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and the
Antikythera Mechanism
@mheap at #PHPCONFPH
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Antikythera Mechanism
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It’s Been Stolen!
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Why do we want it?
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40-80% of a project
is maintenance
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Why so much?
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Our job is to read
code, Not to write it
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*flying noises*
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Where do
we start?
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What should be saved?
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What is dangerous?
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Who created this?
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README.md
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Talk to people
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Inventory the code
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Dependencies
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Build the project
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Accept you're
missing 10%
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Time to go in!
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Security!
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“Incorrect Password”
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$ grep -lr "Incorrect password" *
src/Architect/Security/DoorPasswordValidator.php
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namespace Architect\Security;
class DoorPasswordValidator {
private $doorPassword = 'manilarocks';
public function validate($input) {
if ($this->doorPassword !== $input) {
throw new \Exception("Incorrect password");
}
return true;
}
}
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We’re in!
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Navigation
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Draw a map
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No content
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Read the code
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Don’t trust the
comments
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namespace Architect\Game;
class Roulette {
/**
* Returns a random number
*/
private function spinRandom(){
}
}
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Don’t trust
the code
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namespace Architect\Game;
class Roulette {
/**
* Returns a random number
*/
private function spinRandom(){
return 4;
}
}
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Does this code
even run?
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/**
* Returns a random number
*/
private function spinRandom() {
die('Yes it does');
return 4;
}
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Look for
side effects
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public function triggerFireAlarm() {
$this->startSprinklers();
$this->callFireBrigade();
$this->releaseDoorLocks();
}
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Naming Things
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Find intentions
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Find Patterns
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Prove you
understand it
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I don’t
understand it
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Debugging
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use everything
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Everything goes
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DDD
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Die Driven Debugging
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echo '######################'.PHP_EOL;
echo $currentCasinoCapacity;
echo '######################'.PHP_EOL;
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if (!isset($visitors['michael_cheng'])){
var_dump($visitors);die;
}
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echo '######################'.PHP_EOL;
var_dump(debug_backtrace());
echo '######################'.PHP_EOL;
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class MyDoorMan extends DoorMan {
public function changeShiftAt($val) {
throw new Exception("Changing at $val");
}
}
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XDebug
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XDebug.scream
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XDebug_break();
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if (!isset($visitors['michael_cheng'])){
xdebug_break();
}
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XHPROF
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DDD +X Debug
+ XHProf == WINNING
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Observer Effect
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I’m feeling better
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Project History
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git log -S
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git log -S antikythera
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commit 5288d5804a3fc20dae4f3b2deeaa7f687595aff1
Author: Rasmus Lerdorf
Date: Tue May 24 09:33:59 2016 +0000
Add new secure storage facility. (Closes #42)
The existing storage facilities use symmetrical encryption keys which allow anyone with
the password to access them. The new storage is more secure and requires both a password and
my handprint.
There’s nothing in there yet but we’ll put the Antikythera in it as soon as it arrives
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What’s changed
recently?
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Temporal Coupling
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Explicit
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commit 0dc164fb052f4b838a674648aa29d83b60f01fa2
Author: Rasmus Lerdorf
Date: Fri May 20 12:14:55 2016 +0000
Changed from European to American roulette table. Gives the house a better edge
5 2 src/Architect/Game/Roulette.php
14 0 test/Architect/Game/RouletteTest.php
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Implicit
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commit 2915dabebc8b87b84ec40fac0f4954fb84f3b7cd
Author: Rasmus Lerdorf
Date: Sun May 22 21:27:31 2016 +0000
Removed the corner roulette table as it was crooked. Updated Fire plan to remove table
0 2 src/Architect/FloorPlan.php
0 1 src/Architect/Policy/FireEscape.php
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Common Causes
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Code Maat
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statistic,value
number-of-commits,2254
number-of-entities,3179
number-of-entities-changed,9979
number-of-authors,106
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entity,n-authors,n-revs
src/Room/VipLounge.php,26,181
src/Game/Blackjack.php,22,76
src/Controller/CloakroomController.php,21,110
src/People/FloorManager.php,19,91
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entity,age-months
src/Security/PasswordManager.php,1
src/Bar/DrinkPrices.php,1
src/Game/Poker/Stud.php,3
src/Security/RadioChannels.php,7
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entity,coupled,degree,average-revs
src/Manager/FloorManager.php,src/Factory/TableFactory.php,100,19
src/Vendor/Drinks.php,src/Vendor/Snacks.php,60,10
src/Room/VipLounge.php,src/Room/Cloakroom,14,172
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entity,coupled,degree,average-revs
application/config/config.php,application/config/database.php,90,6
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History Analysis
is flawed
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Leaving a legacy
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Secure the site
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Glossary
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Logging
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Name things well
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Build a knowledge map
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Leave useful comments
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//
// Dear maintainer:
//
// Once you are done trying to 'optimize' this routine,
// and have realized what a terrible mistake that was,
// please increment the following counter as a warning
// to the next guy:
//
// total_hours_wasted_here = 42
//
I’ve been @mheap, you’ve been awesome!