-
Notifications
You must be signed in to change notification settings - Fork 2
/
Copy pathapi_documentation_guidelines.html
508 lines (470 loc) · 30.8 KB
/
api_documentation_guidelines.html
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="zh-CN" lang="zh-CN">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8"/>
<meta name="viewport" content="width=device-width, initial-scale=1"/>
<title>API Documentation Guidelines — Ruby on Rails 指南</title>
<link rel="stylesheet" type="text/css" href="stylesheets/style.css" />
<link rel="stylesheet" type="text/css" href="stylesheets/print.css" media="print" />
<link rel="stylesheet" type="text/css" href="stylesheets/syntaxhighlighter/shCore.css" />
<link rel="stylesheet" type="text/css" href="stylesheets/syntaxhighlighter/shThemeRailsGuides.css" />
<link rel="stylesheet" type="text/css" href="stylesheets/fixes.css" />
<link href="images/favicon.ico" rel="shortcut icon" type="image/x-icon" />
</head>
<body class="guide">
<div id="topNav">
<div class="wrapper">
<strong class="more-info-label">更多内容 <a href="http://rubyonrails.org/">rubyonrails.org:</a> </strong>
<span class="red-button more-info-button">
更多内容
</span>
<ul class="more-info-links s-hidden">
<li class="more-info"><a href="http://rubyonrails.org/">综览</a></li>
<li class="more-info"><a href="http://rubyonrails.org/download">下载</a></li>
<li class="more-info"><a href="http://rubyonrails.org/deploy">部署</a></li>
<li class="more-info"><a href="https://github.com/rails/rails">源码</a></li>
<li class="more-info"><a href="http://rubyonrails.org/screencasts">视频</a></li>
<li class="more-info"><a href="http://rubyonrails.org/documentation">文件</a></li>
<li class="more-info"><a href="http://rubyonrails.org/community">社群</a></li>
<li class="more-info"><a href="http://weblog.rubyonrails.org/">Blog</a></li>
</ul>
</div>
</div>
<div id="header">
<div class="wrapper clearfix">
<h1><a href="index.html" title="回首页">Guides.rubyonrails.org</a></h1>
<ul class="nav">
<li><a class="nav-item" href="index.html">首页</a></li>
<li class="guides-index guides-index-large">
<a href="index.html" id="guidesMenu" class="guides-index-item nav-item">指南目录</a>
<div id="guides" class="clearfix" style="display: none;">
<hr />
<dl class="L">
<dt>入门</dt>
<dd><a href="getting_started.html">Rails 入门</a></dd>
<dt>模型</dt>
<dd><a href="active_record_basics.html">Active Record 基础</a></dd>
<dd><a href="active_record_migrations.html">Active Record 数据库迁移</a></dd>
<dd><a href="active_record_validations.html">Active Record 数据验证</a></dd>
<dd><a href="active_record_callbacks.html">Active Record 回调</a></dd>
<dd><a href="association_basics.html">Active Record 关联</a></dd>
<dd><a href="active_record_querying.html">Active Record 查询</a></dd>
<dt>视图</dt>
<dd><a href="layouts_and_rendering.html">Rails 布局和视图渲染</a></dd>
<dd><a href="form_helpers.html">Action View 表单帮助方法</a></dd>
<dt>控制器</dt>
<dd><a href="action_controller_overview.html">Action Controller 简介</a></dd>
<dd><a href="routing.html">Rails 路由全解</a></dd>
</dl>
<dl class="R">
<dt>深入</dt>
<dd><a href="active_support_core_extensions.html">Active Support 核心扩展</a></dd>
<dd><a href="i18n.html">Rails 国际化 API</a></dd>
<dd><a href="action_mailer_basics.html">Action Mailer 基础</a></dd>
<dd><a href="active_job_basics.html">Active Job 基础</a></dd>
<dd><a href="security.html">Rails 安全指南</a></dd>
<dd><a href="debugging_rails_applications.html">调试 Rails 程序</a></dd>
<dd><a href="configuring.html">设置 Rails 程序</a></dd>
<dd><a href="command_line.html">Rails 命令行</a></dd>
<dd><a href="asset_pipeline.html">Asset Pipeline</a></dd>
