Mind (Mind1949)

使用 rvm 安装 ruby 失败

Mind — Mon, 19 Mar 2018 11:27:19 +0800

命令：

rvm install 2.2.5

报错：

ruby-2.2.5 - #removing src/ruby-2.2.5 - please wait
Searching for binary rubies, this might take some time.
No binary rubies available for: osx/10.13/x86_64/ruby-2.2.5.
Continuing with compilation. Please read 'rvm help mount' to get more information on binary rubies.
Checking requirements for osx.
Certificates bundle '/usr/local/etc/openssl/cert.pem' is already up to date.
Requirements installation successful.
Installing Ruby from source to: /Users/mind1949/.rvm/rubies/ruby-2.2.5, this may take a while depending on your cpu(s)...
ruby-2.2.5 - #downloading ruby-2.2.5, this may take a while depending on your connection...
ruby-2.2.5 - #extracting ruby-2.2.5 to /Users/mind1949/.rvm/src/ruby-2.2.5 - please wait
ruby-2.2.5 - #applying patch /Users/mind1949.rvm/patches/ruby/2.2.5/openssl3.patch - please wait
ruby-2.2.5 - #configuring - please wait
ruby-2.2.5 - #post-configuration - please wait
ruby-2.2.5 - #compiling - please wait
Error running '__rvm_make -j 1',
please read /Users/mind1949/.rvm/log/1521429775_ruby-2.2.5/make.log
There has been an error while running make. Halting the installation.

vim /Users/mind1949/.rvm/log/1521429775_ruby-2.2.5/make.log

打印出内容：

+__rvm_make:0> make -j 1
        CC = gcc
        LD = ld
        LDSHARED = gcc -dynamiclib
        CFLAGS = -O3 -fno-fast-math -ggdb3 -Wall -Wextra -Wno-unused-parameter -Wno-parentheses -Wno-long-long -Wno-missing-field-initializers -Wunused-variable -Wpointer-arith -Wwrite-strings -Wdeclaration-after-statement -Wshorten-64-to-32 -Wimplicit-function-declaration -Wdivision-by-zero -Wdeprecated-declarations -Wextra-tokens   -fno-common -pipe
        XCFLAGS = -D_FORTIFY_SOURCE=2 -fstack-protector -fno-strict-overflow -fvisibility=hidden -DRUBY_EXPORT
        CPPFLAGS = -I/usr/local/opt/libyaml/include -I/usr/local/opt/readline/include -I/usr/local/opt/libksba/include -I/usr/local/opt/openssl/include -D_XOPEN_SOURCE -D_DARWIN_C_SOURCE -D_DARWIN_UNLIMITED_SELECT -D_REENTRANT   -I. -I.ext/include/x86_64-darwin17 -I./include -I.
        DLDFLAGS = -Wl,-undefined,dynamic_lookup -Wl,-multiply_defined,suppress -L/usr/local/opt/libyaml/lib -L/usr/local/opt/readline/lib -L/usr/local/opt/libksba/lib -L/usr/local/opt/openssl/lib  -install_name /Users/mind1949/.rvm/rubies/ruby-2.2.5/lib/libruby.2.2.0.dylib -current_version 2.2.0 -compatibility_version 2.2.0  -fstack-protector -Wl,-u,_objc_msgSend -framework CoreFoundation  -fstack-protector -Wl,-u,_objc_msgSend -framework CoreFoundation
        SOLIBS = -lpthread -ldl -lobjc
Configured with: --prefix=/Applications/Xcode.app/Contents/Developer/usr --with-gxx-include-dir=/usr/include/c++/4.2.1
Apple LLVM version 9.0.0 (clang-900.0.39.2)
Target: x86_64-apple-darwin17.4.0
Thread model: posix
InstalledDir: /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin
translating probes probes.d
error: error reading '/dev/fd/4'
1 error generated.
clang: error: unable to remove file: Operation not permitted
dtrace: failed to compile script probes.d: Preprocessor failed to process input program
make: *** [probes.h] Error 1
+__rvm_make:0> return 2

用 js 遍历数组，然后调用 python 脚本处理数组元素，但得到的结果却是乱序的

Mind — Mon, 26 Feb 2018 11:28:07 +0800

1. 代码：

1.1 js 脚本

// call_py.js

// 制作数组
var s1="1 What makes Rails so great?"
var s2 = "2 do you love me still ?"
var s3 = "3 The Ruby on Rails Tutorial is designed to give you a thorough introduction to web application developmentntrepreneur."
var s4 = "4 of course i still love you . "
var list=[s1,s2,s3,s4]

// 子进程
var exec = require('child_process').exec;

//  遍历数组
let iterable = list

for(let value of iterable)
{
    exec('python py_test.py '+value+' ',function(error,stdout,stderr)
            {
                if(error){
                    console.log(stderr)
                }else{
                    console.log(stdout)
                }
            }

        )
}

1.2 python 脚本：

# py_test.py
import sys

script = sys.argv
print script

1.3 输出的结果：

['py_test.py', '1', 'What', 'makes', 'Rails', 'so', 'great?']

['py_test.py', '2', 'do', 'you', 'love', 'me', 'still', '?']

['py_test.py', '3', 'The', 'Ruby', 'on', 'Rails', 'Tutorial', 'is', 'designed', 'to', 'give', 'you', 'a', 'thorough', 'introduction', 'to', 'web', 'application', 'developmentntrepreneur.']

['py_test.py', '4', 'of', 'course', 'i', 'still', 'love', 'you', '.']

2.疑问：

2.1 问题一：

为什么输出的结果不是按照数组的顺序来的，而是乱序的？

怎样才能输出按照数组顺序的结果？

2.2 问题二：

因为我在 js 脚本的第 18 行用的是'python py_test.py '+value+' ',所以我觉得应该是将value作为一个值传递给 python 脚本，但是实际输出结果却显示是拆分成了很多个词，然后变成了很多个值？

学习 ruby on rails tutorial ,无法使用 aws 在生产环境中上传图片

Mind — Sat, 10 Feb 2018 16:43:39 +0800

求前辈帮忙🙏

按照 ruby on rails tutorila 的11.4.4: Image upload in production步骤，实作了在上产环境中上传图片的功能。

但是当实际使用时发现了下面的报错：

然后在终端运行：

heroku logs

产生如下 logs:

