3. First Do No Harm: Surgical Refactoring @nellshamrell
Refactoring is a change
and changes can go wrong
What is refactoring?
4. But…it’s not life or death, right?
First Do No Harm: Surgical Refactoring @nellshamrell
5. But…it’s not life or death, right?
First Do No Harm: Surgical Refactoring @nellshamrell
Software is being integrated into…
6. But…it’s not life or death, right?
First Do No Harm: Surgical Refactoring @nellshamrell
Software is being integrated into…
Transportation
7. But…it’s not life or death, right?
First Do No Harm: Surgical Refactoring @nellshamrell
Software is being integrated into…
Transportation
Energy sources
8. But…it’s not life or death, right?
First Do No Harm: Surgical Refactoring @nellshamrell
Software is being integrated into…
Transportation
Energy sources
Medical Devices
10. So…is refactoring bad, then?
First Do No Harm: Surgical Refactoring @nellshamrell
Refactoring is neither inherently good OR bad
11. So…is refactoring bad, then?
First Do No Harm: Surgical Refactoring @nellshamrell
How you do it is what matters
12. How should I refactor?
First Do No Harm: Surgical Refactoring @nellshamrell
2 Common Approaches
13. How should I refactor?
First Do No Harm: Surgical Refactoring @nellshamrell
2 Common Approaches
1) Edit and Pray
14. How should I refactor?
First Do No Harm: Surgical Refactoring @nellshamrell
2 Common Approaches
1) Edit and Pray
2) Cover and Modify
15. How should I refactor?
First Do No Harm: Surgical Refactoring @nellshamrell
2 Common Approaches
1) Edit and Pray
2) Cover and Modify
- “Working Effectively with Legacy Code”
17. What is surgical refactoring?
First Do No Harm: Surgical Refactoring @nellshamrell
Change exactly what we INTEND to change
And ONLY what we intend to change
18. What is surgical refactoring?
First Do No Harm: Surgical Refactoring @nellshamrell
First do no harm!
19. First Do No Harm: Surgical Refactoring @nellshamrell
Surgical refactoring is a series of
good habits that reduce risk
What is surgical refactoring?
20. First Do No Harm: Surgical Refactoring @nellshamrell
2 categories of refactoring
What is surgical refactoring?
21. First Do No Harm: Surgical Refactoring @nellshamrell
2 categories of refactoring
What is surgical refactoring?
1) Necessary refactoring
22. First Do No Harm: Surgical Refactoring @nellshamrell
2 categories of refactoring
What is surgical refactoring?
1) Necessary refactoring
2) Cosmetic refactoring
23. What is a necessary refactoring?
First Do No Harm: Surgical Refactoring @nellshamrell
Need to add something
24. What is a necessary refactoring?
First Do No Harm: Surgical Refactoring @nellshamrell
Need to add something
Code is too inefficient
25. What is a necessary refactoring?
First Do No Harm: Surgical Refactoring @nellshamrell
Need to add something
Code is too inefficient
Blocked from achieving a business need
26. What is a necessary refactoring?
First Do No Harm: Surgical Refactoring @nellshamrell
Necessary refactorings have a
moderate to high risk tolerance
27. What is a cosmetic refactoring?
First Do No Harm: Surgical Refactoring @nellshamrell
28. What is a cosmetic refactoring?
First Do No Harm: Surgical Refactoring @nellshamrell
No business need to change code
29. What is a cosmetic refactoring?
First Do No Harm: Surgical Refactoring @nellshamrell
Something about it just bugs us
No business need to change code
30. What is a cosmetic refactoring?
First Do No Harm: Surgical Refactoring @nellshamrell
Cosmetic refactorings
have a low risk tolerance
31. What about whitespace refactoring?
First Do No Harm: Surgical Refactoring @nellshamrell
32. What about whitespace refactoring?
First Do No Harm: Surgical Refactoring @nellshamrell
Ultimate cosmetic refactoring
33. What about whitespace refactoring?
First Do No Harm: Surgical Refactoring @nellshamrell
Ultimate cosmetic refactoring
Get a style guide
(i.e. Github style guide)
34. What about whitespace refactoring?
First Do No Harm: Surgical Refactoring @nellshamrell
Ultimate cosmetic refactoring
Get a style guide
(i.e. Github style guide)
If whitespace does not violate style
guide, leave it alone!
35. What’s involved in surgical refactoring?
First Do No Harm: Surgical Refactoring @nellshamrell
36. What’s involved in surgical refactoring?
First Do No Harm: Surgical Refactoring @nellshamrell
1) Pre-op: what to do before touching the code
37. What’s involved in surgical refactoring?
First Do No Harm: Surgical Refactoring @nellshamrell
1) Pre-op: what to do before touching the code
2) Operation: doing the actual refactoring
38. What’s involved in surgical refactoring?
First Do No Harm: Surgical Refactoring @nellshamrell
1) Pre-op: what to do before touching the code
2) Operation: doing the actual refactoring
3) Recovery: verifying the refactor
39. First Do No Harm: Surgical Refactoring @nellshamrell
lib/do_system_things.rb
class DoSystemThings
def do_the_thing(dir)
system "sed -E -i '' 's/:([[:alnum:]]+)[[:space:]]=>/1:/g'
#{dir}/**/*.rb"
end
end
Thanks, @mikelorant!
41. What is involved in pre-op?
First Do No Harm: Surgical Refactoring @nellshamrell
Diagnosis
(What exactly does the code do?)
42. First Do No Harm: Surgical Refactoring @nellshamrell
lib/do_system_things.rb
class DoSystemThings
def do_the_thing(dir)
system "sed -E -i '' 's/:([[:alnum:]]+)[[:space:]]=>/1:/g'
#{dir}/**/*.rb"
end
end
43. First Do No Harm: Surgical Refactoring @nellshamrell
lib/do_system_things.rb
class DoSystemThings
def do_the_thing(dir)
system "sed -E -i '' 's/:([[:alnum:]]+)[[:space:]]=>/1:/g'
#{dir}/**/*.rb"
end
end Calls Ruby’s system method
44. First Do No Harm: Surgical Refactoring @nellshamrell
lib/do_system_things.rb
class DoSystemThings
def do_the_thing(dir)
system "sed -E -i '' 's/:([[:alnum:]]+)[[:space:]]=>/1:/g'
#{dir}/**/*.rb"
end
end
Executes sed command with
some flags
45. First Do No Harm: Surgical Refactoring @nellshamrell
lib/do_system_things.rb
class DoSystemThings
def do_the_thing(dir)
system "sed -E -i '' 's/:([[:alnum:]]+)[[:space:]]=>/1:/g'
#{dir}/**/*.rb"
end
end
Performs a substitution
46. First Do No Harm: Surgical Refactoring @nellshamrell
lib/do_system_things.rb
class DoSystemThings
def do_the_thing(dir)
system "sed -E -i '' 's/:([[:alnum:]]+)[[:space:]]=>/1:/g'
#{dir}/**/*.rb"
end
end
In a series directories and files
47. So…do we know what it does?
First Do No Harm: Surgical Refactoring @nellshamrell
48. So…do we know what it does?
First Do No Harm: Surgical Refactoring @nellshamrell
Map is influenced by our own
experiences and expectations
49. So…do we know what it does?
First Do No Harm: Surgical Refactoring @nellshamrell
Only definite way of knowing what the code
does is to execute the code itself
50. So…do we know what it does?
First Do No Harm: Surgical Refactoring @nellshamrell
Best way to repeatedly execute the
code is through automated tests
51. First Do No Harm: Surgical Refactoring @nellshamrell
lib/do_system_things.rb
class DoSystemThings
def do_the_thing(dir)
system "sed -E -i '' 's/:([[:alnum:]]+)[[:space:]]=>/1:/g'
#{dir}/**/*.rb"
end
end
Now what does this
system call do?