<dd><a href="working_with_javascript_in_rails.html">在 Rails 中使用 JavaScript</a></dd>
<dd><a href="constant_autoloading_and_reloading.html">Constant Autoloading and Reloading</a></dd>
<dt>扩展 Rails</dt>
<dd><a href="rails_on_rack.html">Rails on Rack</a></dd>
<dd><a href="generators.html">客制与新建 Rails 产生器</a></dd>
<dd><a href="rails_application_templates.html">Rails 应用程式模版</a></dd>
<dt>贡献 Ruby on Rails</dt>
<dd><a href="contributing_to_ruby_on_rails.html">贡献 Ruby on Rails</a></dd>
<dd><a href="api_documentation_guidelines.html">API 文件准则</a></dd>
<dd><a href="ruby_on_rails_guides_guidelines.html">Ruby on Rails 指南准则</a></dd>
<dt>维护方针</dt>
<dd><a href="maintenance_policy.html">维护方针</a></dd>
<dt>发布记</dt>
<dd><a href="upgrading_ruby_on_rails.html">升级 Ruby on Rails</a></dd>
<dd><a href="4_2_release_notes.html">Ruby on Rails 4.2 发布记</a></dd>
<dd><a href="4_1_release_notes.html">Ruby on Rails 4.1 发布记</a></dd>
<dd><a href="4_0_release_notes.html">Ruby on Rails 4.0 发布记</a></dd>
<dd><a href="3_2_release_notes.html">Ruby on Rails 3.2 发布记</a></dd>
<dd><a href="3_1_release_notes.html">Ruby on Rails 3.1 发布记</a></dd>
<dd><a href="3_0_release_notes.html">Ruby on Rails 3.0 发布记</a></dd>
<dd><a href="2_3_release_notes.html">Ruby on Rails 2.3 发布记</a></dd>
<dd><a href="2_2_release_notes.html">Ruby on Rails 2.2 发布记</a></dd>
</dl>
</div>
</li>
<!-- <li><a class="nav-item" href="//github.com/docrails-tw/wiki">参与翻译</a></li> -->
<li><a class="nav-item" href="https://github.com/ruby-china/guides/blob/master/CONTRIBUTING.md">贡献</a></li>
<li><a class="nav-item" href="credits.html">致谢</a></li>
<li class="guides-index guides-index-small">
<select class="guides-index-item nav-item">
<option value="index.html">指南目录</option>
<optgroup label="入门">
<option value="getting_started.html">Rails 入门</option>
</optgroup>
<optgroup label="模型">
<option value="active_record_basics.html">Active Record 基础</option>
<option value="active_record_migrations.html">Active Record 数据库迁移</option>
<option value="active_record_validations.html">Active Record 数据验证</option>
<option value="active_record_callbacks.html">Active Record 回调</option>
<option value="association_basics.html">Active Record 关联</option>
<option value="active_record_querying.html">Active Record 查询</option>
</optgroup>
<optgroup label="视图">
<option value="layouts_and_rendering.html">Rails 布局和视图渲染</option>
<option value="form_helpers.html">Action View 表单帮助方法</option>
</optgroup>
<optgroup label="控制器">
<option value="action_controller_overview.html">Action Controller 简介</option>
<option value="routing.html">Rails 路由全解</option>
</optgroup>
<optgroup label="深入">
<option value="active_support_core_extensions.html">Active Support 核心扩展</option>
<option value="i18n.html">Rails 国际化 API</option>
<option value="action_mailer_basics.html">Action Mailer 基础</option>
<option value="active_job_basics.html">Active Job 基础</option>
<option value="security.html">Rails 安全指南</option>
<option value="debugging_rails_applications.html">调试 Rails 程序</option>
<option value="configuring.html">设置 Rails 程序</option>
<option value="command_line.html">Rails 命令行</option>
<option value="asset_pipeline.html">Asset Pipeline</option>
<option value="working_with_javascript_in_rails.html">在 Rails 中使用 JavaScript</option>
<option value="constant_autoloading_and_reloading.html">Constant Autoloading and Reloading</option>
</optgroup>
<optgroup label="扩展 Rails">
<option value="rails_on_rack.html">Rails on Rack</option>
<option value="generators.html">客制与新建 Rails 产生器</option>
