Using Structural Context to Recommend Source Code Examples

1
Using Structural Context to Recommend Source
Code Examples

• Reid Holmes and Gail C. Murphy

2
The Problem A Concrete Example

• Frameworks can improve developer productivity.
  But developers can become stuck trying to use the
  APIs
• Imagine trying to use the Eclipse APIs to place
  text in the status line of the Eclipse IDE
• Eclipse has 38,000 public methods

3
The Problem A Concrete Example
Search the documentation status line eclipse
4
The Problem A Concrete Example

• An expert might reveal
• How can we deliver this kind of example to a
  developer?

5
Previous Approaches

• Past approaches have tried to deliver examples
• Reuse View Matcher Rosson Carroll 91
• Provide constructed examples to developers
• Framework developer must explicitly create
  examples
• CodeFinder Henninger 91
• Help developers construct effective queries
• Developer needs to construct query manually
• CodeBroker Ye Fischer 01,02
• Locate similar code using comments and method
  signatures
• Intent is to locate similar code, not usage

6
Our Approach An Overview
Development Environment
7
Strathcona User Perspective
Write Code Fragment
Extract Structural Context
Browse Examples
Integrate Relevant Code
User Actions
Strathcona Actions
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Strathcona Extract Structural Context
ViewPart
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Strathcona Example Navigation

• Visual representation
• Highlights key relationships between example and
  query
• Multiple examples can be quickly viewed

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Strathcona Viewing Example Source

• Code view
• Example shows how to get a status line manager
• Example is not a perfect match, but good enough
  to help

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Strathcona Server Side

• Repository consists of existing projects
• Structural context is automatically extracted
• Examples are not pre-computed
• Relevant source is located by heuristics
• Example is built from relevant code
• Eclipse example repository consists of source for
  release 3.0
• 17,456 classes
• 124,359 methods
• 1,066,838 calls
• 15,187 inheritance links

Write Code Fragment
Existing Projects
Project Repository
Strathcona Server
Browse Examples
Integrate Relevant Code
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Strathcona Heuristics

• Six heuristics locate structurally relevant
  examples
• Inheritance
• Calls
• Calls with inheritance
• Uses
• Uses with inheritance
• Calls best fit
• Inspired by how a developer might manually search
• Each heuristic generates a set of examples
• Results from each are combined
• Top ten examples are returned

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Heuristics Example
Structural Context
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Calls Heuristic

• Locate examples that make similar method calls

Matched Example
Structural Context
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Calls With Inheritance Heuristic

• Locate examples that make similar method calls
  and have similar parents

Matched Example
Structural Context
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Calls Best Fit Heuristic
Locate examples that dont make too many
extraneous method calls
Potential Example
Structural Context
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Evaluation

• We claim that our approach requires less effort
  for developers to use
• Example Repository
• Automatically populated
• Forming queries
• Automatically created from context of editor
• Query performance
• Queries take from 3 to 10 seconds
• Question addressed
• Can developers recognize and use examples?

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Case Study

• Evaluating the effectiveness of delivered
  examples
• Two subjects, both new to the Eclipse framework
• Each given the same four development tasks
• All tasks encountered during Strathcona
  development
• Each were provided with code fragment identified
  from the documentation
• Subjects were asked to use Strathcona to help
  them complete the tasks within 3 hours

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Case Study

• Subject one completed all 4 tasks
• Subject two completed 3 of the 4 tasks
• Solutions were of high quality
• Included error cases they hadnt originally
  considered
• Subjects recognized examples that were not useful
• Subjects created new query fragments unexpected
  by us

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Discussion

• Can developers create appropriate context to
  query on?
• Informal evaluation shows that they can create
  fragments to form queries with
• Are these really examples?
• Hand-crafted examples help developers understand
  how and why to use an API
• Our examples provide help in the usage of an API

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Conclusion

• Structural context can provide relevant examples
  with less effort than previous approaches
• Example repositories can be easily populated
• Automatically form query based on the code a
  developer is writing
• Developers can use examples to complete tasks

http//cs.ucalgary.ca/rtholmes/strathcona