52. First Do No Harm: Surgical Refactoring @nellshamrell
spec/do_system_things_spec.rb
let(:do_system_things) { DoSystemThings.new }
Instantiate the class
53. First Do No Harm: Surgical Refactoring @nellshamrell
spec/do_system_things_spec.rb
let(:do_system_things) { DoSystemThings.new }
let(:dir) { ‘something’ }
Sample argument
to pass to class
54. First Do No Harm: Surgical Refactoring @nellshamrell
spec/do_system_things_spec.rb
let(:do_system_things) { DoSystemThings.new }
let(:dir) { ‘something’ }
describe ‘making the system call’ do
it ‘calls the Ruby#system method’ do
end
end
55. First Do No Harm: Surgical Refactoring @nellshamrell
spec/do_system_things_spec.rb
let(:do_system_things) { DoSystemThings.new }
let(:dir) { ‘something’ }
describe ‘making the system call’ do
it ‘calls the Ruby#system method’ do
expect(do_system_things)
.to receive(:system).with(anything())
end
end
Expect that our instance
of the class
56. First Do No Harm: Surgical Refactoring @nellshamrell
spec/do_system_things_spec.rb
Will receive a system call
with any args
let(:do_system_things) { DoSystemThings.new }
let(:dir) { ‘something’ }
describe ‘making the system call’ do
it ‘calls the Ruby#system method’ do
expect(do_system_things)
.to receive(:system).with(anything())
end
end
57. First Do No Harm: Surgical Refactoring @nellshamrell
spec/do_system_things_spec.rb
let(:do_system_things) { DoSystemThings.new }
let(:dir) { ‘something’ }
describe ‘making the system call’ do
it ‘calls the Ruby#system method’ do
expect(do_system_things)
.to receive(:system).with(anything())
do_system_things.do_the_thing(dir)
end
end
Call the method
58. First Do No Harm: Surgical Refactoring @nellshamrell
spec/do_system_things_spec.rb
let(:do_system_things) { DoSystemThings.new }
let(:dir) { ‘something’ }
describe ‘making the system call’ do
it ‘calls the Ruby#system method’ do
expect(do_system_things)
.to receive(:system).with(anything())
do_system_things.do_the_thing(dir)
end
end
Spec Passes!
59. First Do No Harm: Surgical Refactoring @nellshamrell
lib/do_system_things.rb
class DoSystemThings
def do_the_thing(dir)
"sed -E -i '' 's/:([[:alnum:]]+)[[:space:]]=>/1:/g'
#{dir}/**/*.rb"
end
end
Remove the system call
60. First Do No Harm: Surgical Refactoring @nellshamrell
lib/do_system_things.rb
class DoSystemThings
def do_the_thing(dir)
"sed -E -i '' 's/:([[:alnum:]]+)[[:space:]]=>/1:/g'
#{dir}/**/*.rb"
end
end
Spec Fails!
61. First Do No Harm: Surgical Refactoring @nellshamrell
lib/do_system_things.rb
class DoSystemThings
def do_the_thing(dir)
system "sed -E -i '' 's/:([[:alnum:]]+)[[:space:]]=>/1:/g'
#{dir}/**/*.rb"
end
end
Put the system call back
62. First Do No Harm: Surgical Refactoring @nellshamrell
lib/do_system_things.rb
class DoSystemThings
def do_the_thing(dir)
system "sed -E -i '' 's/:([[:alnum:]]+)[[:space:]]=>/1:/g'
#{dir}/**/*.rb"
end
end
Spec Passes!
63. First Do No Harm: Surgical Refactoring @nellshamrell
lib/do_system_things.rb
class DoSystemThings
def do_the_thing(dir)
system "sed -E -i '' 's/:([[:alnum:]]+)[[:space:]]=>/1:/g'
#{dir}/**/*.rb"
end
end
What return is expected?
64. First Do No Harm: Surgical Refactoring @nellshamrell
lib/do_system_things.rb
class DoSystemThings
def do_the_thing(dir)
system "sed -E -i '' 's/:([[:alnum:]]+)[[:space:]]=>/1:/g'
#{dir}/**/*.rb"
end
end Rdocs: system method returns true
when the command executes
successfully
65. First Do No Harm: Surgical Refactoring @nellshamrell
spec/do_system_things_spec.rb
let(:dir) { ‘something’ }
context ‘when the method call is successful’ do
it ‘returns true’ do
end
end
66. First Do No Harm: Surgical Refactoring @nellshamrell
spec/do_system_things_spec.rb
let(:dir) { ‘something’ }
context ‘when the method call is successful’ do
it ‘returns true’ do
expect(do_system_things.do_the_thing(dir)).to eq(true)
end
end
Expect the return from calling
the method on the instance
of the class
67. First Do No Harm: Surgical Refactoring @nellshamrell
spec/do_system_things_spec.rb
let(:dir) { ‘something’ }
context ‘when the method call is successful’ do
it ‘returns true’ do
expect(do_system_things.do_the_thing(dir)).to eq(true)
end
end
To return true
68. First Do No Harm: Surgical Refactoring @nellshamrell
spec/do_system_things_spec.rb
let(:dir) { ‘something’ }
context ‘when the method call is successful’ do
it ‘returns true’ do
expect(do_system_things.do_the_thing(dir)).to eq(true)
end
end
Spec Fails!