<option value="rails_application_templates.html">Rails 应用程式模版</option>
</optgroup>
<optgroup label="贡献 Ruby on Rails">
<option value="contributing_to_ruby_on_rails.html">贡献 Ruby on Rails</option>
<option value="api_documentation_guidelines.html">API 文件准则</option>
<option value="ruby_on_rails_guides_guidelines.html">Ruby on Rails 指南准则</option>
</optgroup>
<optgroup label="维护方针">
<option value="maintenance_policy.html">维护方针</option>
</optgroup>
<optgroup label="发布记">
<option value="upgrading_ruby_on_rails.html">升级 Ruby on Rails</option>
<option value="4_2_release_notes.html">Ruby on Rails 4.2 发布记</option>
<option value="4_1_release_notes.html">Ruby on Rails 4.1 发布记</option>
<option value="4_0_release_notes.html">Ruby on Rails 4.0 发布记</option>
<option value="3_2_release_notes.html">Ruby on Rails 3.2 发布记</option>
<option value="3_1_release_notes.html">Ruby on Rails 3.1 发布记</option>
<option value="3_0_release_notes.html">Ruby on Rails 3.0 发布记</option>
<option value="2_3_release_notes.html">Ruby on Rails 2.3 发布记</option>
<option value="2_2_release_notes.html">Ruby on Rails 2.2 发布记</option>
</optgroup>
</select>
</li>
</ul>
</div>
</div>
</div>
<hr class="hide" />
<div id="feature">
<div class="wrapper">
<h2>API Documentation Guidelines</h2><p>This guide documents the Ruby on Rails API documentation guidelines.</p><p>After reading this guide, you will know:</p>
<ul>
<li>How to write effective prose for documentation purposes.</li>
<li>Style guidelines for documenting different kinds of Ruby code.</li>
</ul>
<div id="subCol">
<h3 class="chapter"><img src="images/chapters_icon.gif" alt="" />Chapters</h3>
<ol class="chapters">
<li><a href="#rdoc">RDoc</a></li>
<li><a href="#wording">Wording</a></li>
<li><a href="#english">English</a></li>
<li><a href="#example-code">Example Code</a></li>
<li><a href="#booleans">Booleans</a></li>
<li><a href="#file-names">File Names</a></li>
<li>
<a href="#fonts">Fonts</a>
<ul>
<li><a href="#fixed-width-font">Fixed-width Font</a></li>
<li><a href="#regular-font">Regular Font</a></li>
</ul>
</li>
<li><a href="#description-lists">Description Lists</a></li>
<li><a href="#dynamically-generated-methods">Dynamically Generated Methods</a></li>
<li><a href="#method-visibility">Method Visibility</a></li>
<li><a href="#regarding-the-rails-stack">Regarding the Rails Stack</a></li>
</ol>
</div>
</div>
</div>
<div id="container">
<div class="wrapper">
<div id="mainCol">
<h3 id="rdoc">1 RDoc</h3><p>The <a href="http://api.rubyonrails.org">Rails API documentation</a> is generated with
<a href="http://docs.seattlerb.org/rdoc/">RDoc</a>.</p><div class="code_container">
<pre class="brush: plain; gutter: false; toolbar: false">
bundle exec rake rdoc
</pre>
</div>
<p>Resulting HTML files can be found in the ./doc/rdoc directory.</p><p>Please consult the RDoc documentation for help with the
<a href="http://docs.seattlerb.org/rdoc/RDoc/Markup.html">markup</a>,
and also take into account these <a href="http://docs.seattlerb.org/rdoc/RDoc/Parser/Ruby.html">additional
directives</a>.</p><h3 id="wording">2 Wording</h3><p>Write simple, declarative sentences. Brevity is a plus: get to the point.</p><p>Write in present tense: "Returns a hash that...", rather than "Returned a hash that..." or "Will return a hash that...".</p><p>Start comments in upper case. Follow regular punctuation rules:</p><div class="code_container">
<pre class="brush: ruby; gutter: false; toolbar: false">
# Declares an attribute reader backed by an internally-named
# instance variable.
def attr_internal_reader(*attrs)
...