2018-02-10T08:36:22.160097+00:00 app[web.1]: I, [2018-02-10T08:36:22.160009 #6]  INFO -- : [b40b838f-613a-492a-b995-ee09f56c4443] Completed 200 OK in 20ms (Views: 11.8ms | ActiveRecord: 1.1ms)
2018-02-10T08:36:22.333445+00:00 heroku[router]: at=info method=GET path="/assets/rails-c094bc3a4bf50e5bb477109e5cb0d213af27ad75b481c4df249f50974dbeefe6.png" host=sample-app-180103.herokuapp.com request_id=aff85d8b-ef58-43ea-8e59-14c1d54fdadb fwd="54.167.204.162,66.102.7.132" dyno=web.1 connect=1ms service=3ms status=200 bytes=13232 protocol=https
2018-02-10T08:36:22.335622+00:00 heroku[router]: at=info method=GET path="/assets/application-30bba49027f3cb704192910ffbdb5f2e567bc29d091a86128f922104fbf13bf1.css" host=sample-app-180103.herokuapp.com request_id=255ae3e7-b419-415a-87c5-c985ba30195c fwd="54.167.204.162,66.102.7.135" dyno=web.1 connect=1ms service=10ms status=200 bytes=21197 protocol=https
2018-02-10T08:36:22.342813+00:00 heroku[router]: at=info method=GET path="/assets/application-ab447df98d0a8f179077b6934860dfcb7113a267fd726f9d9bd922d749f89f5d.js" host=sample-app-180103.herokuapp.com request_id=52e9676e-b94f-47ea-909f-798904de5c32 fwd="54.167.204.162,66.102.7.143" dyno=web.1 connect=1ms service=8ms status=200 bytes=57004 protocol=https
2018-02-10T08:36:22.523169+00:00 heroku[router]: at=info method=GET path="/" host=sample-app-180103.herokuapp.com request_id=48a07dcb-ab9f-4fa1-a721-ac885afb8a8c fwd="54.167.204.162,66.249.83.88" dyno=web.1 connect=0ms service=66ms status=200 bytes=2841 protocol=https
2018-02-10T08:36:22.614651+00:00 heroku[router]: at=info method=GET path="/favicon.ico" host=sample-app-180103.herokuapp.com request_id=c99b9cbe-b08d-46b4-9aa2-c9c6df595cca fwd="54.167.204.162,66.249.83.82" dyno=web.1 connect=0ms service=16ms status=200 bytes=207 protocol=https
2018-02-10T08:36:22.458263+00:00 app[web.1]: I, [2018-02-10T08:36:22.458156 #9]  INFO -- : [48a07dcb-ab9f-4fa1-a721-ac885afb8a8c] Started GET "/" for 66.249.83.88 at 2018-02-10 08:36:22 +0000
2018-02-10T08:36:22.459034+00:00 app[web.1]: I, [2018-02-10T08:36:22.458957 #9]  INFO -- : [48a07dcb-ab9f-4fa1-a721-ac885afb8a8c] Processing by StaticPagesController#home as HTML
2018-02-10T08:36:22.465205+00:00 app[web.1]: I, [2018-02-10T08:36:22.465096 #9]  INFO -- : [48a07dcb-ab9f-4fa1-a721-ac885afb8a8c]   Rendering static_pages/home.html.erb within layouts/application
2018-02-10T08:36:22.473361+00:00 app[web.1]: D, [2018-02-10T08:36:22.473229 #9] DEBUG -- : [48a07dcb-ab9f-4fa1-a721-ac885afb8a8c]   User Load (4.8ms)  SELECT  "users".* FROM "users" WHERE "users"."id" IS NULL LIMIT $1  [["LIMIT", 1]]
2018-02-10T08:36:22.475477+00:00 app[web.1]: I, [2018-02-10T08:36:22.475391 #9]  INFO -- : [48a07dcb-ab9f-4fa1-a721-ac885afb8a8c]   Rendered static_pages/_if_log_out_part.html.erb (0.9ms)
2018-02-10T08:36:22.475821+00:00 app[web.1]: I, [2018-02-10T08:36:22.475745 #9]  INFO -- : [48a07dcb-ab9f-4fa1-a721-ac885afb8a8c]   Rendered static_pages/home.html.erb within layouts/application (10.5ms)
2018-02-10T08:36:22.501860+00:00 app[web.1]: I, [2018-02-10T08:36:22.476721 #9]  INFO -- : [48a07dcb-ab9f-4fa1-a721-ac885afb8a8c]   Rendered layouts/_rails_default.html.erb (0.7ms)
2018-02-10T08:36:22.502318+00:00 app[web.1]: I, [2018-02-10T08:36:22.502215 #9]  INFO -- : [48a07dcb-ab9f-4fa1-a721-ac885afb8a8c]   Rendered layouts/_shim.html.erb (0.1ms)
2018-02-10T08:36:22.503848+00:00 app[web.1]: D, [2018-02-10T08:36:22.503765 #9] DEBUG -- : [48a07dcb-ab9f-4fa1-a721-ac885afb8a8c]   CACHE User Load (0.0ms)  SELECT  "users".* FROM "users" WHERE "users"."id" IS NULL LIMIT $1  [["LIMIT", 1]]
2018-02-10T08:36:22.504193+00:00 app[web.1]: I, [2018-02-10T08:36:22.504106 #9]  INFO -- : [48a07dcb-ab9f-4fa1-a721-ac885afb8a8c]   Rendered layouts/_header.html.erb (1.6ms)
2018-02-10T08:36:22.504697+00:00 app[web.1]: I, [2018-02-10T08:36:22.504624 #9]  INFO -- : [48a07dcb-ab9f-4fa1-a721-ac885afb8a8c]   Rendered layouts/_footer.html.erb (0.2ms)
2018-02-10T08:36:22.521500+00:00 app[web.1]: I, [2018-02-10T08:36:22.521327 #9]  INFO -- : [48a07dcb-ab9f-4fa1-a721-ac885afb8a8c] Completed 200 OK in 62ms (Views: 51.8ms | ActiveRecord: 4.8ms)
2018-02-10T08:36:31.959231+00:00 heroku[router]: at=info method=GET path="/" host=sample-app-180103.herokuapp.com request_id=009217a0-f248-4911-af84-a209bf3c141f fwd="54.167.204.162" dyno=web.1 connect=0ms service=21ms status=200 bytes=4452 protocol=https
2018-02-10T08:36:31.938403+00:00 app[web.1]: I, [2018-02-10T08:36:31.938312 #9]  INFO -- : [009217a0-f248-4911-af84-a209bf3c141f] Started GET "/" for 54.167.204.162 at 2018-02-10 08:36:31 +0000
2018-02-10T08:36:31.939194+00:00 app[web.1]: I, [2018-02-10T08:36:31.939114 #9]  INFO -- : [009217a0-f248-4911-af84-a209bf3c141f] Processing by StaticPagesController#home as HTML
