Software design technique.

1. Welcome to Fail Fast
Session By @AlSayedGamal
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2. Fail Fast
By @AlSayedGamal
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3. Agenda
Fail Immediately!
Assertion!
Eliminate the debugger!
Fail fast and robust software.
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4. Q1:What’s the most annoying
part of software development ?
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5. A: Debugging
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6. Q2:What are the most
hated bugs ?
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7. A: Bugs that appear unexpectedly
after a long time of operating
normally!
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8. Fail Fast is the solution
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9. Fail Immediately
Fail Fast concept can be digested as failing
immediately and clearly.
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10. Can you debug this ?
Imagine this in a web based app & the developer had a typo in config file
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11. What about debugging this ?
Same typo will be spotted immediately.
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12. Fail Fast Fundamentals
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13. Assertions
What’s assertion ?!
Make sure that your language fails on assertion error.!
When is the most suitable time to do assertion.!
Assertion doesn’t conflict with logging.
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14. Design your assertions
Only if your language doesn’t have a powerful one already
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15. * ‫هوين؟‬ ‫بط‬
*But when ?
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16. –Jim Shore
“However, it’s tough to know when to add assertions.
One way to tell is to look for comments.”
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17. The Killing Exception
When Assert.notNull() can save your life.
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19. Debug this.
The hair pulling phase.
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20. but when ?*
‫؟‬ ‫هوين‬ ‫*بط‬
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21. Assertion not required
Assertion required
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Rule of thumb

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Eliminate the debugger

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and even better
If the maxConnections wasn’t found or mistyped it will throw!
something like this one:

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Fail fast robust software
Global exception handler

25. Summary
Don’t fail silently and save your time and out time.!
Assert whenever you comment.!
Assert.notNull(_instanceVariable).!
Fail with description.!
Use a global handler for users sake.
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26. References
http://www.martinfowler.com/ieeeSoftware/failFast.pdf!
en.wikipedia.org/wiki/Fail-fast
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27. Questions ?
@AlSayedGamal

28. Thank you!