end
</pre>
</div>
<p>Communicate to the reader the current way of doing things, both explicitly and implicitly. Use the idioms recommended in edge. Reorder sections to emphasize favored approaches if needed, etc. The documentation should be a model for best practices and canonical, modern Rails usage.</p><p>Documentation has to be concise but comprehensive. Explore and document edge cases. What happens if a module is anonymous? What if a collection is empty? What if an argument is nil?</p><p>The proper names of Rails components have a space in between the words, like "Active Support". <code>ActiveRecord</code> is a Ruby module, whereas Active Record is an ORM. All Rails documentation should consistently refer to Rails components by their proper name, and if in your next blog post or presentation you remember this tidbit and take it into account that'd be phenomenal.</p><p>Spell names correctly: Arel, Test::Unit, RSpec, HTML, MySQL, JavaScript, ERB. When in doubt, please have a look at some authoritative source like their official documentation.</p><p>Use the article "an" for "SQL", as in "an SQL statement". Also "an SQLite database".</p><p>Prefer wordings that avoid "you"s and "your"s. For example, instead of</p><div class="code_container">
<pre class="brush: plain; gutter: false; toolbar: false">
If you need to use `return` statements in your callbacks, it is recommended that you explicitly define them as methods.
</pre>
</div>
<p>use this style:</p><div class="code_container">
<pre class="brush: plain; gutter: false; toolbar: false">
If `return` is needed it is recommended to explicitly define a method.
</pre>
</div>
<p>That said, when using pronouns in reference to a hypothetical person, such as "a
user with a session cookie", gender neutral pronouns (they/their/them) should be
used. Instead of:</p>
<ul>
<li>he or she... use they.</li>
<li>him or her... use them.</li>
<li>his or her... use their.</li>
<li>his or hers... use theirs.</li>
<li>himself or herself... use themselves.</li>
</ul>
<h3 id="english">3 English</h3><p>Please use American English (<em>color</em>, <em>center</em>, <em>modularize</em>, etc). See <a href="http://en.wikipedia.org/wiki/American_and_British_English_spelling_differences">a list of American and British English spelling differences here</a>.</p><h3 id="example-code">4 Example Code</h3><p>Choose meaningful examples that depict and cover the basics as well as interesting points or gotchas.</p><p>Use two spaces to indent chunks of code--that is, for markup purposes, two spaces with respect to the left margin. The examples themselves should use <a href="contributing_to_ruby_on_rails.html#follow-the-coding-conventions">Rails coding conventions</a>.</p><p>Short docs do not need an explicit "Examples" label to introduce snippets; they just follow paragraphs:</p><div class="code_container">
<pre class="brush: ruby; gutter: false; toolbar: false">
# Converts a collection of elements into a formatted string by
# calling +to_s+ on all elements and joining them.
#
# Blog.all.to_formatted_s # => "First PostSecond PostThird Post"
</pre>
</div>
<p>On the other hand, big chunks of structured documentation may have a separate "Examples" section:</p><div class="code_container">
<pre class="brush: ruby; gutter: false; toolbar: false">
# ==== Examples
#
# Person.exists?(5)
# Person.exists?('5')
# Person.exists?(name: "David")
# Person.exists?(['name LIKE ?', "%#{query}%"])
</pre>
</div>
<p>The results of expressions follow them and are introduced by "# => ", vertically aligned:</p><div class="code_container">