2018-02-10T08:36:31.942044+00:00 app[web.1]: D, [2018-02-10T08:36:31.941925 #9] DEBUG -- : [009217a0-f248-4911-af84-a209bf3c141f]   User Load (0.8ms)  SELECT  "users".* FROM "users" WHERE "users"."id" = $1 LIMIT $2  [["id", 102], ["LIMIT", 1]]
2018-02-10T08:36:31.946500+00:00 app[web.1]: I, [2018-02-10T08:36:31.946397 #9]  INFO -- : [009217a0-f248-4911-af84-a209bf3c141f]   Rendering static_pages/home.html.erb within layouts/application
2018-02-10T08:36:31.949958+00:00 app[web.1]: D, [2018-02-10T08:36:31.949851 #9] DEBUG -- : [009217a0-f248-4911-af84-a209bf3c141f]    (1.1ms)  SELECT COUNT(*) FROM "microposts" WHERE "microposts"."user_id" = $1  [["user_id", 102]]
2018-02-10T08:36:31.950350+00:00 app[web.1]: I, [2018-02-10T08:36:31.950278 #9]  INFO -- : [009217a0-f248-4911-af84-a209bf3c141f]   Rendered shared/_user_info.html.erb (3.3ms)
2018-02-10T08:36:31.951116+00:00 app[web.1]: I, [2018-02-10T08:36:31.951041 #9]  INFO -- : [009217a0-f248-4911-af84-a209bf3c141f]   Rendered shared/_error_messages.html.erb (0.1ms)
2018-02-10T08:36:31.952187+00:00 app[web.1]: I, [2018-02-10T08:36:31.952115 #9]  INFO -- : [009217a0-f248-4911-af84-a209bf3c141f]   Rendered shared/_micropost_form.html.erb (1.6ms)
2018-02-10T08:36:31.953408+00:00 app[web.1]: D, [2018-02-10T08:36:31.953327 #9] DEBUG -- : [009217a0-f248-4911-af84-a209bf3c141f]   CACHE  (0.0ms)  SELECT COUNT(*) FROM "microposts" WHERE "microposts"."user_id" = $1  [["user_id", 102]]
2018-02-10T08:36:31.953621+00:00 app[web.1]: I, [2018-02-10T08:36:31.953544 #9]  INFO -- : [009217a0-f248-4911-af84-a209bf3c141f]   Rendered shared/_feed.html.erb (1.2ms)
2018-02-10T08:36:31.953780+00:00 app[web.1]: I, [2018-02-10T08:36:31.953713 #9]  INFO -- : [009217a0-f248-4911-af84-a209bf3c141f]   Rendered static_pages/_if_log_in_part.html.erb (6.9ms)
2018-02-10T08:36:31.953960+00:00 app[web.1]: I, [2018-02-10T08:36:31.953891 #9]  INFO -- : [009217a0-f248-4911-af84-a209bf3c141f]   Rendered static_pages/home.html.erb within layouts/application (7.2ms)
2018-02-10T08:36:31.954888+00:00 app[web.1]: I, [2018-02-10T08:36:31.954818 #9]  INFO -- : [009217a0-f248-4911-af84-a209bf3c141f]   Rendered layouts/_rails_default.html.erb (0.6ms)
2018-02-10T08:36:31.955217+00:00 app[web.1]: I, [2018-02-10T08:36:31.955145 #9]  INFO -- : [009217a0-f248-4911-af84-a209bf3c141f]   Rendered layouts/_shim.html.erb (0.1ms)
2018-02-10T08:36:31.956486+00:00 app[web.1]: I, [2018-02-10T08:36:31.956415 #9]  INFO -- : [009217a0-f248-4911-af84-a209bf3c141f]   Rendered layouts/_header.html.erb (1.0ms)
2018-02-10T08:36:31.957050+00:00 app[web.1]: I, [2018-02-10T08:36:31.956978 #9]  INFO -- : [009217a0-f248-4911-af84-a209bf3c141f]   Rendered layouts/_footer.html.erb (0.2ms)
2018-02-10T08:36:31.957417+00:00 app[web.1]: I, [2018-02-10T08:36:31.957348 #9]  INFO -- : [009217a0-f248-4911-af84-a209bf3c141f] Completed 200 OK in 18ms (Views: 10.2ms | ActiveRecord: 1.9ms)
2018-02-10T08:36:46.618182+00:00 heroku[router]: at=info method=POST path="/microposts" host=sample-app-180103.herokuapp.com request_id=7c09f6c8-adf5-4eea-b5b3-6f8d216881c5 fwd="54.167.204.162" dyno=web.1 connect=0ms service=16ms status=302 bytes=1013 protocol=https
2018-02-10T08:36:46.604722+00:00 app[web.1]: I, [2018-02-10T08:36:46.604619 #9]  INFO -- : [7c09f6c8-adf5-4eea-b5b3-6f8d216881c5] Started POST "/microposts" for 54.167.204.162 at 2018-02-10 08:36:46 +0000
2018-02-10T08:36:46.605647+00:00 app[web.1]: I, [2018-02-10T08:36:46.605579 #9]  INFO -- : [7c09f6c8-adf5-4eea-b5b3-6f8d216881c5] Processing by MicropostsController#create as HTML
2018-02-10T08:36:46.605722+00:00 app[web.1]: I, [2018-02-10T08:36:46.605666 #9]  INFO -- : [7c09f6c8-adf5-4eea-b5b3-6f8d216881c5]   Parameters: {"utf8"=>"✓", "authenticity_token"=>"AwAgHK6pMXVPbSV3hzo0j3g3vMcIIFZm9GnqNhCJrj/0Q7prGGu6DKnA596R+ho2Kr63fbV1lWk4ICsYsuknVQ==", "micropost"=>{"content"=>"of course i  still love you"}, "commit"=>"Post"}
2018-02-10T08:36:46.608473+00:00 app[web.1]: D, [2018-02-10T08:36:46.608388 #9] DEBUG -- : [7c09f6c8-adf5-4eea-b5b3-6f8d216881c5]   User Load (1.0ms)  SELECT  "users".* FROM "users" WHERE "users"."id" = $1 LIMIT $2  [["id", 102], ["LIMIT", 1]]
2018-02-10T08:36:46.611254+00:00 app[web.1]: D, [2018-02-10T08:36:46.611172 #9] DEBUG -- : [7c09f6c8-adf5-4eea-b5b3-6f8d216881c5]    (0.6ms)  BEGIN
2018-02-10T08:36:46.613707+00:00 app[web.1]: D, [2018-02-10T08:36:46.613615 #9] DEBUG -- : [7c09f6c8-adf5-4eea-b5b3-6f8d216881c5]   SQL (1.1ms)  INSERT INTO "microposts" ("content", "user_id", "created_at", "updated_at") VALUES ($1, $2, $3, $4) RETURNING "id"  [["content", "of course i  still love you"], ["user_id", 102], ["created_at", "2018-02-10 08:36:46.611756"], ["updated_at", "2018-02-10 08:36:46.611756"]]
2018-02-10T08:36:46.616573+00:00 app[web.1]: I, [2018-02-10T08:36:46.616506 #9]  INFO -- : [7c09f6c8-adf5-4eea-b5b3-6f8d216881c5] Redirected to https://sample-app-180103.herokuapp.com/
