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Don’t Hang Me Out
to DRY
Kevin Murphy
@kevin_j_m
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Don’t Hang Me Out
to DRY
Kevin Murphy
@kevin_j_m
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@kevin_j_m
vory Tower
nnovation TechnologY
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@kevin_j_m
T
T
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@kevin_j_m
T
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@kevin_j_m
T
our code has
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@kevin_j_m
T
Make work
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@kevin_j_m
T
Make work
☂
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@kevin_j_m
T
Make
T
work
Make right
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@kevin_j_m
T
Make right
❌
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@kevin_j_m
T
Make
T
T
work
Make
Make
right
fast
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@kevin_j_m
T
Make fast
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@kevin_j_m
T
Make
T
T
work
Make
Make
right
fast
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@kevin_j_m
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No content
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@kevin_j_m
Kevin Murphy
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@kevin_j_m
T
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@kevin_j_m
Should see 4 testimonials
today, but only 3 are seen.
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@kevin_j_m
def number_testimonials
if mercury_retrograde?
4
elsif full_moon?
3
elsif tuesday?
2
else
coin_flip
end
end
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@kevin_j_m
def number_testimonials
if mercury_retrograde?
4
elsif full_moon?
3
elsif tuesday?
2
else
coin_flip
end
end
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@kevin_j_m
Farmer’s Almanac
Mercury in Retrograde
OCT
31
NOV
20
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@kevin_j_m
Code Coverage
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@kevin_j_m
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@kevin_j_m
it "shows 4 testimonials if mercury is in retrograde" do
end
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@kevin_j_m
it "shows 4 testimonials if mercury is in retrograde" do
allow(Mercury).to receive(:in_retrograde?).and_return(true)
end
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@kevin_j_m
it "shows 4 testimonials if mercury is in retrograde" do
allow(Mercury).to receive(:in_retrograde?).and_return(true)
display = TestimonialDisplay.new
end
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@kevin_j_m
it "shows 4 testimonials if mercury is in retrograde" do
allow(Mercury).to receive(:in_retrograde?).and_return(true)
display = TestimonialDisplay.new
expect(display.number_testimonials).to eq 4
end
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@kevin_j_m
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@kevin_j_m
class Mercury
def self.in_retrograde?(date)
end
end
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@kevin_j_m
class Mercury
def self.in_retrograde?(date)
false
end
end
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@kevin_j_m
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@kevin_j_m
Coverage is insufficient
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@kevin_j_m
TDD
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@kevin_j_m
Pair Programming
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@kevin_j_m
Mutation Testing
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@kevin_j_m
Code Review
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@kevin_j_m
QA
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@kevin_j_m
'
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@kevin_j_m
Coverage is insufficient
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@kevin_j_m
Coverage as a goal
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@kevin_j_m
Randomized with seed 46917
.F..
Failures:
1) TestimonialDisplay#number_testimonials will show 0 or 1 testimonial
if no other conditions are met
Failure/Error: expect(results.uniq).to match_array [0, 1]
expected collection contained: [0, 1]
actual collection contained: [1]
the missing elements were: [0]
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@kevin_j_m
def number_testimonials
if mercury_retrograde?
4
elsif full_moon?
3
elsif tuesday?
2
else
coin_flip
end
end
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@kevin_j_m
def coin_flip
rand(2)
end
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@kevin_j_m
it "will show 0 or 1 testimonial" do
end
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@kevin_j_m
it "will show 0 or 1 testimonial" do
waning_monday = Date.new(2019, 9, 16)
end
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@kevin_j_m
it "will show 0 or 1 testimonial" do
waning_monday = Date.new(2019, 9, 16)
results = []
end
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@kevin_j_m
it "will show 0 or 1 testimonial" do
waning_monday = Date.new(2019, 9, 16)
results = []
display = TestimonialDisplay.new
end
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@kevin_j_m
it "will show 0 or 1 testimonial" do
waning_monday = Date.new(2019, 9, 16)
results = []
display = TestimonialDisplay.new
travel_to waning_monday do
end
end
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@kevin_j_m
it "will show 0 or 1 testimonial" do
waning_monday = Date.new(2019, 9, 16)
results = []
display = TestimonialDisplay.new
travel_to waning_monday do
2.times do
end
end
end
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@kevin_j_m
it "will show 0 or 1 testimonial" do
waning_monday = Date.new(2019, 9, 16)
results = []
display = TestimonialDisplay.new
travel_to waning_monday do
2.times do
results << display.number_testimonials
end
end
end
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@kevin_j_m
it "will show 0 or 1 testimonial" do
waning_monday = Date.new(2019, 9, 16)
results = []
display = TestimonialDisplay.new
travel_to waning_monday do
2.times do
results << display.number_testimonials
end
end
expect(results.uniq).to match_array [0, 1]
end
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@kevin_j_m
it "will show 0 or 1 testimonial" do
waning_monday = Date.new(2019, 9, 16)
results = []
display = TestimonialDisplay.new
travel_to waning_monday do
2.times do
results << display.number_testimonials
end
end
expect(results.uniq).to match_array [0, 1]
end
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@kevin_j_m
it "will show 0 or 1 testimonial" do
waning_monday = Date.new(2019, 9, 16)
results = []
display = TestimonialDisplay.new
travel_to waning_monday do
2.times do
results << display.number_testimonials
end
end
expect(results.uniq).to match_array [0, 1]
end
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@kevin_j_m
it "will show 0 or 1 testimonial" do
waning_monday = Date.new(2019, 9, 16)
results = []
display = TestimonialDisplay.new
travel_to waning_monday do
200.times do
results << display.number_testimonials
end
end
expect(results.uniq).to match_array [0, 1]
end
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@kevin_j_m
it "will show 0 or 1 testimonial" do
waning_monday = Date.new(2019, 9, 16)
display = TestimonialDisplay.new
travel_to waning_monday do
expect(results.uniq).to be_in [0, 1]
end
end
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@kevin_j_m
Vanity metric?
