duration(seconds: 1), () {

</div>

#### DO place the opening curly brace (`{`) on the same line as what it follows.

+{:.no_toc}

@@ -969,6 +1005,7 @@ class Foo {

</div>

#### DO use curly braces for all flow control structures.

+{:.no_toc}

Doing so avoids the [dangling else][] problem.

@@ -1003,6 +1040,7 @@ if (arg == null) return defaultValue;

</div>

#### DO indent switch cases two spaces and case bodies four spaces.

+{:.no_toc}

@@ -1020,6 +1058,7 @@ switch (fruit) {

</div>

#### DO use spaces around binary and ternary operators, after commas, and not around unary operators.

+{:.no_toc}

@@ -1047,6 +1086,7 @@ if (obj is !SomeType) print('not SomeType');

</div>

#### DO place spaces around `in`, and after each `;` in a loop.

+{:.no_toc}

@@ -1062,6 +1102,7 @@ for (final item in collection) {

</div>

#### DO use a space after flow-control keywords.

+{:.no_toc}

This is unlike function and method calls, which do *not* have a space between

@@ -1082,6 +1123,7 @@ try {

</div>

#### DON'T use a space after `(`, `[`, and `{`, or before `)`, `]`, and `}`.

+{:.no_toc}

Also, do not use a space when using `<` and `>` for generic types.

@@ -1093,6 +1135,7 @@ var numbers = <int>[1, 2, (3 + 4)];

</div>

#### DO use a space before `{` in function and method bodies.

+{:.no_toc}

This is an exception to the above rule. When a `{` is used after a parameter

@@ -1116,6 +1159,7 @@ getEmptyFn(a){

</div>

#### DO format constructor initialization lists with each field on its own line.

+{:.no_toc}

@@ -1134,6 +1178,7 @@ Fields should all line up (so all but the first field end up indented six

spaces).

#### DO use a space after `:` in named parameters and named arguments.

+{:.no_toc}

@@ -1158,6 +1203,7 @@ new ListBox(showScrollbars : true);

</div>

#### DO use a spaces around `=` in optional positional parameters.

+{:.no_toc}

@@ -1183,20 +1229,21 @@ class HttpServer {

</div>

#### DO use four spaces for method cascades

+{:.no_toc}

{% prettify dart %}

var list = new List()

- ..addAll([1,2,3])

- ..addAll([4,5,6]);

+ ..addAll([1, 2, 3])

+ ..addAll([4, 5, 6]);

{% endprettify %}

</div>

{% prettify dart %}

var list = new List()

- ..addAll([1,2,3])

- ..addAll([4,5,6]);

+ ..addAll([1, 2, 3])

+ ..addAll([4, 5, 6]);

{% endprettify %}

</div>

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