Programming practises and project management for professionnal software development

Introduction
Best Programming Practices
Software Quality
Project Management
Summary
Programming Practices and Project Management
for Professional Software Development
Sébastien Jodogne
CHU of Liège
Interfaces-Entreprises ULg, May 28th, 2013
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1 Introduction
2 Best Programming Practices
Put Your Code in Revision Control Software
Coding Style and Documentation
Don’t Reinvent the (Squared) Wheel
Design Patterns
Other Recommendations
3 Software Quality
Software Engineers are Part of the Testing
Assertion-Driven Testing
Unit Testing
Integration and System Testing
4 Project Management
Agile Methodologies
Scrum
Extreme Programming
5 Summary
Score Your Project!

Introduction
Software Quality
Project Management
Summary
Who Am I?
PhD in Computer Science, ULg. Domains of interest:
Image Processing,
Machine Learning,
High-Performance Computing,
Theoretical Computer Science.
5-year professional experience in private companies:
CCTV – Closed Circuit Television (Secosys, Euresys),
Machine Vision (Euresys),
Broadcasting (EVS).
Now: Medical imaging engineer in the Department of Medical
Physics at the CHU of Liège.
This talk: Industrial practices for compiled languages.
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Introduction
Software Quality
Project Management
Summary
Case Study
Summary
Lightweight, scriptable server for medical imaging.
Open-source (GPLv3).
Developed with an industrial methodology.
Main languages:
Core: C++.
GUI: HTML5, JavaScript.
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Introduction
Software Quality
Project Management
Summary
Design Patterns
Advantages
Keep track of all the changes to the code.
Share across multiple computers, with multiple collaborators.
Track the various versions of the software (“tagging”).
Backup (recover deleted or modiﬁed ﬁles).
Avoid the ZIP mess (which version is the latest one?).
Candidates
1 Mercurial.
2 Git (more adapted to geeks).
3 Subversion (becomes legacy).
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Introduction
Software Quality
Project Management
Summary
Design Patterns
Questions When Starting a Project
Choose a licensing model (cf. Jérémie Fays). GPLv3 is the
de-facto choice.
Choose a software forge:
For closed-source (private): BitBucket, SourceForge.
For open-source (public): GitHub, Google Code.
For conﬁdential code (medical data, spin-oﬀ): ???
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Introduction
Software Quality
Project Management
Summary
Design Patterns
Choose (and Stick to) a Coding Style
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Introduction
Software Quality
Project Management
Summary
Design Patterns
Documentation
Document functions and classes in the source code
⇒ Doxygen (C/C++), Javadoc (Java), XML (C#).
Document architecture and algorithms elsewhere (separate
ﬁles or Wiki).
Don’t forget the User Manual (PDF or Wiki).
Be verbose and use explicit names (possibly long) for variables,
functions and methods.
⇒ “Self-Documented Code”.
Do not reuse variables and introduce them only when they are
needed (not at the top of a function as in C).
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Introduction
Software Quality
Project Management
Summary
Design Patterns
Use third-party libraries.
⇒ Know your ecosystem (language, frameworks, StackOverﬂow).
Recommended libraries for C++: STL, Boost, SQLite, Qt. . .
Caveats:
Minimize the number of dependencies!
Avoid heavyweight, not supported or “exotic” libraries.
Pay attention to portability (Windows, Mac OS).
License compatibility.
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Introduction
Software Quality
Project Management
Summary
Design Patterns
Anti-Patterns (Don’ts!)
Programs whose structure is
barely comprehensible, espe-
cially because of misuse of code
structures (especially GOTO).
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Introduction
Software Quality
Project Management
Summary
Design Patterns
Classes not properly encapsulated,
thus permitting unrestricted access to
their internals.
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Introduction
Software Quality
Project Management
Summary
Design Patterns
An object that knows too much
or does too much.
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Introduction
Software Quality
Project Management
Summary
Design Patterns
Conclusions
Learn and recognize bad software architectures.
Inventories do exist!
Lasagna code,
Magic numbers,
Poltergeists,
Error hiding. . .
[Antipatterns, Code smells, Fifth-System Eﬀect]
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Introduction
Software Quality
Project Management
Summary
Design Patterns
Design Patterns (Do’s!)
Recurring solutions to common
problems in software design.
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Introduction
Software Quality
Project Management
Summary
Design Patterns
Design Patterns (Do’s!)
Basic Philosophy
Uncouple the software components by adding abstractions (“Java
interfaces”), thanks to object-oriented programming.
[Wikipedia, Head First Design Patterns]
Some Common Patterns
Singleton.
Factory.
Observer.
Model-View-Controller (aka. separate GUI and core).
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Introduction
Software Quality
Project Management
Summary
Design Patterns
RAII — Resource Acquisition Is Initialization
Most useful design pattern for C++.
Automatic release of a resource on leaving scope or on
exception ⇒ Never any leak!
Applicable to memory allocation, I/O, multithreading. . .
class FileWriter
{
private:
FILE* fp_;
public:
FileWriter(const char* filename)
{
fp_ = fopen(filename, "w");
}
~FileWriter()
{
printf("Closing filen");
fclose(fp_);
}
};
void Demo1()
{
FileWriter w1("/tmp/hello.txt");
// Leaving scope => closing "w1.fp_"
}
void Demo2()
{
FileWriter w2("/tmp/hello.txt");
throw std::runtime_error("Sorry guy");
// Exception => closing "w2.fp_"
}
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Introduction
Software Quality
Project Management
Summary
Design Patterns
1 KISS (“Keep it simple, stupid”) — A code is written once, but
read many times by diﬀerent people!
2 DRY (“Don’t repeat yourself”) — Implement some
computation at a single place to ensure consistency.
3 “Premature optimization is the root of all evil” [D. Knuth].