<pre class="brush: ruby; gutter: false; toolbar: false">
# For checking if a fixnum is even or odd.
#
# 1.even? # => false
# 1.odd? # => true
# 2.even? # => true
# 2.odd? # => false
</pre>
</div>
<p>If a line is too long, the comment may be placed on the next line:</p><div class="code_container">
<pre class="brush: ruby; gutter: false; toolbar: false">
# label(:article, :title)
# # => <label for="article_title">Title</label>
#
# label(:article, :title, "A short title")
# # => <label for="article_title">A short title</label>
#
# label(:article, :title, "A short title", class: "title_label")
# # => <label for="article_title" class="title_label">A short title</label>
</pre>
</div>
<p>Avoid using any printing methods like <code>puts</code> or <code>p</code> for that purpose.</p><p>On the other hand, regular comments do not use an arrow:</p><div class="code_container">
<pre class="brush: ruby; gutter: false; toolbar: false">
# polymorphic_url(record) # same as comment_url(record)
</pre>
</div>
<h3 id="booleans">5 Booleans</h3><p>In predicates and flags prefer documenting boolean semantics over exact values.</p><p>When "true" or "false" are used as defined in Ruby use regular font. The
singletons <code>true</code> and <code>false</code> need fixed-width font. Please avoid terms like
"truthy", Ruby defines what is true and false in the language, and thus those
words have a technical meaning and need no substitutes.</p><p>As a rule of thumb, do not document singletons unless absolutely necessary. That
prevents artificial constructs like <code>!!</code> or ternaries, allows refactors, and the
code does not need to rely on the exact values returned by methods being called
in the implementation.</p><p>For example:</p><div class="code_container">
<pre class="brush: plain; gutter: false; toolbar: false">
`config.action_mailer.perform_deliveries` specifies whether mail will actually be delivered and is true by default
</pre>
</div>
<p>the user does not need to know which is the actual default value of the flag,
and so we only document its boolean semantics.</p><p>An example with a predicate:</p><div class="code_container">
<pre class="brush: ruby; gutter: false; toolbar: false">
# Returns true if the collection is empty.
#
# If the collection has been loaded
# it is equivalent to <tt>collection.size.zero?</tt>. If the
# collection has not been loaded, it is equivalent to
# <tt>collection.exists?</tt>. If the collection has not already been
# loaded and you are going to fetch the records anyway it is better to
# check <tt>collection.length.zero?</tt>.
def empty?
if loaded?
size.zero?
else
@target.blank? && !scope.exists?
end
end
</pre>
</div>
<p>The API is careful not to commit to any particular value, the method has
predicate semantics, that's enough.</p><h3 id="file-names">6 File Names</h3><p>As a rule of thumb, use filenames relative to the application root:</p><div class="code_container">
<pre class="brush: plain; gutter: false; toolbar: false">
config/routes.rb # YES
routes.rb # NO
RAILS_ROOT/config/routes.rb # NO
</pre>
</div>
<h3 id="fonts">7 Fonts</h3><h4 id="fixed-width-font">7.1 Fixed-width Font</h4><p>Use fixed-width fonts for:</p>
<ul>
<li>Constants, in particular class and module names.</li>
<li>Method names.</li>
<li>Literals like <code>nil</code>, <code>false</code>, <code>true</code>, <code>self</code>.</li>
<li>Symbols.</li>
<li>Method parameters.</li>
<li>File names.</li>
</ul>
<div class="code_container">
<pre class="brush: ruby; gutter: false; toolbar: false">
class Array
# Calls +to_param+ on all its elements and joins the result with
# slashes. This is used by +url_for+ in Action Pack.
def to_param
collect { |e| e.to_param }.join '/'
end
end
</pre>
</div>
<div class="warning"><p>Using <code>+...+</code> for fixed-width font only works with simple content like
ordinary method names, symbols, paths (with forward slashes), etc. Please use
<code><tt>...</tt></code> for everything else, notably class or module names with a
namespace as in <code><tt>ActiveRecord::Base</tt></code>.</p></div><p>You can quickly test the RDoc output with the following command:</p><div class="code_container">
<pre class="brush: plain; gutter: false; toolbar: false">
$ echo "+:to_param+" | rdoc --pipe
#=> <p><code>:to_param</code></p>
</pre>
</div>
<h4 id="regular-font">7.2 Regular Font</h4><p>When "true" and "false" are English words rather than Ruby keywords use a regular font:</p><div class="code_container">
<pre class="brush: ruby; gutter: false; toolbar: false">
# Runs all the validations within the specified context.
# Returns true if no errors are found, false otherwise.
#
# If the argument is false (default is +nil+), the context is
# set to <tt>:create</tt> if <tt>new_record?</tt> is true,
# and to <tt>:update</tt> if it is not.
#
# Validations with no <tt>:on</tt> option will run no
# matter the context. Validations with # some <tt>:on</tt>
# option will only run in the specified context.
def valid?(context = nil)
...
