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張 旭

File: README - Documentation by YARD 0.8.7.6 - 0 views

rspec.info/...rspec-core

rails ruby test programming rspec

shared by 張 旭 on 14 Jun 17 - No Cached
  • we can express concepts like a conversation
    • 張 旭
      張 旭 on 14 Jun 17
       
      描述 order 這個東西。 order 就是將登記在它上面的物品價格加總起來。
  • The describe method creates an ExampleGroup.
  • ...15 more annotations...
  • declare examples using the it method
  • an example group is a class in which the block passed to describe is evaluated
  • The blocks passed to it are evaluated in the context of an instance of that class
  • nested groups using the describe or context methods
  • can declare example groups using either describe or context
  • can declare examples within a group using any of it, specify, or example
  • Declare a shared example group using shared_examples, and then include it in any group using include_examples.
  • Nearly anything that can be declared within an example group can be declared within a shared example group.
  • shared_context and include_context.
  • When a class is passed to describe, you can access it from an example using the described_class method
  • rspec-core stores a metadata hash with every example and group
  • Example groups are defined by a describe or context block, which is eagerly evaluated when the spec file is loaded
  • Examples -- typically defined by an it block -- and any other blocks with per-example semantics -- such as a before(:example) hook -- are evaluated in the context of an instance of the example group class to which the example belongs.
  • Examples are not executed when the spec file is loaded
  • run any examples until all spec files have been loaded
張 旭

A Good Vimrc - 1 views

dougblack.io/...a-good-vimrc.html

vim programming development

shared by 張 旭 on 15 Apr 17 - No Cached
  • Don't put any lines in your vimrc that you don't understand.
  • the absolute worst way to make your environment better is to just copy it wholesale from others
  • adding features one by one to your vimrc aids in overall Vim comprehension
  • ...3 more annotations...
  • custom keybindings
  • Vim doesn't model undo as a simple stack. In Vim it's a tree.
  • Don't put anything in your .vimrc you don't understand!
張 旭

The Exhaustive Guide to Rails Time Zones - Alexander Danilenko - 0 views

danilenko.org/...rails_timezones

rails programming ruby time

shared by 張 旭 on 16 Apr 17 - No Cached
  • you can use "wrong" methods in development and fairly often get valid results. But then you'll face with unexpected problems on production.
  • Ruby provides two classes to manage time: Time and DateTime
  • that's in Ruby! When it comes to Rails things get a bit more complicated
  • ...15 more annotations...
  • Rails gives your ability to configure application time zone.
  • we have 3 (!) different time zones in our application: system time, application time and database time.
  • DateTime.now and Time.now both give you the time in system time zone
  • Ruby standard library methods that know nothing about Rails time zone configuration
  • It's not Rails responsible for adding time zone, but ActiveSupport
  • switch from Time.now to Time.zone.now
  • Time.zone.now
  • no need to use it explicitly as there is shorter and more clear option.
  • Time.zone.today
  • Time.zone.local
  • Time.zone.at
  • Time.zone.parse
  • DateTime.strptime(str, "%Y-%m-%d %H:%M %Z").in_time_zone
  • always keep in mind that when you build time or date object you should respect current time zone.
  • use Time.zone instead of Time, Date or DateTime
張 旭

Introducing Infrastructure as Code | Linode - 0 views

www.linode.com/...tion-to-infrastructure-as-code

devops server infrastructure

shared by 張 旭 on 14 Apr 21 - No Cached
  • Infrastructure as Code (IaC) is a technique for deploying and managing infrastructure using software, configuration files, and automated tools.
  • With the older methods, technicians must configure a device manually, perhaps with the aid of an interactive tool. Information is added to configuration files by hand or through the use of ad-hoc scripts. Configuration wizards and similar utilities are helpful, but they still require hands-on management. A small group of experts owns the expertise, the process is typically poorly defined, and errors are common.
  • The development of the continuous integration and continuous delivery (CI/CD) pipeline made the idea of treating infrastructure as software much more attractive.
  • ...20 more annotations...
  • Infrastructure as Code takes advantage of the software development process, making use of quality assurance and test automation techniques.
  • Consistency/Standardization
  • Each node in the network becomes what is known as a snowflake, with its own unique settings. This leads to a system state that cannot easily be reproduced and is difficult to debug.
  • With standard configuration files and software-based configuration, there is greater consistency between all equipment of the same type. A key IaC concept is idempotence.
  • Idempotence makes it easy to troubleshoot, test, stabilize, and upgrade all the equipment.
  • Infrastructure as Code is central to the culture of DevOps, which is a mix of development and operations
  • edits are always made to the source configuration files, never on the target.
  • A declarative approach describes the final state of a device, but does not mandate how it should get there. The specific IaC tool makes all the procedural decisions. The end state is typically defined through a configuration file, a JSON specification, or a similar encoding.
  • An imperative approach defines specific functions or procedures that must be used to configure the device. It focuses on what must happen, but does not necessarily describe the final state. Imperative techniques typically use scripts for the implementation.
  • With a push configuration, the central server pushes the configuration to the destination device.
  • If a device is mutable, its configuration can be changed while it is active
  • Immutable devices cannot be changed. They must be decommissioned or rebooted and then completely rebuilt.
  • an immutable approach ensures consistency and avoids drift. However, it usually takes more time to remove or rebuild a configuration than it does to change it.
  • System administrators should consider security issues as part of the development process.
  • Ansible is a very popular open source IaC application from Red Hat
  • Ansible is often used in conjunction with Kubernetes and Docker.
  • Linode offers a collection of several Ansible guides for a more comprehensive overview.
  • Pulumi permits the use of a variety of programming languages to deploy and manage infrastructure within a cloud environment.
  • Terraform allows users to provision data center infrastructure using either JSON or Terraform’s own declarative language.
  • Terraform manages resources through the use of providers, which are similar to APIs.
張 旭