2018-02-10T08:36:46.615918+00:00 app[web.1]: D, [2018-02-10T08:36:46.615834 #9] DEBUG -- : [7c09f6c8-adf5-4eea-b5b3-6f8d216881c5]    (1.7ms)  COMMIT
2018-02-10T08:36:46.616762+00:00 app[web.1]: I, [2018-02-10T08:36:46.616707 #9]  INFO -- : [7c09f6c8-adf5-4eea-b5b3-6f8d216881c5] Completed 302 Found in 11ms (ActiveRecord: 4.4ms)
2018-02-10T08:36:46.921554+00:00 heroku[router]: at=info method=GET path="/" host=sample-app-180103.herokuapp.com request_id=0932fa0b-118d-42f6-9881-36f6b39aeaf7 fwd="54.167.204.162" dyno=web.1 connect=0ms service=20ms status=200 bytes=5069 protocol=https
2018-02-10T08:36:46.902498+00:00 app[web.1]: I, [2018-02-10T08:36:46.902382 #9]  INFO -- : [0932fa0b-118d-42f6-9881-36f6b39aeaf7] Started GET "/" for 54.167.204.162 at 2018-02-10 08:36:46 +0000
2018-02-10T08:36:46.903311+00:00 app[web.1]: I, [2018-02-10T08:36:46.903242 #9]  INFO -- : [0932fa0b-118d-42f6-9881-36f6b39aeaf7] Processing by StaticPagesController#home as HTML
2018-02-10T08:36:46.905639+00:00 app[web.1]: D, [2018-02-10T08:36:46.905564 #9] DEBUG -- : [0932fa0b-118d-42f6-9881-36f6b39aeaf7]   User Load (0.7ms)  SELECT  "users".* FROM "users" WHERE "users"."id" = $1 LIMIT $2  [["id", 102], ["LIMIT", 1]]
2018-02-10T08:36:46.908255+00:00 app[web.1]: I, [2018-02-10T08:36:46.908185 #9]  INFO -- : [0932fa0b-118d-42f6-9881-36f6b39aeaf7]   Rendering static_pages/home.html.erb within layouts/application
2018-02-10T08:36:46.910570+00:00 app[web.1]: D, [2018-02-10T08:36:46.910504 #9] DEBUG -- : [0932fa0b-118d-42f6-9881-36f6b39aeaf7]    (0.8ms)  SELECT COUNT(*) FROM "microposts" WHERE "microposts"."user_id" = $1  [["user_id", 102]]
2018-02-10T08:36:46.910737+00:00 app[web.1]: I, [2018-02-10T08:36:46.910681 #9]  INFO -- : [0932fa0b-118d-42f6-9881-36f6b39aeaf7]   Rendered shared/_user_info.html.erb (2.2ms)
2018-02-10T08:36:46.911178+00:00 app[web.1]: I, [2018-02-10T08:36:46.911112 #9]  INFO -- : [0932fa0b-118d-42f6-9881-36f6b39aeaf7]   Rendered shared/_error_messages.html.erb (0.0ms)
2018-02-10T08:36:46.911757+00:00 app[web.1]: I, [2018-02-10T08:36:46.911695 #9]  INFO -- : [0932fa0b-118d-42f6-9881-36f6b39aeaf7]   Rendered shared/_micropost_form.html.erb (0.9ms)
2018-02-10T08:36:46.912332+00:00 app[web.1]: D, [2018-02-10T08:36:46.912270 #9] DEBUG -- : [0932fa0b-118d-42f6-9881-36f6b39aeaf7]   CACHE  (0.0ms)  SELECT COUNT(*) FROM "microposts" WHERE "microposts"."user_id" = $1  [["user_id", 102]]
2018-02-10T08:36:46.913732+00:00 app[web.1]: D, [2018-02-10T08:36:46.913641 #9] DEBUG -- : [0932fa0b-118d-42f6-9881-36f6b39aeaf7]   Micropost Load (0.9ms)  SELECT  "microposts".* FROM "microposts" WHERE "microposts"."user_id" = $1 ORDER BY "microposts"."created_at" DESC LIMIT $2 OFFSET $3  [["user_id", 102], ["LIMIT", 30], ["OFFSET", 0]]
2018-02-10T08:36:46.915715+00:00 app[web.1]: I, [2018-02-10T08:36:46.915624 #9]  INFO -- : [0932fa0b-118d-42f6-9881-36f6b39aeaf7]   Rendered collection of microposts/_micropost.html.erb [1 times] (1.2ms)
2018-02-10T08:36:46.915960+00:00 app[web.1]: I, [2018-02-10T08:36:46.915870 #9]  INFO -- : [0932fa0b-118d-42f6-9881-36f6b39aeaf7]   Rendered shared/_feed.html.erb (4.0ms)
2018-02-10T08:36:46.916114+00:00 app[web.1]: I, [2018-02-10T08:36:46.916022 #9]  INFO -- : [0932fa0b-118d-42f6-9881-36f6b39aeaf7]   Rendered static_pages/_if_log_in_part.html.erb (7.6ms)
2018-02-10T08:36:46.916280+00:00 app[web.1]: I, [2018-02-10T08:36:46.916191 #9]  INFO -- : [0932fa0b-118d-42f6-9881-36f6b39aeaf7]   Rendered static_pages/home.html.erb within layouts/application (7.9ms)
2018-02-10T08:36:46.917358+00:00 app[web.1]: I, [2018-02-10T08:36:46.917259 #9]  INFO -- : [0932fa0b-118d-42f6-9881-36f6b39aeaf7]   Rendered layouts/_rails_default.html.erb (0.8ms)
2018-02-10T08:36:46.917660+00:00 app[web.1]: I, [2018-02-10T08:36:46.917563 #9]  INFO -- : [0932fa0b-118d-42f6-9881-36f6b39aeaf7]   Rendered layouts/_shim.html.erb (0.1ms)
2018-02-10T08:36:46.918666+00:00 app[web.1]: I, [2018-02-10T08:36:46.918574 #9]  INFO -- : [0932fa0b-118d-42f6-9881-36f6b39aeaf7]   Rendered layouts/_header.html.erb (0.8ms)
2018-02-10T08:36:46.919234+00:00 app[web.1]: I, [2018-02-10T08:36:46.919154 #9]  INFO -- : [0932fa0b-118d-42f6-9881-36f6b39aeaf7]   Rendered layouts/_footer.html.erb (0.2ms)
2018-02-10T08:36:46.919622+00:00 app[web.1]: I, [2018-02-10T08:36:46.919542 #9]  INFO -- : [0932fa0b-118d-42f6-9881-36f6b39aeaf7] Completed 200 OK in 16ms (Views: 9.8ms | ActiveRecord: 2.4ms)
2018-02-10T08:37:11.963508+00:00 app[web.1]: I, [2018-02-10T08:37:11.963419 #6]  INFO -- : [78b31c3c-e095-45c5-aa67-ea5fcc35f029] Started POST "/microposts" for 54.167.204.162 at 2018-02-10 08:37:11 +0000
2018-02-10T08:37:11.964318+00:00 app[web.1]: I, [2018-02-10T08:37:11.964241 #6]  INFO -- : [78b31c3c-e095-45c5-aa67-ea5fcc35f029] Processing by MicropostsController#create as HTML