69. First Do No Harm: Surgical Refactoring @nellshamrell
spec/do_system_things_spec.rb
'sed: directory/*/.rb: No such file or directory'
let(:dir) { ‘something’ }
context ‘when the method call is successful’ do
it ‘returns true’ do
expect(do_system_things.do_the_thing(dir)).to eq(true)
end
end
70. First Do No Harm: Surgical Refactoring @nellshamrell
spec/do_system_things_spec.rb
context ‘when the method call is successful’ do
let(:directory_name) { ‘some_directory’ }
let(:sub_directory) { ‘some_sub_directory’ }
let(:file) { ‘some_file.rb’ }
it ‘returns true’ do
expect(do_system_things.do_the_thing(dir)).to eq(true)
end
end
Set the directory, subdirectory, and file names
71. First Do No Harm: Surgical Refactoring @nellshamrell
spec/do_system_things_spec.rb
context ‘when the method call is successful’ do
let(:directory_name) { ‘some_directory’ }
let(:sub_directory) { ‘some_sub_directory’ }
let(:file) { ‘some_file.rb’ }
before do
FileUtils.mkdir_p(File.join(directory_name, sub_directory))
end
it ‘returns true’ do
expect(do_system_things.do_the_thing(dir)).to eq(true)
end
end
Create directories and sub-directories
72. First Do No Harm: Surgical Refactoring @nellshamrell
spec/do_system_things_spec.rb
context ‘when the method call is successful’ do
let(:directory_name) { ‘some_directory’ }
let(:sub_directory) { ‘some_sub_directory’ }
let(:file) { ‘some_file.rb’ }
before do
FileUtils.mkdir_p(File.join(directory_name, sub_directory))
path = File
.join(directory_name,subdirectory_name,file_name)
end
it ‘returns true’ do
expect(do_system_things.do_the_thing(dir)).to eq(true)
end
end
Create the path for
the file
73. First Do No Harm: Surgical Refactoring @nellshamrell
spec/do_system_things_spec.rb
context ‘when the method call is successful’ do
let(:directory_name) { ‘some_directory’ }
let(:sub_directory) { ‘some_sub_directory’ }
let(:file) { ‘some_file.rb’ }
before do
FileUtils.mkdir_p(File.join(directory_name, sub_directory))
path = File
.join(directory_name,subdirectory_name,file_name)
file = File.new(path, ‘w’)
file.write(‘look, there is something in this file’)
file.close
end
it ‘returns true’ do
Create the actual file
74. First Do No Harm: Surgical Refactoring @nellshamrell
spec/do_system_things_spec.rb
context ‘when the method call is successful’ do
let(:directory_name) { ‘some_directory’ }
let(:sub_directory) { ‘some_sub_directory’ }
let(:file) { ‘some_file.rb’ }
before do
FileUtils.mkdir_p(File.join(directory_name, sub_directory))
path = File
.join(directory_name,subdirectory_name,file_name)
file = File.new(path, ‘w’)
file.write(‘look, there is something in this file’)
file.close
end
it ‘returns true’ do
Spec Passes!
75. First Do No Harm: Surgical Refactoring @nellshamrell
spec/do_system_things_spec.rb
context ‘when the method call is successful’ do
let(:directory_name) { ‘some_directory’ }
let(:sub_directory) { ‘some_sub_directory’ }
let(:file) { ‘some_file.rb’ }
before do
FileUtils.mkdir_p(File.join(directory_name, sub_directory))
path = File
.join(directory_name,subdirectory_name,file_name)
file = File.new(path, ‘w’)
file.write(‘look, there is something in this file’)
file.close
end
it ‘returns true’ do That’s a lot of setup code…
76. First Do No Harm: Surgical Refactoring @nellshamrell
spec/do_system_things_spec.rb
def create_required_directories_and_files(path, filename)
FileUtils.mkdir_p(File.join(path))
file = File.new(File.join(path,file_name), ‘w’)
file.write(‘look, there is something in this file’)
file.close
end
Takes a path and
file name
77. First Do No Harm: Surgical Refactoring @nellshamrell
spec/do_system_things_spec.rb
def create_required_directories_and_files(path, filename)
FileUtils.mkdir_p(File.join(path))
file = File.new(File.join(path,file_name), ‘w’)
file.write(‘look, there is something in this file’)
file.close
end
Makes the directories
78. First Do No Harm: Surgical Refactoring @nellshamrell
spec/do_system_things_spec.rb
def create_required_directories_and_files(path, filename)
FileUtils.mkdir_p(File.join(path))
file = File.new(File.join(path,file_name), ‘w’)
file.write(‘look, there is something in this file’)
file.close
end
Makes the file
79. First Do No Harm: Surgical Refactoring @nellshamrell
spec/do_system_things_spec.rb
before do
create_required_directories_and_files(
File.join(directory_name,subdirectory_name), file_name
)
end
it ‘returns true’ do
expect(do_system_things.do_the_thing(dir)).to eq(true)
end
Call the setup
method
80. First Do No Harm: Surgical Refactoring @nellshamrell
spec/do_system_things_spec.rb
before do
create_required_directories_and_files(
File.join(directory_name,subdirectory_name), file_name
)
end
it ‘returns true’ do
expect(do_system_things.do_the_thing(dir)).to eq(true)
end
Create and pass
the path for the file
81. First Do No Harm: Surgical Refactoring @nellshamrell
spec/do_system_things_spec.rb
before do
create_required_directories_and_files(
File.join(directory_name,subdirectory_name), file_name
)
end
it ‘returns true’ do
expect(do_system_things.do_the_thing(dir)).to eq(true)
end
Pass the file name
82. First Do No Harm: Surgical Refactoring @nellshamrell
spec/do_system_things_spec.rb
before do
create_required_directories_and_files(
File.join(directory_name,subdirectory_name), file_name
)
end
it ‘returns true’ do
expect(do_system_things.do_the_thing(dir)).to eq(true)
end
Spec Passes!
83. First Do No Harm: Surgical Refactoring @nellshamrell
spec/do_system_things_spec.rb
before do
create_required_directories_and_files(
File.join(directory_name,subdirectory_name), file_name
)
end
it ‘returns true’ do
expect(do_system_things.do_the_thing(dir)).to eq(true)
end
after do
FileUtils.rm_rf(directory_name)
end
Remove created
directories and file
84. First Do No Harm: Surgical Refactoring @nellshamrell
spec/do_system_things_spec.rb
before do
create_required_directories_and_files(
File.join(directory_name,subdirectory_name), file_name
)
end
it ‘returns true’ do
expect(do_system_things.do_the_thing(dir)).to eq(true)
end
after do
FileUtils.rm_rf(directory_name)
end
Spec Passes!
