A very short presentation for demonstrating ABC Size, a software code complexity measure.

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ABC Size
Dave Doolin
A code complexity metric, easy as 1-2-3.
April 21, 2024
ABC Sise

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ABC Size
Assignment, Branch, Condition
Definition of ABC Size:
√
A2 +B2 +C2
A: Assignment
B: Branch (method calls)
C: Conditional
ABC Sise

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Rubocop
ftw
For demonstration purposes, we’ll set Metrics/AbcSize to 0.
1 # Just enough rubocop for demonstration
2
3 AllCops:
4 NewCops: enable
5
6 Style/FrozenStringLiteralComment:
7 Enabled: false
8
9 # Set to 0 to force output
10 Metrics/AbcSize:
11 Max: 0
ABC Sise

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Example
Let’s count!
1 # Demonstration of ABC Size
2 class AbcSize
3 def demonstrate
4 a = 'foo'
5 b = 'bar'
6 c = rand(2).even? ? 'baz' : 'quux'
7 a + b + c # a.+ b.+ c
8 end
9 end
ABC Sise

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Example
Let’s count!
1 # Demonstration of ABC Size
2 class AbcSize
3 def demonstrate
4 a = 'foo'
5 b = 'bar'
6 c = rand(2).even? ? 'baz' : 'quux'
7 a + b + c # a.+ b.+ c
8 end
9 end
Assignments:
ABC Sise

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Example
Let’s count!
1 # Demonstration of ABC Size
2 class AbcSize
3 def demonstrate
4 a = 'foo'
5 b = 'bar'
6 c = rand(2).even? ? 'baz' : 'quux'
7 a + b + c # a.+ b.+ c
8 end
9 end
Assignments: 3
ABC Sise

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Example
Let’s count!
1 # Demonstration of ABC Size
2 class AbcSize
3 def demonstrate
4 a = 'foo'
5 b = 'bar'
6 c = rand(2).even? ? 'baz' : 'quux'
7 a + b + c # a.+ b.+ c
8 end
9 end
Assignments: 3
Branches:
ABC Sise

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Example
Let’s count!
1 # Demonstration of ABC Size
2 class AbcSize
3 def demonstrate
4 a = 'foo'
5 b = 'bar'
6 c = rand(2).even? ? 'baz' : 'quux'
7 a + b + c # a.+ b.+ c
8 end
9 end
Assignments: 3
Branches: 4
ABC Sise

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Example
Let’s count!
1 # Demonstration of ABC Size
2 class AbcSize
3 def demonstrate
4 a = 'foo'
5 b = 'bar'
6 c = rand(2).even? ? 'baz' : 'quux'
7 a + b + c # a.+ b.+ c
8 end
9 end
Assignments: 3
Branches: 4
Conditionals:
ABC Sise

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Example
Let’s count!
1 # Demonstration of ABC Size
2 class AbcSize
3 def demonstrate
4 a = 'foo'
5 b = 'bar'
6 c = rand(2).even? ? 'baz' : 'quux'
7 a + b + c # a.+ b.+ c
8 end
9 end
Assignments: 3
Branches: 4
Conditionals: 1
ABC Sise

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Example
Let’s count!
1 # Demonstration of ABC Size
2 class AbcSize
3 def demonstrate
4 a = 'foo'
5 b = 'bar'
6 c = rand(2).even? ? 'baz' : 'quux'
7 a + b + c # a.+ b.+ c
8 end
9 end
Assignments: 3
Branches: 4
Conditionals: 1
AbcSize:
ABC Sise

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Example
Let’s count!
1 # Demonstration of ABC Size
2 class AbcSize
3 def demonstrate
4 a = 'foo'
5 b = 'bar'
6 c = rand(2).even? ? 'baz' : 'quux'
7 a + b + c # a.+ b.+ c
8 end
9 end
Assignments: 3
Branches: 4
Conditionals: 1
AbcSize:
√
26 ≈ 5.1
ABC Sise

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What does Rubocop say?
code/abc_size.rb
: 6 : 3 : C: Metrics/AbcSize :
Assignment Branch Condition s i z e f o r demonstrate
i s too high . [<3, 4 , 1> 5.1/0]
ABC Sise

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Reducing ABC Size
For Ruby, use Rubocop
The main way to reduce ABC size is refactoring. It’s that simple.
ABC Sise

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Reducing ABC Size
For Ruby, use Rubocop
The main way to reduce ABC size is refactoring. It’s that simple.
Well-factored programs tend to have lower ABC Size.
ABC Sise

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.
.
.
Reducing ABC Size
For Ruby, use Rubocop
The main way to reduce ABC size is refactoring. It’s that simple.
Well-factored programs tend to have lower ABC Size.
It’s really that simple.
ABC Sise

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One major caveat...
...you have to do the work
THE MOST IMPORTANT PART IS TO ENABLE THE METRIC!
ABC Sise

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One major caveat...
...you have to do the work
THE MOST IMPORTANT PART IS TO ENABLE THE METRIC!
1 Metrics/AbcSize:
2 Enabled: true
3 Max: 15 # Rubocop default
ABC Sise

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Other complexity measures
Same code, different information
Others for later:
• Cyclomatic (McCabe) Complexity
• Perceived Complexity
• LCOM (Lack of Cohesion of Methods)
ABC Sise

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Have fun!
and remember
ABC is a simple metric, it’s not a silver bullet. Not every method is
amenable to low ABC size. It’s a tool, and very good tool at that.
ABC Sise

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References
• ABC Software Metric
• Rubocop default.yml
• C2 Wiki: AbcMetric
ABC Sise

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Questions?
ABC Sise