Lessons learned using Ruby

• Method lookup
• Complex regular expressions
• Exceptions
• Memoization in accessors
• &:symbol - Symbol to Proc / &Proc - Proc to Block / Block to Proc
• dup vs. clone
• Enumerator and Enumerable
• Docker
• Rubocop
• SQL - PostgreSQL
• Setup Ruby in VSCode

Method lookup

Complex regular expressions

Use regex literals with the x option:

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%r{
    <regex_part_1> # you can add comments
    <regex_part_2> # and end of lines
}x

Exceptions

• rescue without a class will capture StandardError and its children.

  • It won’t capture Ruby internal errors, which is fine most of the time.

• raise with no current exception in $! will raise a RuntimeError (which is a child of StandardError).

Docs: https://docs.ruby-lang.org/en/master/Exception.html

Memoization in accessors

• Use memoization in accessors when needed.

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  def some_attribute
    @some_attribute ||= some_network_call
  end
  

  To avoid calling the network again if the first time it returned nil or false:

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  def some_attribute
    return @some_attribute if defined? @some_attribute
    @some_attribute = some_network_call
  end
  

• To avoid making your code unreadable, use gems that do memoization for you.

Docs: https://www.justinweiss.com/articles/4-simple-memoization-patterns-in-ruby-and-one-gem/

&:symbol - Symbol to Proc / &Proc - Proc to Block / Block to Proc

Look at these specs:

https://github.com/hamax97/hamax97.github.io/blob/398236cc6f9e4cb4ebae46f36ce8fb94e2b818fb/write-ups/ruby/%26_operator_with_procs.rb#L1-L37

dup vs. clone

Look at these specs:

https://github.com/hamax97/hamax97.github.io/blob/29c070c534a5489b765af7ec4f79a1db572b9ff7/write-ups/ruby/dup_vs_clone.rb#L1-L94

Enumerator and Enumerable

TODO: Complete this.

Docker

Create a container to test things:

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docker run --rm -it -h myruby --name myruby -v $(pwd):/myapp ruby:3.2.0 /bin/bash

Rubocop

To disable cops or entire departments in specific places of your codebase:

• Disable in a section of code:

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# rubocop:disable Layout/LineLength, Style
[..]
# rubocop:enable Layout/LineLength, Style

• Disable all cops in a section of code:

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# rubocop:disable all
[..]
# rubocop:enable all

• Disable cops or departments in a single line:

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for x in (0..10) # rubocop:disable Style/For

• Disable cops or departments using the .rubocop.yml file:

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Style/StringLiterals:
  Enabled: false

AllCops:
  Exclude:
    - 'docs/**/'

SQL - PostgreSQL

Spin up a container with PostgreSQL:

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docker run --name mypostgresql -d -p 15432:5432 -v mypostgresql:/var/lib/postgresql/data -e POSTGRES_HOST_AUTH_METHOD=trust postgres

Setup Ruby in VSCode

Extensions:

• vscode-ruby by Peng Lv.
• Ruby Solargraph by Castwide.
• Rails Run Specs by Peter Negrei.
• Go to Spec by Lourenci.
• Endiwse.
• ERB Linter.
• ESLint (for JavaScript code).
• Auto Close Tag.
• Github Theme.
• Material Theme Icons.
• vscode-gemfile.
• Ruby Test Explorer.
• Trailing Spaces.
• Auto Markdown TOC.
• VSCode vim, or VSCode Neovim.
• TODO: For debugging?

Gems:

• bundler
• solargraph
• rubocop

Generate solargraph default config file:

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bundle exec solargraph config

Settings file .vscode/settings.json:

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{
    "solargraph.useBundler": true,
    "solargraph.checkGemVersion": false,
    "ruby.lint": {
        "rubocop": {
            "useBundler": true
        }
    },
    "ruby.format": "rubocop",
    "ruby.useBundler": true,
    "auto-close-tag.disableOnLanguage": ["markdown"],
    "ruby.specCommand": "bin/rspec",
    "ruby.specFocusTerminal": false,
    "ruby.specSaveFile": true,
    "markdown-toc.depthFrom": 2,
    "files.insertFinalNewline": true
}

Key shortcuts:

• Go to Spec extension:
  • Go to spec of file: Ctrl + Shift + T.
• Rails Run Specs extension:
  • Run All Specs: Ctrl + Windows + r.
  • Run File Specs: Ctrl + Windows + t.
  • Run Spec Line: Ctrl + Windows + l.
  • Run Last Spec: Ctrl + Windows + y.