What exactly was the point of [ "x$var" = "xval" ]? - Vidar's Blog - 0 views

www.vidarholen.net/...blog

shell programming code

shared by 張 旭 on 21 Apr 21 - No Cached
  • x-hack
  • test "x$arg" = "x-f"
  • the utility used a simple recursive descent parser without backtracking, which gave unary operators precedence over binary operators and ignored trailing arguments.
  • ...3 more annotations...
  • The x-hack is effective because no unary operators can start with x.
  • the x-hack could be used to work around certain bugs all the way up until 2015, seven years after StackOverflow wrote it off as an archaic relic of the past!
  • The Dash issue of [ "(" = ")" ] was originally reported in a form that affected both Bash 3.2.48 and Dash 0.5.4 in 2008. You can still see this on macOS bash today
  • 張 旭 on 21 Apr 21
     
    "x$var"
張 旭

Custom Resources | Kubernetes - 0 views

kubernetes.io/...custom-resources

kubernetes

shared by 張 旭 on 11 May 21 - No Cached
  • Custom resources are extensions of the Kubernetes API
  • A resource is an endpoint in the Kubernetes API that stores a collection of API objects of a certain kind
  • Custom resources can appear and disappear in a running cluster through dynamic registration
  • ...30 more annotations...
  • Once a custom resource is installed, users can create and access its objects using kubectl
  • When you combine a custom resource with a custom controller, custom resources provide a true declarative API.
  • A declarative API allows you to declare or specify the desired state of your resource and tries to keep the current state of Kubernetes objects in sync with the desired state.
  • Custom controllers can work with any kind of resource, but they are especially effective when combined with custom resources.
  • The Operator pattern combines custom resources and custom controllers.
  • the API represents a desired state, not an exact state.
  • define configuration of applications or infrastructure.
  • The main operations on the objects are CRUD-y (creating, reading, updating and deleting).
  • The client says "do this", and then gets an operation ID back, and has to check a separate Operation object to determine completion of the request.
  • The natural operations on the objects are not CRUD-y.
  • High bandwidth access (10s of requests per second sustained) needed.
  • Use a ConfigMap if any of the following apply
  • You want to put the entire config file into one key of a configMap.
  • You want to perform rolling updates via Deployment, etc., when the file is updated.
  • Use a secret for sensitive data, which is similar to a configMap but more secure.
  • You want to build new automation that watches for updates on the new object, and then CRUD other objects, or vice versa.
  • You want the object to be an abstraction over a collection of controlled resources, or a summarization of other resources.
  • CRDs are simple and can be created without any programming.
  • Aggregated APIs are subordinate API servers that sit behind the primary API server
  • CRDs allow users to create new types of resources without adding another API server
  • Defining a CRD object creates a new custom resource with a name and schema that you specify.
  • The name of a CRD object must be a valid DNS subdomain name
  • each resource in the Kubernetes API requires code that handles REST requests and manages persistent storage of objects.
  • The main API server delegates requests to you for the custom resources that you handle, making them available to all of its clients.
  • The new endpoints support CRUD basic operations via HTTP and kubectl
  • Custom resources consume storage space in the same way that ConfigMaps do.
  • Aggregated API servers may use the same storage as the main API server
  • CRDs always use the same authentication, authorization, and audit logging as the built-in resources of your API server.
  • most RBAC roles will not grant access to the new resources (except the cluster-admin role or any role created with wildcard rules).
  • CRDs and Aggregated APIs often come bundled with new role definitions for the types they add.
張 旭