85. First Do No Harm: Surgical Refactoring @nellshamrell
lib/do_system_things.rb
class DoSystemThings
def do_the_thing(dir)
system "sed -E -i '' 's/:([[:alnum:]]+)[[:space:]]=>/1:/g'
#{dir}/**/*.rb"
end
end
*pause*
86. First Do No Harm: Surgical Refactoring @nellshamrell
lib/do_system_things.rb
class DoSystemThings
def do_the_thing(dir)
system "sed -E -i '' 's/:([[:alnum:]]+)[[:space:]]=>/1:/g'
#{dir}/**/*.rb"
end
end
sed is a streaming text editor
87. First Do No Harm: Surgical Refactoring @nellshamrell
lib/do_system_things.rb
class DoSystemThings
def do_the_thing(dir)
system "sed -E -i '' 's/:([[:alnum:]]+)[[:space:]]=>/1:/g'
#{dir}/**/*.rb"
end
end
88. First Do No Harm: Surgical Refactoring @nellshamrell
lib/do_system_things.rb
Find match for this pattern
s/:([[:alnum:]]+)[[:space:]]=>/1:/g'
89. First Do No Harm: Surgical Refactoring @nellshamrell
lib/do_system_things.rb
Replace it with this pattern
s/:([[:alnum:]]+)[[:space:]]=>/1:/g'
90. First Do No Harm: Surgical Refactoring @nellshamrell
lib/do_system_things.rb
class DoSystemThings
def first_regex_match(string)
end
def do_the_thing(dir)
system "sed -E -i '' 's/:([[:alnum:]]+)[[:space:]]=>/1:/g'
#{dir}/**/*.rb"
end
end
91. First Do No Harm: Surgical Refactoring @nellshamrell
lib/do_system_things.rb
class DoSystemThings
def first_regex_match(string)
//.match(string)
end
def do_the_thing(dir)
system "sed -E -i '' 's/:([[:alnum:]]+)[[:space:]]=>/1:/g'
#{dir}/**/*.rb"
end
end
92. First Do No Harm: Surgical Refactoring @nellshamrell
spec/do_system_things_spec.rb
describe ‘what the regex matches’
# FOR REFERENCE: /:([[:alnum:]]+)[[:space:]]=>/
end
93. First Do No Harm: Surgical Refactoring @nellshamrell
spec/do_system_things_spec.rb
describe ‘what the regex matches’
# FOR REFERENCE: /:([[:alnum:]]+)[[:space:]]=>/
let(:string) {‘'}
end
94. First Do No Harm: Surgical Refactoring @nellshamrell
spec/do_system_things_spec.rb
describe ‘what the regex matches’
# FOR REFERENCE: /:([[:alnum:]]+)[[:space:]]=>/
let(:string) {''}
it 'matches a string' do
end
end
95. First Do No Harm: Surgical Refactoring @nellshamrell
spec/do_system_things_spec.rb
describe ‘what the regex matches’
# FOR REFERENCE: /:([[:alnum:]]+)[[:space:]]=>/
let(:string) {''}
it 'matches a string' do
expect(do_system_things.first_regex_match(string))
.not_to be_nil
end
end
96. First Do No Harm: Surgical Refactoring @nellshamrell
lib/do_system_things.rb
class DoSystemThings
def first_regex_match(string)
//.match(string)
end
def do_the_thing(dir)
system "sed -E -i '' 's/:([[:alnum:]]+)[[:space:]]=>/1:/g'
#{dir}/**/*.rb"
end
end
Returns nil if no successful match
97. First Do No Harm: Surgical Refactoring @nellshamrell
spec/do_system_things_spec.rb
describe ‘what the regex matches’
# FOR REFERENCE: /:([[:alnum:]]+)[[:space:]]=>/
let(:string) {''}
it 'matches a string' do
expect(do_system_things.first_regex_match(string))
.not_to be_nil
end
end
Means it found a successful match
98. First Do No Harm: Surgical Refactoring @nellshamrell
spec/do_system_things_spec.rb
describe ‘what the regex matches’
# FOR REFERENCE: /:([[:alnum:]]+)[[:space:]]=>/
let(:string) {''}
it 'matches a string' do
expect(do_system_things.first_regex_match(string))
.not_to be_nil
end
end
first character is ‘:’
99. First Do No Harm: Surgical Refactoring @nellshamrell
spec/do_system_things_spec.rb
describe ‘what the regex matches’
# FOR REFERENCE: /:([[:alnum:]]+)[[:space:]]=>/
let(:string) {‘:'}
it 'matches a string' do
expect(do_system_things.first_regex_match(string))
.not_to be_nil
end
end
add ‘:’ to string
100. First Do No Harm: Surgical Refactoring @nellshamrell
spec/do_system_things_spec.rb
describe ‘what the regex matches’
# FOR REFERENCE: /:([[:alnum:]]+)[[:space:]]=>/
let(:string) {‘:'}
it 'matches a string' do
expect(do_system_things.first_regex_match(string))
.not_to be_nil
end
end
Spec Fails!
101. First Do No Harm: Surgical Refactoring @nellshamrell
lib/do_system_things.rb
class DoSystemThings
def first_regex_match(string)
/:/.match(string)
end
def do_the_thing(dir)
system "sed -E -i '' 's/:([[:alnum:]]+)[[:space:]]=>/1:/g'
#{dir}/**/*.rb"
end
end
add ‘:’ to regex
102. First Do No Harm: Surgical Refactoring @nellshamrell
lib/do_system_things.rb
class DoSystemThings
def first_regex_match(string)
/:/.match(string)
end
def do_the_thing(dir)
system "sed -E -i '' 's/:([[:alnum:]]+)[[:space:]]=>/1:/g'
#{dir}/**/*.rb"
end
end
Spec Passes!
103. First Do No Harm: Surgical Refactoring @nellshamrell
spec/do_system_things_spec.rb
describe ‘what the regex matches’
# FOR REFERENCE: /:([[:alnum:]]+)[[:space:]]=>/
let(:string) {‘:'}
it 'matches a string' do
expect(do_system_things.first_regex_match(string))
.not_to be_nil
end
end
Next character is alnum
character class
104. First Do No Harm: Surgical Refactoring @nellshamrell
spec/do_system_things_spec.rb
describe ‘what the regex matches’
# FOR REFERENCE: /:([[:alnum:]]+)[[:space:]]=>/
let(:string) {‘:a'}
it 'matches a string' do
expect(do_system_things.first_regex_match(string))
.not_to be_nil
end
end
Add letter to test string
105. First Do No Harm: Surgical Refactoring @nellshamrell
spec/do_system_things_spec.rb
Spec Fails!
describe ‘what the regex matches’
# FOR REFERENCE: /:([[:alnum:]]+)[[:space:]]=>/
let(:string) {‘:a'}
it 'matches a string' do
expect(do_system_things.first_regex_match(string))
.not_to be_nil
end
end
106. First Do No Harm: Surgical Refactoring @nellshamrell
lib/do_system_things.rb
class DoSystemThings
def first_regex_match(string)
/:[[:alnum:]]/.match(string)
end
def do_the_thing(dir)
system "sed -E -i '' 's/:([[:alnum:]]+)[[:space:]]=>/1:/g'
#{dir}/**/*.rb"
end
end
add alnum to regex
107. First Do No Harm: Surgical Refactoring @nellshamrell
lib/do_system_things.rb
class DoSystemThings
def first_regex_match(string)
/:[[:alnum:]]/.match(string)
end
def do_the_thing(dir)
system "sed -E -i '' 's/:([[:alnum:]]+)[[:space:]]=>/1:/g'
#{dir}/**/*.rb"
end
end
Spec Passes!