2018-02-10T08:37:11.964441+00:00 app[web.1]: I, [2018-02-10T08:37:11.964385 #6]  INFO -- : [78b31c3c-e095-45c5-aa67-ea5fcc35f029]   Parameters: {"utf8"=>"✓", "authenticity_token"=>"9YyRLcM48eTWRRR34jv8wg86TDBDoczMYUpOWpR1XhICzwtadfp6nTDo1t70+9J7XbNHiv70D8OtA490NhXXeA==", "micropost"=>{"content"=>"of course i still love you ", "picture"=>#<ActionDispatch::Http::UploadedFile:0x000000059de310 @tempfile=#<Tempfile:/tmp/RackMultipart20180210-6-5raez6.png>, @original_filename="of_course_i_still_love_you.png", @content_type="image/png", @headers="Content-Disposition: form-data; name=\"micropost[picture]\"; filename=\"of_course_i_still_love_you.png\"\r\nContent-Type: image/png\r\n">}, "commit"=>"Post"}
2018-02-10T08:37:11.967134+00:00 app[web.1]: D, [2018-02-10T08:37:11.967035 #6] DEBUG -- : [78b31c3c-e095-45c5-aa67-ea5fcc35f029]   User Load (0.7ms)  SELECT  "users".* FROM "users" WHERE "users"."id" = $1 LIMIT $2  [["id", 102], ["LIMIT", 1]]
2018-02-10T08:37:12.108048+00:00 app[web.1]: D, [2018-02-10T08:37:12.107937 #6] DEBUG -- : [78b31c3c-e095-45c5-aa67-ea5fcc35f029]    (0.8ms)  BEGIN
2018-02-10T08:37:12.111060+00:00 app[web.1]: D, [2018-02-10T08:37:12.110966 #6] DEBUG -- : [78b31c3c-e095-45c5-aa67-ea5fcc35f029]   SQL (1.1ms)  INSERT INTO "microposts" ("content", "user_id", "created_at", "updated_at", "picture") VALUES ($1, $2, $3, $4, $5) RETURNING "id"  [["content", "of course i still love you "], ["user_id", 102], ["created_at", "2018-02-10 08:37:12.109064"], ["updated_at", "2018-02-10 08:37:12.109064"], ["picture", "of_course_i_still_love_you.png"]]
2018-02-10T08:37:15.043553+00:00 heroku[router]: at=info method=POST path="/microposts" host=sample-app-180103.herokuapp.com request_id=78b31c3c-e095-45c5-aa67-ea5fcc35f029 fwd="54.167.204.162" dyno=web.1 connect=1ms service=5913ms status=500 bytes=1891 protocol=https
2018-02-10T08:37:15.041675+00:00 app[web.1]: I, [2018-02-10T08:37:15.041608 #6]  INFO -- : [78b31c3c-e095-45c5-aa67-ea5fcc35f029] Completed 500 Internal Server Error in 3077ms (ActiveRecord: 3.5ms)
2018-02-10T08:37:15.041183+00:00 app[web.1]: D, [2018-02-10T08:37:15.041059 #6] DEBUG -- : [78b31c3c-e095-45c5-aa67-ea5fcc35f029]    (0.9ms)  ROLLBACK
2018-02-10T08:37:15.042449+00:00 app[web.1]: F, [2018-02-10T08:37:15.042386 #6] FATAL -- : [78b31c3c-e095-45c5-aa67-ea5fcc35f029]
2018-02-10T08:37:15.042575+00:00 app[web.1]:   :body          => "<?xml version=\"1.0\" encoding=\"UTF-8\"?>\n<Error><Code>AuthorizationHeaderMalformed</Code><Message>The authorization header is malformed; the region 'us-east-1' is wrong; expecting 'us-west-2'</Message><Region>us-west-2</Region><RequestId>887F68335D42F1AF</RequestId><HostId>SyC39MW8piA8UwmHaUalcPWlOodGiA+dRHM4P8G9uMqmruTQDyhbzuZ/1gUkllhmVk1jX3+Iafc=</HostId></Error>"
2018-02-10T08:37:15.042555+00:00 app[web.1]: excon.error.response
2018-02-10T08:37:15.042553+00:00 app[web.1]: F, [2018-02-10T08:37:15.042492 #6] FATAL -- : [78b31c3c-e095-45c5-aa67-ea5fcc35f029] Excon::Error::BadRequest (Expected(200) <=> Actual(400 Bad Request)
2018-02-10T08:37:15.042580+00:00 app[web.1]:   :headers       => {
2018-02-10T08:37:15.042577+00:00 app[web.1]:   :cookies       => [
2018-02-10T08:37:15.042579+00:00 app[web.1]:   ]
2018-02-10T08:37:15.042581+00:00 app[web.1]:     "Connection"       => "close"
2018-02-10T08:37:15.042585+00:00 app[web.1]:     "Server"           => "AmazonS3"
2018-02-10T08:37:15.042584+00:00 app[web.1]:     "Date"             => "Sat, 10 Feb 2018 08:37:14 GMT"
2018-02-10T08:37:15.042587+00:00 app[web.1]:     "x-amz-id-2"       => "SyC39MW8piA8UwmHaUalcPWlOodGiA+dRHM4P8G9uMqmruTQDyhbzuZ/1gUkllhmVk1jX3+Iafc="
2018-02-10T08:37:15.042589+00:00 app[web.1]:   }
2018-02-10T08:37:15.042591+00:00 app[web.1]:   :host          => "users-picture.s3.amazonaws.com"
2018-02-10T08:37:15.042592+00:00 app[web.1]:   :local_address => "172.17.86.206"
2018-02-10T08:37:15.042583+00:00 app[web.1]:     "Content-Type"     => "application/xml"
2018-02-10T08:37:15.042588+00:00 app[web.1]:     "x-amz-request-id" => "887F68335D42F1AF"
2018-02-10T08:37:15.042595+00:00 app[web.1]:   :path          => "/uploads/micropost/picture/19/of_course_i_still_love_you.png"
2018-02-10T08:37:15.042597+00:00 app[web.1]:   :reason_phrase => "Bad Request"
2018-02-10T08:37:15.042593+00:00 app[web.1]:   :local_port    => 38558
2018-02-10T08:37:15.042599+00:00 app[web.1]:   :status        => 400
2018-02-10T08:37:15.042596+00:00 app[web.1]:   :port          => 443
2018-02-10T08:37:15.042605+00:00 app[web.1]: F, [2018-02-10T08:37:15.042546 #6] FATAL -- : [78b31c3c-e095-45c5-aa67-ea5fcc35f029]
2018-02-10T08:37:15.042600+00:00 app[web.1]:   :status_line   => "HTTP/1.1 400 Bad Request\r\n"
2018-02-10T08:37:15.042628+00:00 app[web.1]: F, [2018-02-10T08:37:15.042588 #6] FATAL -- : [78b31c3c-e095-45c5-aa67-ea5fcc35f029] app/controllers/microposts_controller.rb:11:in `create'
2018-02-10T08:37:15.042598+00:00 app[web.1]:   :remote_ip     => "52.218.208.146"
2018-02-10T08:37:15.042601+00:00 app[web.1]: ):