4 Use exceptions, never return error codes (except in C).
5 Use a build system (CMake, SCons or Visual Studio).
6 Windows-only: Do not create DLL and favor static linking,
except if you know what you are doing (ABI, DLL hell)!
7 Learn debugging tools:
Debuggers (Visual Studio, Eclipse, gdb. . . ).
Linux-only: Valgrind (memory leaks, access violations. . . ).
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Introduction
Software Quality
Project Management
Summary
Unit Testing
What is Legacy Code?
Legacy code is deﬁned as
code without tests.
⇓
Impossible to know when
things get broken (i.e. to
detect regressions).
⇓
Impossible to refactor.
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Introduction
Software Quality
Project Management
Summary
Unit Testing
“Testing is up to the Testers and the Users!”
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Introduction
Software Quality
Project Management
Summary
Unit Testing
“Testing is up to the Testers and the Users!”
Really? Bugs detected at the
code level are:
Easier to understand,
Easier to reproduce,
Easier and cheaper to ﬁx,
More contained.
⇓
Software engineers are part of
the testing process!
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Introduction
Software Quality
Project Management
Summary
Unit Testing
Assertion-Driven Testing (aka. Invariants/Preconditions)
#include <assert.h>
#include <stdio.h>
int factorial(int value)
{
assert(value >= 0);
if (value == 0)
return 1;
else
return value * factorial(value - 1);
}
int main()
{
printf("%dn", factorial(-5)); /* => crash */
}
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Introduction
Software Quality
Project Management
Summary
Unit Testing
Unit Testing
int main()
{
printf("%dn", factorial(0)); /* 1 */
}
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Introduction
Software Quality
Project Management
Summary
Unit Testing
Unit Testing
int main()
{
}
⇒
TEST(Example, Factorial)
{
ASSERT_EQ(1, factorial(0));
}
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Introduction
Software Quality
Project Management
Summary
Unit Testing
Unit Testing
int main()
{
}
⇒
TEST(Example, Factorial)
{
}
Basic Idea
Accumulate a database of tests!
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Introduction
Software Quality
Project Management
Summary
Unit Testing
Unit Testing In Practice
Use a unit testing framework (e.g. Google Test).
Move your main() tests as unit tests.
Keep your unit tests small and fast.
Add unit tests each time a function or a class is added.
Add an unit test for each solved bug.
Execute the unit tests as a step of the build process!
Even better: Write tests before writing the code (aka. TDD
— Test-Driven Development).
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Introduction
Software Quality
Project Management
Summary
Unit Testing
Continuous Integration Server (Build + Unit tests)
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Introduction
Software Quality
Project Management
Summary
Unit Testing
Diﬀerent Flavors of Quality Assurance
Classes
Functions
Executable
Hardware/OS
Unit testing
Integration testing
System testing
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Introduction
Software Quality
Project Management
Summary
Unit Testing
Integration Tests
“End-to-end” tests on the ﬁnal binaries (black box).
Typically less automated and much more lengthy than unit
tests (white box).
Possible approaches:
1 Inject stimuli, compare outputs with expected results.
2 GUI automation testing.
3 Challenge the API (cf. Orthanc).
Run integration tests (at least) before each release, or even
better as part of the nightly builds.
System Tests
At last, the testing team makes user-level tests.
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Introduction
Software Quality
Project Management
Summary
Unit Testing
Issue Tracker: Link between Engineers, Testers and Users
Common Choices
Bugzilla, JIRA, FogBugz, Redmine, Trac.
Often integrated within the software forge.
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Introduction
Software Quality
Project Management
Summary
Unit Testing
The Software Quality Iceberg
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Introduction
Software Quality
Project Management
Summary
Agile Methodologies
Scrum
Extreme Programming
A New Vision of Project Management
The cathedral (monolithic)
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Introduction
Software Quality
Project Management
Summary
Agile Methodologies
Scrum
Extreme Programming
A New Vision of Project Management
⇒
The cathedral (monolithic) The bazaar (agile)
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Introduction
Software Quality
Project Management
Summary
Agile Methodologies
Scrum
Extreme Programming
Agility: Cut Down Release Cycles
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Introduction
Software Quality
Project Management
Summary
Agile Methodologies
Scrum
Extreme Programming
Agility: Cut Down Release Cycles
⇒
Features are incrementally added.
Software architecture is continuously refactored.
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Introduction
Software Quality
Project Management
Summary
Agile Methodologies
Scrum
Extreme Programming
Continuous Testing is at the Center of Agile Development
⇒
The cathedral (monolithic) The bazaar (agile) 29 / 34

Introduction
Software Quality
Project Management
Summary
Agile Methodologies
Scrum
Extreme Programming
Scrum: Most Popular Agile Methodology
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Introduction
Software Quality
Project Management
Summary
Agile Methodologies
Scrum
Extreme Programming
Scrum: The Product Backlog of Orthanc in Trello
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Introduction
Software Quality
Project Management
Summary
Agile Methodologies
Scrum
Extreme Programming
Extreme Programming: Agile Engineering Practices
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Introduction
Software Quality
Project Management
Summary
Score Your Project!
Score Your Project!
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Introduction
Software Quality
Project Management
Summary
Score Your Project!
Any Question?
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Programming practises and project management for professionnal software development

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