Imagine that your codebase get a little better everyday. It can if you (and your teammates) apply The Boy Scout Rule.

1. The Boy Scout Rule
Alistair McKinnell
@amckinnell
Nulogy

3. Imagine that your
codebase gets a little
better everyday

4. It’s up to you

5. It’s up to you
(and your teammates)

6. The Boy Scout Rule

7. Always check a module
in cleaner than when
you checked it out

8. KnowYour Language

9. def apply_other_filters(params)
case params[:has_production]
when "yes"
conditions = ["produced_uom > 0"]
when "no"
conditions = ["produced_uom = 0"]
else
conditions = []
end
conditions
end

10. def apply_other_filters(params)
case params[:has_production]
when "yes"
conditions = ["produced_uom > 0"]
when "no"
conditions = ["produced_uom = 0"]
else
conditions = []
end
conditions
end
conditions
conditions
conditions
conditions

11. def apply_other_filters(params)
case params[:has_production]
when "yes"
["produced_uom > 0"]
when "no"
["produced_uom = 0"]
else
[]
end
end

12. def get_number_of_lines
reader = open_csv_reader
reader.shift
lines = 0
reader.each do |row|
lines += 1
end
lines
end

13. def get_number_of_lines
reader = open_csv_reader
reader.shift
lines = 0
reader.each do |row|
lines += 1
end
lines
end
lines = 0
reader.each do |row|
lines += 1
end
lines

14. def get_number_of_lines
reader = open_csv_reader
reader.shift
end
reader.count

15. def repeat_commas(length)
str = ""
length.times { |i| str << ',' }
str
end

16. def repeat_commas(length)
str = ""
length.times { |i| str << ',' }
str
end
str
str
str

17. def repeat_commas(length)
(1..length).map { ',' }.join
end

18. def repeat_commas(length)
',' * length
end

19. ',' * length

20. def create
@organization =
Organization.new(org_params)
validate_org :new
end
def update
load_organization
@organization.attributes = org_params
validate_org :edit
end

21. def create
@organization =
Organization.new(org_params)
validate_org :new
end
def update
load_organization
@organization.attributes = org_params
validate_org :edit
end
validate_org :new
validate_org :edit

22. validate_org(failure_action: :new)
validate_org(failure_action: :edit)
def create
@organization =
Organization.new(org_params)
end
def update
load_organization
@organization.attributes = org_params
end

23. def assign_attributes(product, container)
product.code = container.code
product.desc = container.desc
product.identifier = container.identifier
product
end

24. def assign_attributes(product, container)
product.code = container.code
product.desc = container.desc
product.identifier = container.identifier
product
end
product
product
product
product

25. def assign_attributes(product, container)
product.code = container.code
product.desc = container.desc
product.identifier = container.identifier
product
end
def assign_attributes(product, container)
product.tap do |p|
p.code = container.code
p.desc = container.desc
p.identifier = container.identifier
end
end
product
product
product
product
product.tap

26. def assign_attributes(product, container)
product.code = container.code
product.desc = container.desc
product.identifier = container.identifier
product
end
def assign_attributes(product, container)
product.tap do |p|
p.code = container.code
p.desc = container.desc
p.identifier = container.identifier
end
end

27. KnowYour Language

28. expect(po_item.due).to eq(time('15-01-01'))
expect(po_item.price_per_unit).to eq(19)
expect(po_item.quantity).to eq(14)

29. expect(po_item.due).to eq(time('15-01-01'))
expect(po_item.price_per_unit).to eq(19)
expect(po_item.quantity).to eq(14)
po_item
po_item
po_item

30. expect(po_item.due).to eq(time('15-01-01'))
expect(po_item.price_per_unit).to eq(19)
expect(po_item.quantity).to eq(14)
expect(po_item).to have_attributes(
due: time('15-01-01'),
price_per_unit: 19,
quantity: 14
)
po_item
po_item
po_item
po_item

31. expect(po_item.due).to eq(time('15-01-01'))
expect(po_item.price_per_unit).to eq(19)
expect(po_item.quantity).to eq(14)
expect(po_item).to have_attributes(
due: time('15-01-01'),
price_per_unit: 19,
quantity: 14
)

32. KnowYour Library

33. def serializer
DEPENDENCIES[type][:serializer]
end

34. def serializer
DEPENDENCIES[type][:serializer]
end
[:serializer]

35. def serializer
DEPENDENCIES[type]
end
.fetch(:serializer)

36. Fail Fast

37. def number
"#{order.number}-#{order_item.number}"
end

39. Remove Dead Code

40. The Boy Scout Rule

41. Always check a module
in cleaner than when
you checked it out

42. KnowYour Language
KnowYour Library
Fail Fast
Remove Dead Code

43. When I look at my code
from six months ago
I expect to see ways to
improve it

44. Put your learning and
understanding back
into the code

47. It’s up to you