报错出现的条件：

仅在创建一个含有图片的微博的时候报错，若只是创建一个纯文字微博就不会报错

如何流程图表示下面的算法?

Mind — Sun, 19 Nov 2017 11:14:56 +0800

def fibonacci(number)
    if number < 2
        number 
    else
      fibonacci(number - 1) + fibonacci(number - 2)
    end
end

Ruby 的面向对象编程

Mind — Fri, 10 Nov 2017 21:49:50 +0800

1.面向对象编程：

1.0 为何要有面向对象编程：

很早之前程序员就发现，随着软件的日趋复杂与庞大，维护往往变成了一个很棘手的问题。因为贯穿整个程序的依赖 (dependencies),在一个程序中一个很小的改变就可能引起如同涟漪般扩散的偏差 (errors).

而面向对象编程正是为了解决这个问题而诞生的。

1.1 何为面向对象编程：

面向对象编程 (Object oriented programming) 是一种基于对象的编程范型。在面向对象编程语言中，一切均是对象。

1.2 对象 (object) 的定义：

对象是指一个具体的事物。它有具体的行为 (behaviors),有具体的属性 (states).有时可以对应现实世界的事物，例如小狗聪聪，猫咪毛毛等。

1.3 类 (class) 的定义：

定义：

类相当于一副蓝图，定义了一类事物的抽象特点。例如，"狗"这个类会包含狗的一切基础特征，即所有“狗”都共有的特征或行为，例如它的孕育、毛皮颜色和吠叫的能力。

作用：

这样创建一类具有相同行为与共通的属性的对象时，先创建一个这样的一个类，再用这个类去定义具体的对象，就可以少写很多代码。

1.4 面向对象编程的三大支柱：

封装性 (Encapsulation)

限定只有特定的类的对象才能调用特定类的方法，并且隐藏了方法的具体执行步骤。

示例：

/* 一个面向过程的程序会这样写： */
定义莱丝
莱丝.设置音调(5)
莱丝.吸气()
莱丝.吐气()

/* 而当狗的吠叫被封装到类中，任何人都可以简单地使用： */
定义莱丝是狗
莱丝.吠叫()

继承 (inheritance)

在某些情况下一个类会有子类，子类比父类更加具体。例如，“狗”这个类可能会有它的子类"牧羊犬"和"吉娃娃".子类会继承父类的属性和行为，并且包含它自己的。假设"狗"这个类有一个方法 (行为) 叫做“吠叫 ()”和一个属性叫做“毛皮颜色”。它的子类（前例中的牧羊犬和吉娃娃犬）会继承这些成员。

例如：

类牧羊犬:继承狗

定义莱丝是牧羊犬
莱丝.吠叫()    /* 注意这里调用的是狗这个类的吠叫方法。*/

多态 (Polymorphism)

多态 (Polymorphism) 是一个专业术语，意指"许多形态"("many shapes").更具体来说是同一种操作被用不同方式执行。

例如，狗和鸡都有“叫 ()”这一方法，但是调用狗的“叫 ()”，狗会吠叫；调用鸡的“叫 ()”，鸡则会啼叫。我们将它体现在伪代码上：

类狗
开始
   公有成员:
       叫()
       开始
          吠叫()
       结束
结束

类鸡
开始
   公有成员:
       叫()
       开始
          啼叫()
       结束
结束

定义莱丝是狗
定义鲁斯特是鸡
莱丝.叫()
鲁斯特.叫()

这样同样做出叫这个动作，莱丝与鲁斯特的实际行为会大相径庭。

2. 关于对象 (object)

2.1 initialize object:

语法：

Classname.new

示例：

不带参数：

--- initialize class called GoodDog ---
class GoodDog 

end 

--- initialize object ----
sparky=GoodDog.new

带参数：

--- initialize class called GoodDog ---
class GoodDog 
    def initialize(name,color)
        @name = name
        @color = color
    end 
end 

--- initialize object ----

sparky=GoodDog.new("sparky","white")

2.2 instance variable

2.2.1 作用：

记录对象的属性 (keep track of states of object)

2.2.2 定义语法：

以"@"符号开头

后面跟着表示对象属性的单词，并且使用小写字母

示例：

class GoodDog 
    def initialize(name,color)
        @name = name
        @color = color
    end 
end 

sparky = GoodDog.new("sparky","white")

2.2.3 instance variable 的存取：

2.2.3.1 如何进行存取：

背景问题 1:

如何输出@name的值

以上面代码为例，虽然有了 instance variable，但是如果我们想要输出 sparky 的 name，那么应该怎么办？

sparky.name # => NoMethodError: undefined method `name' for #<GoodDog:0x007f91821239d0
  @name="Sparky">

上面的错误提示告诉我们我们没有定义一个叫做 name 的 method，也就是说我们需要定义一个方法来存放@name的值，来方便我们输出。

~~这似乎是说"object."后面只能跟 method，而不能跟 variable~~

解决方案：

class GoodDog 
    def initialize(name,color)
        @name = name
        @color = color
    end 

--- add getter_method ---   

    def get_name
        @name
    end
end 

sparky = GoodDog.new("sparky","white")

这样我们就可以输出 sparky 的名字了：

puts sparky.get_name # => sparky

背景问题 2:

现在已经有了 getter method,

但如何改变 name 的值？

解决方案：

class GoodDog 
    def initialize(name,color)
        @name = name
        @color = color
    end 

--- add getter_method ---   

    def get_name
        @name
    end

--- add setter_method ---

    def set_name=(name)
        @name = name 
    end
end 

sparky = GoodDog.new("sparky","white")

现在运行下面的代码：

sparky.set_name = "spartacus"
puts sparky.get_name    #=> spartacus

就会发现 name 的值改变了。

2.2.3.2 对上述代码进行重构：

重构的原因：

Rubyist 习惯使用相同的名称来命名 instance variable 的 getter method 和 setter method .

重构后的代码：

统一使用 name 来命名 getter method 和 setter method.

class GoodDog
  def initialize(name)
    @name = name
  end

  def name                      # This was renamed from "get_name"
    @name
  end

  def name=(n)                  # This was renamed from "set_name="
    @name = n
  end
end

sparky = GoodDog.new("Sparky")
puts sparky.speak
puts sparky.name            # => "sparky"
sparky.name = "Spartacus"
puts sparky.name            # => "Spartacus"

2.2.3.3 对上述代码进行再次重构 (attr_*):

重构的原因：

上述代码占用的空间太多了，只有一个 instance variable 还好，若是有多个呢？例如 height / weight.这样就太麻烦了。

解决方案：

Ruby 内置了一套方案来解决上述问题。

attr_accessor method 可以自动的帮助我们产生和上面一样的 getter / setter metods.

class GoodDog
    attr_accessor :name         # using attr_accessor method 

    def initialize(name)
      @name = name
    end

end

  sparky = GoodDog.new("Sparky")
  puts sparky.speak
  puts sparky.name            # => "Sparky"
  sparky.name = "Spartacus"
  puts sparky.name            # => "Spartacus"

这样写就会简洁/方便很多。

含有多个 instance variable 的写法：

attr_accessor :name, :height, :weight

2.2.3.4 其他两种 attr_* method:

只想要 getter method，而不需要 setter method :

attr_reader

只想要 setter method ,而不想要 getter method:

attr_writer

2.2.4 在 class 内部使用 getter / setter method:

2.2.4.1 在 class 内部使用 getter method 替换 instance variable:

原因：

如果我们有一个 social_security_numbers(用@ssn表示),我们并不想展示所有的数字，只想展示后四位，那么可以这样写：

"****-****-" + @ssn.split("-").last

如果我们需要多次使用到这行代码，与其多次重复写入，不如写一个 method 将这行代码封装起来。

另外原本的 getter mehod 不能让别人直接调用，所以不如直接使用 getter method 来封装这行代码：

def ssn
    "****-****-" + @ssn.split("-").last    
end

示例：

class Account

  def initialize(name,ssn)
      @name = name
      @ssn =ssn
  end 

  def ssn
      "****-****-" + @ssn.split("-").last    
    end   

  def ssn_hint
      "Your ssn is #{ssn}"        #  using ssn instead of @ssn
  end

end

2.2.4.2 在 class 内部使用 setter method:

原因：

如实在 GoodDog class 中有多个 instance variable，而我们定义一个方法 (change_info) 用来同时改变着多变量的值：

def change_info(n,h,w)
    @name = n
    @height = h 
    @weight = w
end

为了与上面的在 class 内部使用 getter method 保持一致 (consistence),从而使用 setter_method 来进行替换。

失败的尝试：

根据上面的思路我们对 change_info 这个 method 进行了修改。

class GoodDog
    attr_accessor :name, :height, :weight

    def initialize(n, h, w)
      @name = n
      @height = h
      @weight = w
    end

    def speak
      "#{name} says arf!"
    end

    def change_info(n, h, w)        # try using setter method
      name = n
      height = h
      weight = w
    end

    def info
      "#{name} weighs #{weight} and is #{height} tall."
     end

但是当我们进行检测时，却发现变量的值并没有改变。

sparky = GoodDog.new('Sparky', '12 inches', '10 lbs')

puts sparky.info      # => Sparky weighs 10 lbs and is 12 inches tall.

sparky.change_info('Spartacus', '24 inches', '45 lbs')

puts sparky.info      # => Spartacus weighs 45 lbs and is 24 inches tall.

