Code Reviews in Python - PyZh

Code Reviews in PythonCésar Cárdenas DesalesZürich Python User Group, June 2016

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About me

● Software Architect at Webrepublic AG

● Python user since v.2.0

● Co-organizer of the Swiss Python Summit

¿What are Code Reviews?

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Systematic examination of computer source code…- Wikipedia

Benefits

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● Timeless

● Spread knowledge

● The Ego Factor

● Increase quality of software

Timeless

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● Being here for a while (Fagan, 1976)

● Not going away any time soon

● Technology agnostic

● Not a fad

Timeless

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● Fad?○ Machine learning? ○ SOA? ○ OOP?○ Client server architecture?○ Big data?○ Cloud computing?○ SVN

● Fad ○ Aspect Oriented Programming○ Java applets○ Visual Programming○ Enterprise JavaBeans○ CGI (Web)○ Webmasters

Spread knowledge

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● Beginners learn from the experts’ code

● The experienced get to know other modules or systems

● Increases “Bus Factor”

The Ego Factor

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● No “quick and dirty” fixes

● Reputation at stake on each commit

Increase quality of software

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● Reviewed solutions tend to be better

● Defects are found and fixed early

Source: IBM Systems Sciences Institute

Assign Reviewers

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● Everyone participates

● Works well with couples

● ¿How long? ~1 sprint or week

Assign Reviewers

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● 50%

● 100%

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Code Review with Github

ImplementationPull

Request

Discusion

Preparation Revision Closure

Revision

Merge

Branch

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Commit

Preparation

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1. Branch

2. Commit

3. Pull Request

Revision

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4. First response

5. Review code

6. Written comments / discussion

Closure

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6. Implement changes under agreement

7. Merge

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Rule #1

It’s not personal

Basic Rules

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● Respond (ACK) and solve in a timely manner

● Not too little, not too much (400 loc. max.)

● Ask before overwriting somebody’s code

● Use checklists

Code conventions and style guides

Criteria - Pythonic code

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Pycodestyle / Flake8 / Pylint



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Pythonic code

pycodestyle / Flake8 / Pylint



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Pythonic code

pycodestyle / Flake8 / Pylint


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Zen of Python

>>> import thisThe Zen of Python, by Tim Peters

Beautiful is better than ugly.Explicit is better than implicit.Simple is better than complex.Complex is better than complicated.Flat is better than nested.Sparse is better than dense.Readability counts....

Pythonic code


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Pythonic code


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Pythonic code


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Pythonic code


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TODO/FIXME: Name and shame, ticket number, date

Criteria

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Cyclomatic complexity

Criteria

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Input data validation

Updated comments & docstrings

Dead or commented out code

Criteria

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exec() / eval()

Passwords or tokens in repository

Automated unit tests: unittest / pytest / nose / coverage

Criteria

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Efficient algorithms

Edge cases / off by 1 errors

Duplicated code / copy & paste

Criteria

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Antipatterns

● God class/function

● Lasagna code

● Magic numbers

● Reinventing the wheel (!)

Criteria

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Antipatterns

● Circular dependencies(relative imports)

● Premature optimization -> YAGNI

● Boat Anchor

● Object Orgy

Criteria

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Is there a better solution?

Is it scalable?

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Let’s make it happen.Thanks!

[email protected]@ccdesales

Code Reviews in Python - PyZh

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