108. First Do No Harm: Surgical Refactoring @nellshamrell
spec/do_system_things_spec.rb
describe ‘what the regex matches’
# FOR REFERENCE: /:([[:alnum:]]+)[[:space:]]=>/
let(:string) {‘:a'}
it 'matches a string' do
expect(do_system_things.first_regex_match(string))
.not_to be_nil
end
end Means character must
appear one or more times
109. First Do No Harm: Surgical Refactoring @nellshamrell
spec/do_system_things_spec.rb
describe ‘what the regex matches’
# FOR REFERENCE: /:([[:alnum:]]+)[[:space:]]=>/
let(:string) {‘:ab'}
it 'matches a string' do
expect(do_system_things.first_regex_match(string))
.not_to be_nil
end
end
Add character to test string
110. First Do No Harm: Surgical Refactoring @nellshamrell
spec/do_system_things_spec.rb
Spec Passes!
describe ‘what the regex matches’
# FOR REFERENCE: /:([[:alnum:]]+)[[:space:]]=>/
let(:string) {‘:ab'}
it 'matches a string' do
expect(do_system_things.first_regex_match(string))
.not_to be_nil
end
end
111. First Do No Harm: Surgical Refactoring @nellshamrell
spec/do_system_things_spec.rb
But…we were expecting a failure…
describe ‘what the regex matches’
# FOR REFERENCE: /:([[:alnum:]]+)[[:space:]]=>/
let(:string) {‘:ab'}
it 'matches a string' do
expect(do_system_things.first_regex_match(string))
.not_to be_nil
end
end
112. First Do No Harm: Surgical Refactoring @nellshamrell
lib/do_system_things.rb
class DoSystemThings
def first_regex_match(string)
/:[[:alnum:]]/.match(string)
end
def do_the_thing(dir)
system "sed -E -i '' 's/:([[:alnum:]]+)[[:space:]]=>/1:/g'
#{dir}/**/*.rb"
end
end Will return successful match with
only one alnum character
113. First Do No Harm: Surgical Refactoring @nellshamrell
spec/do_system_things_spec.rb
describe ‘what the regex matches’
# FOR REFERENCE: /:([[:alnum:]]+)[[:space:]]=>/
let(:string) {‘:ab'}
it 'matches a string' do
expect(do_system_things.first_regex_match(string)
.to_s).to include(‘:ab’)
end
end
Examining content of string that was
captured by the regex
114. First Do No Harm: Surgical Refactoring @nellshamrell
spec/do_system_things_spec.rb
Spec Fails!
describe ‘what the regex matches’
# FOR REFERENCE: /:([[:alnum:]]+)[[:space:]]=>/
let(:string) {‘:ab'}
it 'matches a string' do
expect(do_system_things.first_regex_match(string)
.to_s).to include(‘:ab’)
end
end
115. First Do No Harm: Surgical Refactoring @nellshamrell
lib/do_system_things.rb
class DoSystemThings
def first_regex_match(string)
/:[[:alnum:]]+/.match(string)
end
def do_the_thing(dir)
system "sed -E -i '' 's/:([[:alnum:]]+)[[:space:]]=>/1:/g'
#{dir}/**/*.rb"
end
end
add + quantifier
116. First Do No Harm: Surgical Refactoring @nellshamrell
lib/do_system_things.rb
class DoSystemThings
def first_regex_match(string)
/:[[:alnum:]]+/.match(string)
end
def do_the_thing(dir)
system "sed -E -i '' 's/:([[:alnum:]]+)[[:space:]]=>/1:/g'
#{dir}/**/*.rb"
end
end
Spec Passes!
117. First Do No Harm: Surgical Refactoring @nellshamrell
spec/do_system_things_spec.rb
# FOR REFERENCE: /:([[:alnum:]]+)[[:space:]]=>/
let(:string) {‘:ab'}
it 'matches a string' do
expect(do_system_things.first_regex_match(string)
.to_s).to include(‘:ab’)
end
Capture group
118. First Do No Harm: Surgical Refactoring @nellshamrell
spec/do_system_things_spec.rb
# FOR REFERENCE: /:([[:alnum:]]+)[[:space:]]=>/
let(:string) {‘:ab'}
it 'matches a string' do
expect(do_system_things.first_regex_match(string)
.to_s).to include(‘:ab’)
end
it ‘captures a group’ do
end
119. First Do No Harm: Surgical Refactoring @nellshamrell
spec/do_system_things_spec.rb
# FOR REFERENCE: /:([[:alnum:]]+)[[:space:]]=>/
let(:string) {‘:ab'}
it 'matches a string' do
expect(do_system_things.first_regex_match(string)
.to_s).to include(‘:ab’)
end
it ‘captures a group’ do
expect(do_system_things.first_regex_match(string)[1])
.not_to be_nil
end Testing that match captures
a capture group ([1] references
first capture group)
120. First Do No Harm: Surgical Refactoring @nellshamrell
spec/do_system_things_spec.rb
Spec Fails!
# FOR REFERENCE: /:([[:alnum:]]+)[[:space:]]=>/
let(:string) {‘:ab'}
it 'matches a string' do
expect(do_system_things.first_regex_match(string)
.to_s).to include(‘:ab’)
end
it ‘captures a group’ do
expect(do_system_things.first_regex_match(string)[1])
.not_to be_nil
end
121. First Do No Harm: Surgical Refactoring @nellshamrell
lib/do_system_things.rb
class DoSystemThings
def first_regex_match(string)
/:[[:alnum:]]+()/.match(string)
end
def do_the_thing(dir)
system "sed -E -i '' 's/:([[:alnum:]]+)[[:space:]]=>/1:/g'
#{dir}/**/*.rb"
end
end
Adding empty capture group
122. First Do No Harm: Surgical Refactoring @nellshamrell
lib/do_system_things.rb
class DoSystemThings
def first_regex_match(string)
/:[[:alnum:]]+()/.match(string)
end
def do_the_thing(dir)
system "sed -E -i '' 's/:([[:alnum:]]+)[[:space:]]=>/1:/g'
#{dir}/**/*.rb"
end
end
Spec Passes!
123. First Do No Harm: Surgical Refactoring @nellshamrell
spec/do_system_things_spec.rb
# FOR REFERENCE: /:([[:alnum:]]+)[[:space:]]=>/
let(:string) {‘:ab'}
it 'matches a string' do
expect(do_system_things.first_regex_match(string)
.to_s).to include(‘:ab’)
end
it ‘captures a group’ do
expect(do_system_things.first_regex_match(string)[1])
.not_to be_nil
expect(do_system_things.first_regex_match(string)[1])
.to eq(‘ab’)
end
Testing content of capture group
124. First Do No Harm: Surgical Refactoring @nellshamrell
spec/do_system_things_spec.rb
Spec Fails!