失败的原因：

在上述代码中 Ruby 误以为我们是想创建新的变量，分别叫 name/height/weight 了。

所以就会发现@name等变量并没有改变。

使用 self method 进行修正：

def change_info(n, h, w)        # using self method
  self.name = n
  self.height = h
  self.weight = w
end

为了保持一致，统一将调用 getter method 的地方加上 self.

def info
    "#{self.name} weighs #{self.weight} and is #{self.height} tall."
end

最终结果是形成一个惯例 (convention):

class 内，用到 instance variable 的地方使用 getter method ;

class 内，除 setter method 以外，需要改变 instance variable 值的地方统一使用 setter method;

在 class 内使用到 getter / setter method 的地方都使用 self method

3.关于类 (class)

3.1 class variable:

3.1.1 作用：

不知道怎么描述，所以通过下面的代码进行感受。

3.1.2 定义方法：

语法：

使用"@@"作为开头;

紧跟着是能够描述想要记录属性的小写的英文单词。

示例：

class GoodDog
  @@number_of_dogs = 0

  def initialize
    @@number_of_dogs += 1
  end

end

3.2 类方法 (class method):

3.2.1 作用：

3.2.2 定义方法：

语法：

使用 self method;

用小写单词命名。

示例：

class GoodDog
  @@number_of_dogs = 0

  def initialize
    @@number_of_dogs += 1
  end

  def self.total_number_of_dogs
    @@number_of_dogs
  end 
end

puts GoodDog.total_number_of_dogs   # => 0
dog1 = GoodDog.new
dog2 = GoodDog.new
puts GoodDog.total_number_of_dogs   # => 2

3.3 常量 (constants):

其实和 class 并没有什么关系。

3.3.1 为什么要有常量：

有时候我们无论如何都不想要定义的量的值改变，这时就使用常量。

3.3.2 常量的定义方法：

语法：

使用首字母大写的英语单词;

Rubyist 习惯上将常量的所有字母都大写。

示例：

class GoodDog
    DOG_YEARS = 7                   # constants

    attr_accessor :name, :age

    def initialize(n, a)
      self.name = n
      self.age  = a * DOG_YEARS
    end 
end

sparky = GoodDog.new("Sparky", 4)
puts sparky.age

3.4 The to_s method:

这部分其实和 class 也没有什么关系。

3.4.1 自动调用 to_s method 的两种情况 :

puts method 自动调用 to_method.

示例：

---这里输出的结果是:前面是sparky这个对象对应的class(GoodDog),紧跟的一串数字/字母是这个是这个对象的ID编码---

puts sparky      # => #<GoodDog:0x007fe542323320>

puts sparky 等价于 puts sparky.to_s

字符串插值 (string interpolation) 自动调用 to_s method:
- 字符串插值 (string interpolation) 就是将常量或者变量插入字符串中。

示例：

irb :001 > arr = [1, 2, 3]
  => [1, 2, 3]
  irb :002 > x = 5
  => 5
  irb :003 > "The #{arr} array doesn't include #{x}."
  => The [1, 2, 3] array doesn't include 5.

在这里字符串插值自动的调用 to_s method，然后将 arr 和 x 两个变量转换成了对应的值，然后与字符串结合在了一起。

3.4.2 了解 to_s method 的自动调用的益处：

虽然当前感觉了解 to_s method 是无关紧要的，但这却会在日后帮助我们更好的读写 oo code.

3.5 进一步了解 self method

上面有两处使用了 self method:

告诉 Ruby 我们想要调用的是 setter method，而不是创建新的变量;

使用 self method 帮助定义 class method.

那么 self 究竟是什么？

3.5.1 self 指代 object:

代码示例

class GoodDog
    # ... rest of code omitted for brevity
    def what_is_self
      self
end end

sparky = GoodDog.new('Sparky', '12 inches', '10 lbs')
  p sparky.what_is_self
   # => #<GoodDog:0x007f83ac062b38 @name="Sparky", @height="12 inches",
  @weight="10 lbs">

通过上述代码我们可以发现 self 指代的是 object(sparky)

3.5.2 self 指代 class:

代码示例：

class GoodDog
    # ... rest of code omitted for brevity
    puts self
end

irb :001 > GoodDog
  => GoodDog

通过上面我们得出 self 指代的是 GoodDog 这个 class.

3.5.3 如何判断 self 指代什么：

self,insideofaninstancemethod,referencestheinstance(object)thatcalledthemethod - the calling object. Therefore, self.weight= is the same as sparky.weight= ,in our example.

self,outsideofaninstancemethod,referencestheclassandcanbeusedtodefineclass methods. Therefore, def self.name=(n) is the same as def GoodDog.name=(n) ,in our example.

4. 继承 (inheritance)

4.0 继承的对象：

继承的东西是 superclass 中的 behavior.

4.1 继承的作用：

通过继承能够实现代码复用，从而达到以下好处：

除去写重复代码的麻烦;
方便 debug.

4.1 继承的两种方式：

class inheritance
mixing in module

4.2 class inheritance:

4.2.1 语法：

使用 <符号去标记继承方向。

示例：

class Animal
  def speak
    "Hello!" 
  end
end

class GoodDog < Animal          # 标记GoodDog从Animal继承behavior
end

class Cat < Animal
end

sparky = GoodDog.new
paws = Cat.new
puts sparky.speak           # => Hello!
puts paws.speak             # => Hello!

4.2.2 继承 behavior 的 overring

当 subclass 中有与 superclass 中想相同的 method 时，subclass 的 object 调用的就是 subclass 中的 method.

示例：

class Animal
    def speak
        "Hello!"
    end
end

class GoodDog < Animal

    attr_accessor :name

    def initialize(n)
      self.name = n
    end

    def speak
      "#{self.name} says arf!"
    end 
end

class Cat < Animal
end

sparky = GoodDog.new("Sparky")
paws = Cat.new
puts sparky.speak           # => Sparky says arf!
puts paws.speak             # => Hello!

4.3 super

4.3.1 作用

在 subclass 中调用 superclass 中与 instance method 同名 method.