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@kevin_j_m
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@kevin_j_m
Coverage is a signal
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@kevin_j_m
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@kevin_j_m
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@kevin_j_m
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@kevin_j_m
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@kevin_j_m
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@kevin_j_m
Coverage Consideration
Total Cost of Ownership
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@kevin_j_m
T
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@kevin_j_m
+
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@kevin_j_m
☑
Dark Dungeon API Access Keys
should follow same convention
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@kevin_j_m
it "does not provide a company key" do
end
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@kevin_j_m
it "does not provide a company key" do
generator = AccessKeyGenerator.new
end
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@kevin_j_m
it "does not provide a company key" do
generator = AccessKeyGenerator.new
key = generator.access_key(accessor: :user, user_id: 0)
end
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@kevin_j_m
it "does not provide a company key" do
generator = AccessKeyGenerator.new
key = generator.access_key(accessor: :user, user_id: 0)
expect(key.match?(COMPANY_REGEX)).not_to eq true
end
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@kevin_j_m
it "appends the user id if the user's id is odd" do
generator = AccessKeyGenerator.new
key = generator.access_key(accessor_type: :user, user_id: 1)
expect(key).to end_with("-1")
end
it "does not provide a company key" do
generator = AccessKeyGenerator.new
key = generator.access_key(accessor: :user, user_id: 0)
expect(key.match?(COMPANY_REGEX)).not_to eq true
end
it "raises an exception if it doesn't understand the accessor type" do
generator = AccessKeyGenerator.new
expect { generator.access_key(accessor_type: :foo) }
.to raise_error UnknownAccessorType
end
end
end
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@kevin_j_m
it "appends the user id if the user's id is odd" do
generator = AccessKeyGenerator.new
key = generator.access_key(accessor_type: :user, user_id: 1)
expect(key).to end_with("-1")
end
it "does not provide a company key" do
generator = AccessKeyGenerator.new
key = generator.access_key(accessor: :user, user_id: 0)
expect(key.match?(COMPANY_REGEX)).not_to eq true
end
it "raises an exception if it doesn't understand the accessor type" do
generator = AccessKeyGenerator.new
expect { generator.access_key(accessor_type: :foo) }
.to raise_error UnknownAccessorType
end
end
end
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@kevin_j_m
RSpec.describe AccessKeyGenerator do
UUID_REGEX = /[0-9a-fA-F]{8}\-[0-9a-fA-F]{4}\-[0-9a-fA-F]{4}\-[0-9a-fA-F]{4}\-[0-9a-fA-F]{12}/
COMPANY_REGEX = /CO-[0-9a-fA-F]{8}/
describe "#access_key" do
it "provides a base-64 encoded key if the key is for an acquired company" do
generator = AccessKeyGenerator.new
key = generator.access_key(accessor_type: :company, acquired_company: true)
expect(key).to eq Base64.strict_encode64(Base64.decode64(key))
end
it "creates an ivory tower company access key if it's a company not acquired" do
generator = AccessKeyGenerator.new
key = generator.access_key(accessor_type: :company, acquired_company: false)
expect(key.match?(COMPANY_REGEX)).to eq true
end
it "does not provide a full UUID if the key is for a company" do
generator = AccessKeyGenerator.new
key = generator.access_key(accessor_type: :company)
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@kevin_j_m
RSpec.describe AccessKeyGenerator do
UUID_REGEX = /[0-9a-fA-F]{8}\-[0-9a-fA-F]{4}\-[0-9a-fA-F]{4}\-[0-9a-fA-F]{4}\-[0-9a-fA-F]{12}/
COMPANY_REGEX = /CO-[0-9a-fA-F]{8}/
describe "#access_key" do
it "provides a base-64 encoded key if the key is for an acquired company" do
generator = AccessKeyGenerator.new
key = generator.access_key(accessor_type: :company, acquired_company: true)
expect(key).to eq Base64.strict_encode64(Base64.decode64(key))
end
