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aly quey
aly quey

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Simple memorization

#ruby #beginners

I know ||=, but I have to know more feature of this.

  • Simple simple 
class Smile attr_accessor :smile def ensmile @smile = "SMILE" end end
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  • Use memo simply 
class Smile attr_accessor :smile def ensmile @smile ||= "SMILE" end end
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  • TEST With begin 1) 
class Smile attr_accessor :smile def ensmile @smile ||= begin "SMILE" end end end
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  • TEST With begin 2) 
class Smile attr_accessor :smile def ensmile(cry: false) @smile ||= begin cry ? "CRY" : "SMILE" end end end
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  • TEST includes handling error 
class Smile SmileError = Class.new(StandardError) attr_accessor :smile def ensmile(cry: false) @smile ||= begin raise SmileError if cry "SMILE" rescue SmileError "CRY" end end end
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  • Spec file 
require 'spec_helper' require_relative '../lib/smile' RSpec.describe Smile do let(:smile) { described_class.new } describe '#ensmile' do it 'returns "SMILE"' do expect(smile.smile).to be_nil expect(smile.ensmile).to eq 'SMILE' expect(smile.smile).to eq 'SMILE' end it 'returns "CRY"' do expect(smile.smile).to be_nil expect(smile.ensmile(cry: true)).to eq 'CRY' expect(smile.smile).to eq 'CRY' end end end
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repo: https://github.com/shtakai/simple-smile

Top comments (2)

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jakebman profile image
jakebman •

(Disclaimer - I've never written Ruby, but I'm assuming || is logical or - a || b is a if a is true, otherwise b)

I believe that ||= might not work very well if you try to memoize false.

The point of memoization is that once a value is set, you don't change it:

it 'smilers never "CRY"' do expect(smile.smile).to be_nil expect(smile.ensmile).to eq 'SMILE' expect(smile.ensmile(cry: true)).to eq 'SMILE' expect(smile.smile).to eq 'SMILE' end it 'criers never "SMILE"' do expect(smile.smile).to be_nil expect(smile.ensmile(cry: true)).to eq 'CRY' expect(smile.ensmile).to eq 'CRY' expect(smile.smile).to eq 'CRY' end

Consider a boolean property instead:

class Smile attr_accessor :smiling def ensmile(cry: false) @smiling ||= begin !cry end end end

And test that criers never smile:

it 'criers never "SMILE"' do expect(smile.smiling).to be_nil expect(smile.ensmile(cry: true)).to eq false expect(smile.ensmile).to eq false # Failure here expect(smile.smiling).to eq false # And here, for the same reason end
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alyson profile image
Comment marked as low quality/non-constructive by the community. View Code of Conduct
aly quey •

thank you. I'll check and fix.😃

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