end
</pre>
</div>
<h3 id="description-lists">8 Description Lists</h3><p>In lists of options, parameters, etc. use a hyphen between the item and its description (reads better than a colon because normally options are symbols):</p><div class="code_container">
<pre class="brush: ruby; gutter: false; toolbar: false">
# * <tt>:allow_nil</tt> - Skip validation if attribute is +nil+.
</pre>
</div>
<p>The description starts in upper case and ends with a full stop-it's standard English.</p><h3 id="dynamically-generated-methods">9 Dynamically Generated Methods</h3><p>Methods created with <code>(module|class)_eval(STRING)</code> have a comment by their side with an instance of the generated code. That comment is 2 spaces away from the template:</p><div class="code_container">
<pre class="brush: ruby; gutter: false; toolbar: false">
for severity in Severity.constants
class_eval <<-EOT, __FILE__, __LINE__
def #{severity.downcase}(message = nil, progname = nil, &block) # def debug(message = nil, progname = nil, &block)
add(#{severity}, message, progname, &block) # add(DEBUG, message, progname, &block)
end # end
#
def #{severity.downcase}? # def debug?
#{severity} >= @level # DEBUG >= @level
end # end
EOT
end
</pre>
</div>
<p>If the resulting lines are too wide, say 200 columns or more, put the comment above the call:</p><div class="code_container">
<pre class="brush: ruby; gutter: false; toolbar: false">
# def self.find_by_login_and_activated(*args)
# options = args.extract_options!
# ...
# end
self.class_eval %{
def self.#{method_id}(*args)
options = args.extract_options!
...
end
}
</pre>
</div>
<h3 id="method-visibility">10 Method Visibility</h3><p>When writing documentation for Rails, it's important to understand the difference between public user-facing API vs internal API.</p><p>Rails, like most libraries, uses the private keyword from Ruby for defining internal API. However, public API follows a slightly different convention. Instead of assuming all public methods are designed for user consumption, Rails uses the <code>:nodoc:</code> directive to annotate these kinds of methods as internal API.</p><p>This means that there are methods in Rails with <code>public</code> visibility that aren't meant for user consumption.</p><p>An example of this is <code>ActiveRecord::Core::ClassMethods#arel_table</code>:</p><div class="code_container">
<pre class="brush: ruby; gutter: false; toolbar: false">
module ActiveRecord::Core::ClassMethods
def arel_table #:nodoc:
# do some magic..
end
end
</pre>
</div>
<p>If you thought, "this method looks like a public class method for <code>ActiveRecord::Core</code>", you were right. But actually the Rails team doesn't want users to rely on this method. So they mark it as <code>:nodoc:</code> and it's removed from public documentation. The reasoning behind this is to allow the team to change these methods according to their internal needs across releases as they see fit. The name of this method could change, or the return value, or this entire class may disappear; there's no guarantee and so you shouldn't depend on this API in your plugins or applications. Otherwise, you risk your app or gem breaking when you upgrade to a newer release of Rails.</p><p>As a contributor, it's important to think about whether this API is meant for end-user consumption. The Rails team is committed to not making any breaking changes to public API across releases without going through a full deprecation cycle. It's recommended that you <code>:nodoc:</code> any of your internal methods/classes unless they're already private (meaning visibility), in which case it's internal by default. Once the API stabilizes the visibility can change, but changing public API is much harder due to backwards compatibility.</p><p>A class or module is marked with <code>:nodoc:</code> to indicate that all methods are internal API and should never be used directly.</p><p>If you come across an existing <code>:nodoc:</code> you should tread lightly. Consider asking someone from the core team or author of the code before removing it. This should almost always happen through a pull request instead of the docrails project.