示例：

class Animal
    def speak
        "Hello!" 
    end
end

class GoodDog < Animal
    def speak
      super + " from GoodDog class"
    end
end

sparky = GoodDog.new
sparky.speak             # => "Hello! from GoodDog class"

4.3.2 调用 super 的三种状况：

不含参数：

class Animal
    def speak
        "Hello!" 
    end
end

class GoodDog < Animal
    def speak
      super + " from GoodDog class"
    end
end

sparky = GoodDog.new
sparky.speak             # => "Hello! from GoodDog class"

含参数，但是不指定：

class Animal
    attr_accessor :name

    def initialize(name)
       @name = name
    end 
end

class GoodDog < Animal
    def initialize(color)
      super
      @color = color
    end
end

---这里因为使用了super 所以初始化object的时候调用了Animal中的initialze method,从而导致bruno多了一个属性--name ---

bruno = GoodDog.new("brown")        # => #<GoodDog:0x007fb40b1e6718,@color="brown", @name="brown">

指定参数：

class BadDog < Animal
    def initialize(age, name)
        super(name)
        @age = age 
    end
end

BadDog.new(2, "bear")           # => #<BadDog:0x007fb40b2beb68 @age=2,@name="bear">

4.4 Mixing in module

4.4.1 为什么要有 mixing in module:

[图片上传失败...(image-614c12-1510277893483)]

已上图为例，如实 Cat 与 Dog 有相同的 behavior，这个时候我们就可以将它提取出来，放在 Mammal 中，通过继承来使用。

那么问题来了，Dog 与 Fish 也有相同的 behavior—swim，这个时候显然不能将对应的 method 提取出来放到 Mammal 或者是 Animal 中 (因为 Cat 不可以 swim).解决方案就是使用 Mixing in module .

4.4.2 mixing in module 的思路

就是将两个或者多个无法通过继承来 dry up 的 code 封装到一个容器中，然后让这些 class 调用这个容器中的内容。

具体来说是这样。将 Fish 与 Dog 都有的 behavior(swim) 用 Swimmable 这个 module 进行封装，然后让 Fish 与 Dog 进行调用。

4.4.3 mixing in module 的定义：

示例：

module Swimmable
    def swim
        "I'm swim."
    end 
end

解释：

使用首字母大写的单词;

rubyist 习惯上将单词以 able 作为后缀。

4.4.4 mixing in module 的使用：

module Swimmable
  def swim
    "I'm swimming!"
  end
end

class Animal; end

class Fish < Animal
  include Swimmable     # mixing in Swimmable module
end

class Mammal < Animal
end

class Cat < Mammal
end

class Dog < Mammal
  include Swimmable     # mixing in Swimmable module
end

语法：

include modulename

5.其他：

5.1 Method lookup path:

5.1.1 定义：

object 在调用方法 (method) 时，是按照一定顺序进行的，这个顺序就叫 method loopup path.

5.1.2 知道 method lookup path 的作用：

当我们研究一个较大的项目时，可能会困惑于那些方法是哪来的。但是若是知道了 method lookup path，便能够较好的理解那些方法是在哪儿，以及是如何组织的。

5.1.3 使用 ancestors 查询 method lookup path:

以下述代码为例，如何才能知道 Animal 的 object 的 method loopup path 呢？

module Walkable
    def walk
      "I'm walking."
    end
end

module Swimmable
    def swim
      "I'm swimming."
    end
end

module Climbable
    def climb
      "I'm climbing."
    end
end

class Animal
    include Walkable

    def speak
      "I'm an animal, and I speak!"
    end 
end

使用 ancestors method :

puts "---Animal method lookup---"
  puts Animal.ancestors

结果：

--- Animal method lookup ---
Animal
Walkable
Object
Kernel
BasicObject

5.1.4 method lookup path:

顺序：

在初始化对象的类中查找

在该对象的 module 中查找 (按照 mixing 进的 module 的顺序，进行倒序查找)

在该类的父类中查找

示例：

module Walkable
    def walk
      "I'm walking."
    end
end

module Swimmable
    def swim
      "I'm swimming."
    end
end

module Climbable
    def climb
      "I'm climbing."
    end
end

class Animal
    include Walkable

    def speak
      "I'm an animal, and I speak!"
    end 
end

class GoodDog < Animal
    include Swimmable
    include Climbable
end

puts "---GoodDog method lookup---"
puts GoodDog.ancestors

输出结果：

---GoodDog method lookup path ---
GoodDog
Climbable
Swimmable
Animal
Walkable
Object
Kernel
BasicObject

5.2 module 的另外两种用法：

1.用于 namespacing;

2.作为 container of methods

5.2.1 用于 namespacing:

作用：

将同类型的 class 归类放在一起;
区分具有相同名字的 class

定义方法：

module Mammal
    class Dog
      def speak(sound)
        p "#{sound}"
      end 
    end

    class Cat
      def say_name(name)
        p "#{name}"
      end
    end 
end

如何使用 module 中的 class 初始化对象：

buddy = Mammal::Dog.new
kitty = Mammal::Cat.new
buddy.speak('Arf!')           # => "Arf!"
kitty.say_name('kitty')       # => "kitty"

5.2.2 作为 container of methods (module methods)

定义方法：

module Mammal
    ...
    def self.some_out_of_place_method(num)
      num ** 2
    end 
end

调用方法：

法一：

value = Mammal.some_out_of_place_method(4)

法二：

value = Mammal::some_out_of_place_method(4)

5.3 私有/公共/保护方法 (private/public/protected):

5.3.1 私有方法 (private method)

作用：

有时候我们只想让某个方法在 class 内部发生作用，而不再外部被调用，这个时候就使用 private method.

定义方法：

使用保留字:private

class GoodDog
  DOG_YEARS = 7

   attr_accessor :name, :age

   def initialize(n, a)
      self.name = n
      self.age = a
    end

    private             # method following "private is pirvate method

    def human_years
      age * DOG_YEARS
    end 
end

sparky = GoodDog.new("Sparky", 4)
sparky.human_years

说明：

私有方法 (private method) 只能在 instance method 中被调用，且是直接调用不能用 self method.

即使是 objectname.privatemethod 的形式也不行。

5.3.2 保护方法 (protected method)

作用：

有时候我们想要在 instance method 中使用 self.privatemethod 或者 objectname.privatemethod，的形式，但是有不想外界调用，这是就使用 protected method.

语法：

使用保留字:protected

class Animal

    def a_public_method
      "Will this work? " + self.a_protected_method
    end

    protected

    def a_protected_method
      "Yes, I'm protected!"
    end 
end

class Student
      def initialize(name, grade)
        @name = name
        @grade = grade
      end

      def better_grade_than?(other_student)
        grade > other_student.grade
      end

      protected

      def grade
        @grade
      end 
end

joe = Student.new("Joe", 90)
bob = Student.new("Bob", 84)
puts "Well done!" if joe.better_grade_than?(bob)

5.4 偶发的方法重写 (accidental method overrding)

5.4.1 产生原因：

因为所有自己创建的类都继承自 class Object，这就导致当有些 method 与 Object 中的 method 同名时，发生 method overring.

示例：

例如:Object 的 send method 可以调用某个方法，但是若被重写了，就会出问题。

class Child
    def say_hi
      p "Hi from Child."
    end

    def send
      p "send from Child..."
    end 
end

lad = Child.new
lad.send :say_hi

报错：

ArgumentError: wrong number of arguments (1 for 0)
from (pry):12:in `send'

5.4.2 启示：

要熟知一些常见的 Object methods，避免发生重写 (overrding),否则会对应用造成灾难性的后果。