# FOR REFERENCE: /:([[:alnum:]]+)[[:space:]]=>/
let(:string) {‘:ab'}
it 'matches a string' do
expect(do_system_things.first_regex_match(string)
.to_s).to include(‘:ab’)
end
it ‘captures a group’ do
expect(do_system_things.first_regex_match(string)[1])
.not_to be_nil
expect(do_system_things.first_regex_match(string)[1])
.to eq(‘ab’)
end
125. First Do No Harm: Surgical Refactoring @nellshamrell
lib/do_system_things.rb
class DoSystemThings
def first_regex_match(string)
/:([[:alnum:]]+)/.match(string)
end
def do_the_thing(dir)
system "sed -E -i '' 's/:([[:alnum:]]+)[[:space:]]=>/1:/g'
#{dir}/**/*.rb"
end
end
Placing capture group in
correct place
126. First Do No Harm: Surgical Refactoring @nellshamrell
lib/do_system_things.rb
class DoSystemThings
def first_regex_match(string)
/:([[:alnum:]]+)/.match(string)
end
def do_the_thing(dir)
system "sed -E -i '' 's/:([[:alnum:]]+)[[:space:]]=>/1:/g'
#{dir}/**/*.rb"
end
end
Spec Passes!
127. First Do No Harm: Surgical Refactoring @nellshamrell
lib/do_system_things.rb
class DoSystemThings
def first_regex_match(string)
/:([[:alnum:]]+)[[:space]]=>/.match(string)
end
def do_the_thing(dir)
system "sed -E -i '' 's/:([[:alnum:]]+)[[:space:]]=>/1:/g'
#{dir}/**/*.rb"
end
end
Fast Forward…
(Adding in tests for rest of characters)
128. First Do No Harm: Surgical Refactoring @nellshamrell
lib/do_system_things.rb
class DoSystemThings
def first_regex_match(string)
/:([[:alnum:]]+)[[:space]]=>/.match(string)
end
def do_the_thing(dir)
system "sed -E -i '' 's/:([[:alnum:]]+)[[:space:]]=>/1:/g'
#{dir}/**/*.rb"
end
end We know what this regex does!
‘:ab =>’ matches!
129. First Do No Harm: Surgical Refactoring @nellshamrell
spec/do_system_things_spec.rb
context ‘changing the file’ do
before do
file = File.open(File.join(directory_path,file_name))
file.write(':ab =>')
file.close
end
end
Write sample string to file
(note the space and hash rocket)
130. First Do No Harm: Surgical Refactoring @nellshamrell
spec/do_system_things_spec.rb
context ‘changing the file’ do
it ‘changes the file’ do
original_contents =
File.read(File.join(directory_path,file_name))
end
end
Capture original contents of file
131. First Do No Harm: Surgical Refactoring @nellshamrell
spec/do_system_things_spec.rb
context ‘changing the file’ do
it ‘changes the file’ do
original_contents =
File.read(File.join(directory_path,file_name))
do_system_things.do_the_thing(directory_name)
end
end
Call the method
132. First Do No Harm: Surgical Refactoring @nellshamrell
spec/do_system_things_spec.rb
context ‘changing the file’ do
it ‘changes the file’ do
original_contents =
File.read(File.join(directory_path,file_name))
do_system_things.do_the_thing(directory_name)
new_contents = File.read
(File.join(directory_path,file_name))
end
end
Capture new contents of file
133. First Do No Harm: Surgical Refactoring @nellshamrell
spec/do_system_things_spec.rb
context ‘changing the file’ do
it ‘changes the file’ do
original_contents =
File.read(File.join(directory_path,file_name))
do_system_things.do_the_thing(directory_name)
new_contents = File.read
(File.join(directory_path,file_name))
expect(original_contents).not_to eq(new_contents)
end
end
Make sure file changes
134. First Do No Harm: Surgical Refactoring @nellshamrell
spec/do_system_things_spec.rb
context ‘changing the file’ do
it ‘changes the file’ do
original_contents =
File.read(File.join(directory_path,file_name))
do_system_things.do_the_thing(directory_name)
new_contents = File.read
(File.join(directory_path,file_name))
expect(original_contents).not_to eq(new_contents)
end
end
Spec Passes!
135. First Do No Harm: Surgical Refactoring @nellshamrell
lib/do_system_things.rb
class DoSystemThings
def do_the_thing(dir)
system "sed -E -i '' 's/:([[:alnum:]]+)[[:space:]]=>/1:/g'
#{dir}/**/*.rb"
end
end
*pause*
136. First Do No Harm: Surgical Refactoring @nellshamrell
lib/do_system_things.rb
Replace match for the
first pattern with this
second pattern
s/:([[:alnum:]]+)[[:space:]]=>/1:/g'
137. First Do No Harm: Surgical Refactoring @nellshamrell
lib/do_system_things.rb
1:
138. First Do No Harm: Surgical Refactoring @nellshamrell
lib/do_system_things.rb
1:
Escape - so we can use a literal
as the next character
139. First Do No Harm: Surgical Refactoring @nellshamrell
lib/do_system_things.rb
1:
Uses the result of the first capture group
from the first pattern
140. First Do No Harm: Surgical Refactoring @nellshamrell
lib/do_system_things.rb
1:
Adds a literal colon
141. First Do No Harm: Surgical Refactoring @nellshamrell
lib/do_system_things.rb
s/:([[:alnum:]]+)[[:space:]]=>/1:/g'
‘:ab =>’
142. First Do No Harm: Surgical Refactoring @nellshamrell
lib/do_system_things.rb
s/:([[:alnum:]]+)[[:space:]]=>/1:/g'
‘ab:’‘:ab =>’ replace with
143. First Do No Harm: Surgical Refactoring @nellshamrell
spec/do_system_things_spec.rb
context ‘changing the file’ do
let(:orig_string) { “:ab => “}
let(:new_string) { “ab: ‘}
it ‘changes the file’ do
original_contents = File.read(File.join(directory_path,file_name))
do_system_things.do_the_thing(directory_name)
new_contents = File.read(File.join(directory_path,file_name))
end
end
Expected content of file
before and after
144. First Do No Harm: Surgical Refactoring @nellshamrell
spec/do_system_things_spec.rb
context ‘changing the file’ do
let(:orig_string) { “:ab => “}
let(:new_string) { “ab: ‘}
it ‘changes the file’ do
original_contents = File.read(File.join(directory_path,file_name))
do_system_things.do_the_thing(directory_name)
new_contents = File.read(File.join(directory_path,file_name))
expect(new_contents).not_to include(orig_string)
expect(new_contents).to include(new_string)
end
end
Verify contents of
modified file
145. First Do No Harm: Surgical Refactoring @nellshamrell
spec/do_system_things_spec.rb
context ‘changing the file’ do
let(:orig_string) { “:ab => “}
let(:new_string) { “ab: ‘}
it ‘changes the file’ do
original_contents = File.read(File.join(directory_path,file_name))
do_system_things.do_the_thing(directory_name)
new_contents = File.read(File.join(directory_path,file_name))
expect(new_contents).not_to include(orig_string)
expect(new_contents).to include(new_string)
end
end
Spec Passes!