</p><p>A <code>:nodoc:</code> should never be added simply because a method or class is missing documentation. There may be an instance where an internal public method wasn't given a <code>:nodoc:</code> by mistake, for example when switching a method from private to public visibility. When this happens it should be discussed over a PR on a case-by-case basis and never committed directly to docrails.</p><p>To summarize, the Rails team uses <code>:nodoc:</code> to mark publicly visible methods and classes for internal use; changes to the visibility of API should be considered carefully and discussed over a pull request first.</p><h3 id="regarding-the-rails-stack">11 Regarding the Rails Stack</h3><p>When documenting parts of Rails API, it's important to remember all of the
pieces that go into the Rails stack.</p><p>This means that behavior may change depending on the scope or context of the
method or class you're trying to document.</p><p>In various places there is different behavior when you take the entire stack
into account, one such example is
<code>ActionView::Helpers::AssetTagHelper#image_tag</code>:</p><div class="code_container">
<pre class="brush: ruby; gutter: false; toolbar: false">
# image_tag("icon.png")
# # => <img alt="Icon" src="/assets/icon.png" />
</pre>
</div>
<p>Although the default behavior for <code>#image_tag</code> is to always return
<code>/images/icon.png</code>, we take into account the full Rails stack (including the
Asset Pipeline) we may see the result seen above.</p><p>We're only concerned with the behavior experienced when using the full default
Rails stack.</p><p>In this case, we want to document the behavior of the <em>framework</em>, and not just
this specific method.</p><p>If you have a question on how the Rails team handles certain API, don't hesitate to open a ticket or send a patch to the <a href="https://github.com/rails/rails/issues">issue tracker</a>.</p>
<h3>反馈</h3>
<p>
欢迎帮忙改善指南质量。
</p>
<p>
如发现任何错误，欢迎修正。开始贡献前，可先行阅读<a href="http://edgeguides.rubyonrails.org/contributing_to_ruby_on_rails.html#contributing-to-the-rails-documentation">贡献指南：文档</a>。
</p>
<p>翻译如有错误，深感抱歉，欢迎 <a href="https://github.com/ruby-china/guides/fork">Fork</a> 修正，或至此处<a href="https://github.com/ruby-china/guides/issues/new">回报</a>。</p>
<p>
文章可能有未完成或过时的内容。请先检查 <a href="http://edgeguides.rubyonrails.org">Edge Guides</a> 来确定问题在 master 是否已经修掉了。再上 master 补上缺少的文件。内容参考 <a href="ruby_on_rails_guides_guidelines.html">Ruby on Rails 指南准则</a>来了解行文风格。
</p>
<p>最后，任何关于 Ruby on Rails 文档的讨论，欢迎到 <a href="http://groups.google.com/group/rubyonrails-docs">rubyonrails-docs 邮件群组</a>。
</p>
</div>
</div>
</div>
<hr class="hide" />
<div id="footer">
<div class="wrapper">
<p>本著作采用<a href="https://creativecommons.org/licenses/by-sa/4.0/">创用 CC 姓名标示-相同方式分享 4.0 国际授权条款</a>授权。</p>
<p>“Rails”、“Ruby on Rails”，以及 Rails logo 为 David Heinemeier Hansson 的商标。版权所有。</p>
</div>
</div>
<script type="text/javascript" src="javascripts/jquery.min.js"></script>
<script type="text/javascript" src="javascripts/responsive-tables.js"></script>
<script type="text/javascript" src="javascripts/guides.js"></script>
<script type="text/javascript" src="javascripts/syntaxhighlighter/shCore.js"></script>
<script type="text/javascript" src="javascripts/syntaxhighlighter/shBrushRuby.js"></script>
<script type="text/javascript" src="javascripts/syntaxhighlighter/shBrushXml.js"></script>
<script type="text/javascript" src="javascripts/syntaxhighlighter/shBrushSql.js"></script>
<script type="text/javascript" src="javascripts/syntaxhighlighter/shBrushPlain.js"></script>
<script type="text/javascript">
SyntaxHighlighter.all();
$(guidesIndex.bind);
</script>
<script>
(function(i,s,o,g,r,a,m){i['GoogleAnalyticsObject']=r;i[r]=i[r]||function(){
(i[r].q=i[r].q||[]).push(arguments)},i[r].l=1*new Date();a=s.createElement(o),
m=s.getElementsByTagName(o)[0];a.async=1;a.src=g;m.parentNode.insertBefore(a,m)
})(window,document,'script','//www.google-analytics.com/analytics.js','ga');
// ga('create', '', 'ruby-china.github.io');
ga('require', 'displayfeatures');
ga('send', 'pageview');
</script>
</body>
</html>