it "creates an ivory tower company access key if it's a company not acquired" do
generator = AccessKeyGenerator.new
key = generator.access_key(accessor_type: :company, acquired_company: false)
expect(key.match?(COMPANY_REGEX)).to eq true
end
it "does not provide a full UUID if the key is for a company" do
generator = AccessKeyGenerator.new
key = generator.access_key(accessor_type: :company)
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@kevin_j_m
DRY Code
Don’t Repeat Yourself
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@kevin_j_m
DAMP Code
Descriptive And Meaningful
Phrases
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@kevin_j_m
it "does not provide a company key" do
generator = AccessKeyGenerator.new
key = generator.access_key(accessor: :user, user_id: 0)
expect(key.match?(COMPANY_REGEX)).not_to eq true
end
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@kevin_j_m
it "does not provide a company key" do
company_regex = /CO-[0-9a-fA-F]{8}/
generator = AccessKeyGenerator.new
key = generator.access_key(accessor: :user, user_id: 0)
expect(key.match?(COMPANY_REGEX)).not_to eq true
end
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@kevin_j_m
it "does not provide a company key" do
company_regex = /CO-[0-9a-fA-F]{8}/
generator = AccessKeyGenerator.new
key = generator.access_key(accessor: :user, user_id: 0)
expect(key.match?(company_regex)).not_to eq true
end
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@kevin_j_m
T
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@kevin_j_m
class AccessKeyGenerator
def access_key(accessor:, user_id: nil)
if accessor == :company
"CO-#{SecureRandom.hex(8)}"
elsif accessor == :user
uuid = SecureRandom.uuid
user_id.odd? ? uuid << “-#{user_id}" : uuid
end
end
end
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@kevin_j_m
class AccessKeyGenerator
def access_key(accessor:, acquired_co: nil, user_id: nil)
if accessor == :company
"CO-#{SecureRandom.hex(8)}"
elsif accessor == :user
uuid = SecureRandom.uuid
user_id.odd? ? uuid << “-#{user_id}" : uuid
end
end
end
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@kevin_j_m
class AccessKeyGenerator
def access_key(accessor:, acquired_co: nil, user_id: nil)
if accessor == :company
if acquired_co
SecureRandom.base64
else
“CO-#{SecureRandom.hex(8)}”
end
elsif accessor == :user
uuid = SecureRandom.uuid
user_id.odd? ? uuid << “-#{user_id}" : uuid
end
end
end
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@kevin_j_m
DRY Code?
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@kevin_j_m
class User < ApplicationRecord
def generate_access_key
SecureRandom.uuid
end
end
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@kevin_j_m
class Company < ApplicationRecord
def generate_access_key
SecureRandom.uuid
end
end
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@kevin_j_m
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@kevin_j_m
class AccessKeyGenerator
def access_key
SecureRandom.uuid
end
end
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@kevin_j_m
class AccessKeyGenerator
def access_key(accessor:, user_id: nil)
if accessor == :company
"CO-#{SecureRandom.hex(8)}"
elsif accessor == :user
uuid = SecureRandom.uuid
user_id.odd? ? uuid << “-#{user_id}" : uuid
end
end
end
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@kevin_j_m
WET Code
Write Everything Twice
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@kevin_j_m
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@kevin_j_m
class User < ApplicationRecord
def generate_access_key
SecureRandom.uuid
end
end
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@kevin_j_m
class User < ApplicationRecord
def generate_access_key
SecureRandom.uuid
end
end
class Company < ApplicationRecord
def generate_access_key
SecureRandom.uuid
end
end
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@kevin_j_m
class User < ApplicationRecord
def generate_access_key
if id.odd?
"#{SecureRandom.uuid}-#{id}"
else
SecureRandom.uuid
end
end
end
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@kevin_j_m
class User < ApplicationRecord
def generate_access_key
if id.odd?
"#{SecureRandom.uuid}-#{id}"
else
SecureRandom.uuid
end
end
end
class Company < ApplicationRecord
def generate_access_key
if acquisition?
