1.
Can We Automatically Generate Class
Comments in Pharo?
Pooja Rani, Alexandre Bergel,
Lino Hess, Timo Kehrer, Oscar Nierstrasz
University of Bern, Switzerland
International Workshop on Smalltalk Technologies,
Novi Sad, Serbia, 2022

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High-quality code comments assist developers

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Developers find writing comments a boring and effort-intensive task

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To support developers in writing comments,
communities suggest coding guidelines
Apache
Oracle
Google Pharo
PEP8/257

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To support developers in writing comments,
communities suggest coding guidelines
Apache
Oracle
Google Pharo
PEP8/257

7.
7
To support developers in writing comments,
communities suggest coding guidelines
Apache
Oracle
Google Pharo
PEP8/257

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8
To support developers in writing comments,
communities suggest coding guidelines
Apache
Oracle
Google Pharo
PEP8/257

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9
- Rani et al., Empirical Software Engineering, 2021
Developers follow template inspired information types more often
To support developers in writing comments,
communities suggest coding guidelines
Apache
Oracle
Google Pharo
PEP8/257

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Color scale according to number of comments falling into a category
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Categories
Pharo
versions
(total
classes)
Developers follow template inspired information types more often
- Rani et al., Empirical Software Engineering, 2021

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Can we automatically generate these information types?
Color scale according to number of comments falling into a category
0 25 52
0 26 52
1 (52)
2 (52)
3 (52)
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6 (52)
7 (52)
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Categories
Pharo
versions
(total
classes)

12.
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Objects are responsible members of an
object community
Rebecca Wirfs-Brock
Object role stereotypes in 1992 in a Smalltalk Report article

13.
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Objects are responsible members of an
object community
Rebecca Wirfs-Brock
Object role stereotypes in 1992 in a Smalltalk Report article

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Controller
Coordinator
Structure
Interface
Information holder
Objects are responsible members of an
object community
Rebecca Wirfs-Brock
Object role stereotypes in 1992 in a Smalltalk Report article

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Controller
Coordinator
Structure
Interface
Information holder
Objects are responsible members of an
object community
Object role stereotypes in 1992 in a Smalltalk Report article
Stereotype-based approach

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Previous works

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Previous works

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Previous works

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Previous works

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Methodology Dataset
Can We Automatically Generate Class Comments in
Pharo?
Previous works

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Methodology
Identify
class stereotype
Identify method
stereotypes
Pharo 8 Extract
method information
Extract
class
information
Fill
template
1 2 3 4 5

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• Accessor
• Getter
• Mutator
• Setter
• Creational
• Collaborator
• Degnerate
• Controller
Method Stereotypes
1

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4%
4%
4%
5%
10%
16%
28%
33%
Set
Get
Controller
Creational
Mutator
Degenerate
Collaborator
Accessor
Distribution of Stereotypes
• Accessor
• Getter
• Mutator
• Setter
• Creational
• Collaborator
• Degnerate
• Controller
Method Stereotypes
1

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• Entity
• Minimal Entity
• Data Provider
• Commander
• Boundary
• Factory
• Empty
• Small
• Controller
• Pure Controller
• Large
• Lazy
• Degenerate
• Data
Class Stereotypes
2
4%
4%
4%
5%
10%
16%
28%
33%
Set
Get
Controller
Creational
Mutator
Degenerate
Collaborator
Accessor
• Accessor
• Getter
• Mutator
• Setter
• Creational
• Collaborator
• Degnerate
• Controller
Method Stereotypes
1
Distribution of Stereotypes

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0%
1%
2%
2%
2%
2%
2%
3%
5%
6%
7%
9%
23%
42%
PureController
Lazy
Controller
Data
Entity
Factory
MinimalEntity
Empty
Commander
Small
Large
Degenerate
Boundary
DataProvider
4%
4%
4%
5%
10%
16%
28%
33%
Set
Get
Controller
Creational
Mutator
Degenerate
Collaborator
Accessor
• Entity
• Minimal Entity
• Data Provider
• Commander
• Boundary
• Factory
• Empty
• Small
• Controller
• Pure Controller
• Large
• Lazy
• Degenerate
• Data
Class Stereotypes
2
• Accessor
• Getter
• Mutator
• Setter
• Creational
• Collaborator
• Degnerate
• Controller
Method Stereotypes
1
Distribution of Stereotypes

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• Entity
• Minimal Entity
• Data Provider
• Commander
• Boundary
• Factory
• Empty
• Small
• Controller
• Pure Controller
• Large
• Lazy
• Degenerate
• Data
Class Stereotypes
2
• Accessor
• Getter
• Mutator
• Setter
• Creational
• Collaborator
• Degnerate
• Controller
Method Stereotypes
1

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Small
Controller
Pure Controller
Large
Lazy
Degenerate
Data
otypes
reational
ollaborator
egnerate
ontroller
eotypes

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• External used methods
• Internally used methods
Method Information
3
• Class name
• Class stereotype description
• Classes used by the class
• Dependent classes
• Relevant keywords
Class Information
4
Small
Controller
Pure Controller
Large
Lazy
Degenerate
Data
otypes
reational
ollaborator
egnerate
ontroller
eotypes

29.
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• External used methods
• Internally used methods
Method Information
3
• Class name
• Class stereotype description
• Classes used by the class
• Dependent classes
• Relevant keywords
Class Information
4
Small
Controller
Pure Controller
Large
Lazy
Degenerate
Data
otypes
reational
ollaborator
egnerate
ontroller
eotypes

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30
• External used methods
• Internally used methods
Method Information
3
• Class name
• Class stereotype description
• Classes used by the class
• Dependent classes
• Relevant keywords
Class Information
4
Small
Controller
Pure Controller
Large
Lazy
Degenerate
Data
otypes
reational
ollaborator
egnerate
ontroller
eotypes

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24 class comments (auto generated)
3 developers: each comment evaluated by three
42 evaluations: 7 developers completed it
3 metrics: Adequacy, Conciseness, Comprehensibility
Evaluation

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Evaluation
Adequacy: 44% participants said the comment is missing some important information

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Conciseness- 54% participants said the comment contains a lot of
unnecessary information
Evaluation
Adequacy: 44% participants said the comment is missing some important information