146. First Do No Harm: Surgical Refactoring @nellshamrell
lib/do_system_things.rb
class DoSystemThings
def do_the_thing(dir)
system "sed -E -i '' 's/:([[:alnum:]]+)[[:space:]]=>/1:/g'
#{dir}/**/*.rb"
end
end
*pause*
147. First Do No Harm: Surgical Refactoring @nellshamrell
lib/do_system_things.rb
s/:([[:alnum:]]+)[[:space:]]=>/1:/g'
Replace all matches for the
first pattern with the second
pattern
148. First Do No Harm: Surgical Refactoring @nellshamrell
spec/do_system_things_spec.rb
context ‘changing the file’ do
let(:orig_string) { “:ab => :ab =>“}
let(:new_string) { “ab: ab:’}
it ‘changes all matches within the file’ do
original_contents = File.read(File.join(directory_path,file_name))
do_system_things.do_the_thing(directory_name)
new_contents = File.read(File.join(directory_path,file_name))
expect(new_contents).not_to include(orig_string)
expect(new_contents).to include(new_string)
end
end
Expected content of
file before and after
149. First Do No Harm: Surgical Refactoring @nellshamrell
spec/do_system_things_spec.rb
context ‘changing the file’ do
let(:orig_string) { “:ab => :ab =>“}
let(:new_string) { “ab: ab:’}
it ‘changes all matches within the file’ do
original_contents = File.read(File.join(directory_path,file_name))
do_system_things(directory_name)
new_contents = File.read(File.join(directory_path,file_name))
expect(new_contents).not_to include(orig_string)
expect(new_contents).to include(new_string)
end
end Spec Passes!
150. First Do No Harm: Surgical Refactoring @nellshamrell
lib/do_system_things.rb
class DoSystemThings
def do_the_thing(dir)
system "sed -E -i '' ’s/:([[:alnum:]]+)[[:space:]]=>/1:/"
#{dir}/**/*.rb"
end
end
Taking out the
global flag
151. First Do No Harm: Surgical Refactoring @nellshamrell
lib/do_system_things.rb
class DoSystemThings
def do_the_thing(dir)
system "sed -E -i '' ’s/:([[:alnum:]]+)[[:space:]]=>/1:/"
#{dir}/**/*.rb"
end
end
Spec Fails!
152. First Do No Harm: Surgical Refactoring @nellshamrell
lib/do_system_things.rb
class DoSystemThings
def do_the_thing(dir)
system "sed -E -i '' ’s/:([[:alnum:]]+)[[:space:]]=>/1:/g"
#{dir}/**/*.rb"
end
end
Putting the flag
back in
153. First Do No Harm: Surgical Refactoring @nellshamrell
lib/do_system_things.rb
class DoSystemThings
def do_the_thing(dir)
system "sed -E -i '' ’s/:([[:alnum:]]+)[[:space:]]=>/1:/g"
#{dir}/**/*.rb"
end
end
Spec Passes!
154. First Do No Harm: Surgical Refactoring @nellshamrell
lib/do_system_things.rb
class DoSystemThings
def do_the_thing(dir)
system "sed -E -i '' ’s/:([[:alnum:]]+)[[:space:]]=>/1:/g"
#{dir}/**/*.rb"
end
end
Next step…add in tests for these flags
155. First Do No Harm: Surgical Refactoring @nellshamrell
lib/do_system_things.rb
class DoSystemThings
def do_the_thing(dir)
# taking the -E flag out
system "sed -i '' ’s/:([[:alnum:]]+)[[:space:]]=>/1:/g"
#{dir}/**/*.rb"
end
end
156. First Do No Harm: Surgical Refactoring @nellshamrell
lib/do_system_things.rb
class DoSystemThings
def do_the_thing(dir)
# taking the -E flag out
system "sed -i '' ’s/:([[:alnum:]]+)[[:space:]]=>/1:/g"
#{dir}/**/*.rb"
end
end
Spec Fails!
157. First Do No Harm: Surgical Refactoring @nellshamrell
lib/do_system_things.rb
class DoSystemThings
def do_the_thing(dir)
# putting the -E flag back in
system "sed E —i '' ’s/:([[:alnum:]]+)[[:space:]]=>/1:/g"
#{dir}/**/*.rb"
end
end
158. First Do No Harm: Surgical Refactoring @nellshamrell
lib/do_system_things.rb
class DoSystemThings
def do_the_thing(dir)
# putting the -E flag back in
system "sed E —i '' ’s/:([[:alnum:]]+)[[:space:]]=>/1:/g"
#{dir}/**/*.rb"
end
end
159. First Do No Harm: Surgical Refactoring @nellshamrell
lib/do_system_things.rb
class DoSystemThings
def do_the_thing(dir)
# putting the -E flag back in
system "sed E —i '' ’s/:([[:alnum:]]+)[[:space:]]=>/1:/g"
#{dir}/**/*.rb"
end
end
Spec Passes!
160. First Do No Harm: Surgical Refactoring @nellshamrell
lib/do_system_things.rb
class DoSystemThings
def do_the_thing(dir)
system "sed E —i '' ’s/:([[:alnum:]]+)[[:space:]]=>/1:/g"
#{dir}/**/*.rb"
end
end
161. First Do No Harm: Surgical Refactoring @nellshamrell
spec/do_system_things_spec.rb
context ‘changing the file’ do
it ‘does not save a backup copy of the file’ do
# Expect the subdirectory we created to contain only one file
expect(Dir[“#{directory_name}/#{subdirectory_name}/*”]
.count).to eq(1)
end
end
162. First Do No Harm: Surgical Refactoring @nellshamrell
spec/do_system_things_spec.rb
context ‘changing the file’ do
it ‘does not save a backup copy of the file’ do
# Expect the subdirectory we created to contain only one file
expect(Dir[“#{directory_name}/#{subdirectory_name}/*”]
.count).to eq(1)
do_system_things.do_the_thing(directory_name)
end
end
163. First Do No Harm: Surgical Refactoring @nellshamrell
spec/do_system_things_spec.rb
context ‘changing the file’ do
it ‘does not save a backup copy of the file’ do
# Expect the subdirectory we created to contain only one file
expect(Dir[“#{directory_name}/#{subdirectory_name}/*”]
.count).to eq(1)
do_system_things.do_the_thing(directory_name)
expect(Dir[“#{directory_name}/#{subdirectory_name}/*”]
.count).to eq(1)
end
end
164. First Do No Harm: Surgical Refactoring @nellshamrell
spec/do_system_things_spec.rb
context ‘changing the file’ do
it ‘does not save a backup copy of the file’ do
# Expect the subdirectory we created to contain only one file
expect(Dir[“#{directory_name}/#{subdirectory_name}/*”]
.count).to eq(1)
do_system_things.do_the_thing(directory_name)
expect(Dir[“#{directory_name}/#{subdirectory_name}/*”]
.count).to eq(1)
end
end
Spec Passes!