CS50 - 0 views

cs50.harvard.edu/...fall

programming code

shared by 張 旭 on 21 Jun 21 - No Cached
張 旭

mvn clean install - a short guide to Maven - 0 views

www.marcobehler.com/...install-a-short-guide-to-maven

programming java

shared by 張 旭 on 12 Aug 20 - No Cached
  • An equivalent in other languages would be Javascript’s npm, Ruby’s gems or PHP’s composer.
  • Maven expects a certain directory structure for your Java source code to live in and when you later do a mvn clean install , the whole compilation and packaging work will be done for you.
  • any directory that contains a pom.xml file is also a valid Maven project.
  • ...17 more annotations...
  • A pom.xml file contains everything needed to describe your Java project.
  • Java source code is to be meant to live in the "/src/main/java" folder
  • Maven will put compiled Java classes into the "target/classes" folder
  • Maven will also build a .jar or .war file, depending on your project, that lives in the "target" folder.
  • Maven has the concept of a build lifecycle, which is made up of different phases.
  • clean is not part of Maven’s default lifecycle, you end up with commands like mvn clean install or mvn clean package. Install or package will trigger all preceding phases, but you need to specify clean in addition.
  • Maven will always download your project dependencies into your local maven repository first and then reference them for your build.
  • local repositories (in your user’s home directory: ~/.m2/)
  • clean: deletes the /target folder.
  • mvn clean package
  • mvn clean install
  • package: Converts your .java source code into a .jar/.war file and puts it into the /target folder.
  • install: First, it does a package(!). Then it takes that .jar/.war file and puts it into your local Maven repository, which lives in ~/.m2/repository.
  • calling 'mvn install' would be enough if Maven was smart enough to do reliable, incremental builds.
  • figuring out what Java source files/modules changed and only compile those.
  • developers got it ingrained to always call 'mvn clean install' (even though this increases build time a lot in bigger projects).
  • make sure that Maven always tries to download the latest snapshot dependency versions
張 旭

Convert a Standalone to a Replica Set - MongoDB Manual - 0 views

docs.mongodb.com/...vert-standalone-to-replica-set

database mongodb

shared by 張 旭 on 13 Oct 20 - No Cached
  • Restart the instance. Use the --replSet option to specify the name of the new replica set.
  • 張 旭 on 13 Oct 20
     
    "Restart the instance. Use the --replSet option to specify the name of the new replica set. "
張 旭

20 年軟體工程生涯所學到的 20 件事 (摘譯) - Ant ATField - 0 views

blog.gcos.me/...0-years-as-a-software-engineer

architecture programming

shared by 張 旭 on 04 Jun 22 - No Cached
  • 你永遠無法償還所有的技術債、你永遠無法設計出完美的界面、你的測試總是太慢。
  • 這不是一個不把事情做得更好的藉口，而是給你一個視角，不要擔心優雅和完美
  • 有新團隊成員要加入？注意他們在哪裡感到困惑，以及他們問了什麼問題。
  • ...14 more annotations...
  • 軟體是達到目標的手段，而不是目標本身。目標是定向的，但手段要可隨時變通。
  • 不需要維護的程式
  • 10 倍工程師是愚蠢神話。有人能在 1 天內完成另一個有能力、努力工作、有類似經驗的工程師在 2 週內完成的工作，這種想法很愚蠢。
  • 。一個人能夠成為 10 倍工程師的唯一方法，是你把他們和 0.1x 的工程師相比。
  • between a senior engineer and a junior engineer is that they’ve formed opinions about the way things should be
  • 沒有什麼比一個對自己的工具或如何建構軟體沒有意見的資深工程師更讓我擔心了。
  • 如果你正在使用你的工具，而你對它們不愛也不恨，那麼你需要去體驗更多。
  • 你的資料可能會比你的程式長壽。花點精力保持秩序和乾淨
  • 存活下來的老技術是鯊魚，不是恐龍。
  • 軟體工程師應該定期撰寫部落格、日記、文件，總之做任何需要他們保持書面溝通能力之事。
  • 如果你把一個人從他們的工作成果中抽離，他們就會對他們的工作不那麼關心。這也是跨職能團隊運作良好的主要原因，也是 DevOps 變得如此流行的原因。從頭到尾擁有整個過程，並直接負責交付價值。讓一群充滿熱情的人對設計、建構和交付一個軟體 (或任何東西) 擁有完全的自主，這終將發生令人驚奇之事。
  • 面試最好是用來瞭解某人是誰，以及他們對某一專業領域的興趣如何。嘗試找出他們會成為多好的團隊成員是一個沒有結果的努力。
  • 你在建構一個系統的過程中會學到很多東西，你最終會迭代成一個比你當初設計的更好的系統。
  • stop sharpening the saw, and just start cutting shit
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