SecureRandom.base64
else
"CO-#{SecureRandom.hex(8)}"
end
end
end
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@kevin_j_m
DRY Consideration
Flexibility
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@kevin_j_m
T
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@kevin_j_m
Passing “15” to API
provides wrong result
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@kevin_j_m
Performant Code
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@kevin_j_m
Rust
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@kevin_j_m
gem 'helix-rails', '~> 0.5.0'
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@kevin_j_m
def generate(bound: i32)
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@kevin_j_m
def generate(bound: i32) -> Vec {
}
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@kevin_j_m
def generate(bound: i32) -> Vec {
let mut results = Vec::new();
}
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@kevin_j_m
def generate(bound: i32) -> Vec {
let mut results = Vec::new();
for x in 1..(bound+1) {
}
}
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@kevin_j_m
def generate(bound: i32) -> Vec {
let mut results = Vec::new();
for x in 1..(bound+1) {
results.push(match(x % 3, x % 5) {
})
}
}
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@kevin_j_m
def generate(bound: i32) -> Vec {
let mut results = Vec::new();
for x in 1..(bound+1) {
results.push(match(x % 3, x % 5) {
(0, 0) => "FizzBuzz".to_string(),
})
}
}
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@kevin_j_m
def generate(bound: i32) -> Vec {
let mut results = Vec::new();
for x in 1..(bound+1) {
results.push(match(x % 3, x % 5) {
(0, 0) => "FizzBuzz".to_string(),
(0, _) => "Fizz".to_string(),
})
}
}
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@kevin_j_m
def generate(bound: i32) -> Vec {
let mut results = Vec::new();
for x in 1..(bound+1) {
results.push(match(x % 3, x % 5) {
(0, 0) => "FizzBuzz".to_string(),
(0, _) => "Fizz".to_string(),
(_, 0) => "Buzz".to_string(),
})
}
}
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@kevin_j_m
def generate(bound: i32) -> Vec {
let mut results = Vec::new();
for x in 1..(bound+1) {
results.push(match(x % 3, x % 5) {
(0, 0) => "FizzBuzz".to_string(),
(0, _) => "Fizz".to_string(),
(_, 0) => "Buzz".to_string(),
(2, 4) => "Buzz".to_string(),
})
}
}
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@kevin_j_m
def generate(bound: i32) -> Vec {
let mut results = Vec::new();
for x in 1..(bound+1) {
results.push(match(x % 3, x % 5) {
(0, 0) => "FizzBuzz".to_string(),
(0, _) => "Fizz".to_string(),
(_, 0) => "Buzz".to_string(),
(2, 4) => "Buzz".to_string(),
(_, _) => x.to_string(),
})
}
}
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@kevin_j_m
def generate(bound: i32) -> Vec {
let mut results = Vec::new();
for x in 1..(bound+1) {
results.push(match(x % 3, x % 5) {
(0, 0) => "FizzBuzz".to_string(),
(0, _) => "Fizz".to_string(),
(_, 0) => "Buzz".to_string(),
(2, 4) => "Buzz".to_string(),
(_, _) => x.to_string(),
})
}
results
}
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@kevin_j_m
FBAAS
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@kevin_j_m
FBAAS
FizzBuzz As A Service
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@kevin_j_m
def generate(bound: i32) -> Vec {
let mut results = Vec::new();
for x in 1..(bound+1) {
results.push(match(x % 3, x % 5) {
(0, 0) => "FizzBuzz".to_string(),
(0, _) => "Fizz".to_string(),
(_, 0) => "Buzz".to_string(),
(2, 4) => "Buzz".to_string(),
(_, _) => x.to_string(),
})
}
results
}
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@kevin_j_m
def generate(bound: i32) -> Vec {
let mut results = Vec::new();
for x in 1..(bound+1) {
results.push(match(x % 3, x % 5) {
(0, 0) => "FizzBuzz".to_string(),
(0, _) => "Fizz".to_string(),
(_, 0) => "Buzz".to_string(),
(2, 4) => "Buzz".to_string(),
(_, _) => x.to_string(),
})
}
results
}
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@kevin_j_m
def generate(bound: i32) -> Vec {
let mut results = Vec::new();
for x in 1..(bound+1) {
results.push(match(x % 3, x % 5) {
(0, 0) => "FizzBuzz".to_string(),
(0, _) => "Fizz".to_string(),
(_, 0) => "Buzz".to_string(),
(_, _) => x.to_string(),
})
}
results
}
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@kevin_j_m
Performant Consideration
Weigh observed behavior &
maintenance
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@kevin_j_m
T
Make
T
T
work
Make
Make
right
fast
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@kevin_j_m
T
Make work
for confidence,
not metrics
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@kevin_j_m
T
Make right
knowing “right”
is subjective
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@kevin_j_m
T
Make fast
when you know
it’s warranted
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@kevin_j_m
https://www.thegnar.co/rubyconf
https://github.com/kevin-j-m/ivory-tower
T
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@kevin_j_m
https://www.thegnar.co/rubyconf