165. First Do No Harm: Surgical Refactoring @nellshamrell
lib/do_system_things.rb
class DoSystemThings
def do_the_thing(dir)
# adding an extension to the -i flag
system "sed E —i .tmp ’s/:([[:alnum:]]+)[[:space:]]=>/1:/g"
#{dir}/**/*.rb"
end
end
166. First Do No Harm: Surgical Refactoring @nellshamrell
lib/do_system_things.rb
class DoSystemThings
def do_the_thing(dir)
# adding an extension to the -i flag
system "sed E —i .tmp ’s/:([[:alnum:]]+)[[:space:]]=>/1:/g"
#{dir}/**/*.rb”
end
end
Spec Fails!
167. First Do No Harm: Surgical Refactoring @nellshamrell
lib/do_system_things.rb
class DoSystemThings
def do_the_thing(dir)
# removing extension to -i flag
system "sed E —i ‘’ ’s/:([[:alnum:]]+)[[:space:]]=>/1:/g"
#{dir}/**/*.rb"
end
end
168. First Do No Harm: Surgical Refactoring @nellshamrell
lib/do_system_things.rb
class DoSystemThings
def do_the_thing(dir)
# removing extension to -i flag
system "sed E —i ‘’ ’s/:([[:alnum:]]+)[[:space:]]=>/1:/g"
#{dir}/**/*.rb"
end
end
Spec Passes!
169. First Do No Harm: Surgical Refactoring @nellshamrell
lib/do_system_things.rb
class DoSystemThings
def do_the_thing(dir)
system "sed -E -i '' ’s/:([[:alnum:]]+)[[:space:]]=>/1:/g"
#{dir}/**/*.rb"
end
end
We know what this does!
171. First Do No Harm: Surgical Refactoring @nellshamrell
lib/do_system_things.rb
class DoSystemThings
def do_the_thing(dir)
system "sed -E -i '' 's/:([[:alnum:]]+)[[:space:]]=>/1:/g'
#{dir}/**/*.rb"
end
end
172. First Do No Harm: Surgical Refactoring @nellshamrell
lib/do_system_things.rb
class DoSystemThings
def do_the_thing(dir)
system "sed -E -i '' 's/:([[:alnum:]]+)[[:space:]]=>/1:/g'
#{dir}/**/*.rb"
end
end
173. First Do No Harm: Surgical Refactoring @nellshamrell
lib/do_system_things.rb
class DoSystemThings
def do_the_thing(dir)
system "sed -E -i '' 's/:([[:alnum:]]+)[[:space:]]=>/1:/g'
#{dir}/**/*.rb"
end
private
def substitute_command
's/:([[:alnum:]]+)[[:space:]]=>/1:/g'
end
end
174. First Do No Harm: Surgical Refactoring @nellshamrell
lib/do_system_things.rb
class DoSystemThings
def do_the_thing(dir)
system "sed -E -i '' #{substitute_command} #{dir}/**/*.rb"
end
private
def substitute_command
's/:([[:alnum:]]+)[[:space:]]=>/1:/g'
end
end
175. First Do No Harm: Surgical Refactoring @nellshamrell
lib/do_system_things.rb
class DoSystemThings
def do_the_thing(dir)
system "sed -E -i '' #{substitute_command} #{dir}/**/*.rb"
end
private
def substitute_command
's/:([[:alnum:]]+)[[:space:]]=>/1:/g'
end
end
Specs Pass!
176. First Do No Harm: Surgical Refactoring @nellshamrell
lib/do_system_things.rb
class DoSystemThings
def do_the_thing(dir)
system "sed -E -i '' #{substitute_command} #{dir}/**/*.rb"
end
private
def substitute_command
's/:([[:alnum:]]+)[[:space:]]=>/1:/g'
end
end Really old regex syntax
177. First Do No Harm: Surgical Refactoring @nellshamrell
lib/do_system_things.rb
class DoSystemThings
def do_the_thing(dir)
system "sed -E -i '' #{substitute_command} #{dir}/**/*.rb"
end
private
def substitute_command
’s/:(w+)s=>/1:/g’
end
end New regex syntax
178. First Do No Harm: Surgical Refactoring @nellshamrell
lib/do_system_things.rb
class DoSystemThings
def do_the_thing(dir)
system "sed -E -i '' #{substitute_command} #{dir}/**/*.rb"
end
private
def substitute_command
’s/:(w+)s=>/1:/g’
end
end Specs Fail!
w != [:alnum]
179. First Do No Harm: Surgical Refactoring @nellshamrell
lib/do_system_things.rb
class DoSystemThings
def do_the_thing(dir)
system "sed -E -i '' #{substitute_command} #{dir}/**/*.rb"
end
private
def substitute_command
's/:([[:alnum:]]+)[[:space:]]=>/1:/g'
end
end Back to the old
regex syntax
180. First Do No Harm: Surgical Refactoring @nellshamrell
lib/do_system_things.rb
class DoSystemThings
def do_the_thing(dir)
system "sed -E -i '' #{substitute_command} #{dir}/**/*.rb"
end
private
def substitute_command
's/:([[:alnum:]]+)[[:space:]]=>/1:/g'
end
end
Specs Pass!
182. What do I need to do after refactoring?
First Do No Harm: Surgical Refactoring @nellshamrell
Need to know two things decisively
183. What do I need to do after refactoring?
First Do No Harm: Surgical Refactoring @nellshamrell
Need to know two things decisively
1) Does the behavior still exist?
184. What do I need to do after refactoring?
First Do No Harm: Surgical Refactoring @nellshamrell
Need to know two things decisively
1) Does the behavior still exist?
2) Is it connected correctly?
185. What do I need to do after refactoring?
First Do No Harm: Surgical Refactoring @nellshamrell
What about QA?
186. What do I need to do after refactoring?
First Do No Harm: Surgical Refactoring @nellshamrell
Ideally, QA should find nothing
187. What if something goes wrong?
First Do No Harm: Surgical Refactoring @nellshamrell
188. What if something goes wrong?
First Do No Harm: Surgical Refactoring @nellshamrell
1) Take responsibility - what your code does
in production is your responsibility
189. What if something goes wrong?
First Do No Harm: Surgical Refactoring @nellshamrell
1) Take responsibility - what your code does
in production is your responsibility
2) Evaluate risk of another change
(a change to a change is still a change)
190. What if something goes wrong?
First Do No Harm: Surgical Refactoring @nellshamrell
1) Take responsibility - what your code does
in production is your responsibility
2) Evaluate risk of another change
(a change to a change is still a change)
3) Fix the problem (if you can’t, find someone
who can!)
191. Conclusion
First Do No Harm: Surgical Refactoring @nellshamrell
“I’m not a great programmer, I’m just a good
programmer with great habits”
- “Refactoring: Ruby Edition”
192. Thank You!
First Do No Harm: Surgical Refactoring @nellshamrell
Nell Shamrell-Harrington
Software Development Engineer at Chef
@nellshamrell
www.nellshamrell.com
nshamrell@chef.io