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and the
Antikythera Mechanism
@mheap at #phpbnl17
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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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http://abstrusegoose.com/432
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40-80% of a project
is maintenance
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Maintenance
is good!
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Our job is to read
code, Not to write it
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No content
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No content
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Where do
we start?
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README.md
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No content
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No content
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No content
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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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What is dangerous?
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What should be saved?
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Who created this?
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Reconnaissance Time
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No content
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I'm sorry, Dave. I'm
afraid I can't do that
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$ grep -lr "sorry, Dave" *
src/HAL/Security/DoorPasswordValidator.php
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namespace HAL\Security;
use HAL\Security\Validator;
class DoorPasswordValidator extends Validator {
private $doorPassword = 'beneluxisawesome';
public function validate($input) {
if ($this->doorPassword !== $input) {
throw new \Exception("I'm sorry, Dave. I'm afraid
I can't do that");
}
return true;
}
}
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We’re in!
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Navigation
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Read the code
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No content
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Don’t trust the
comments
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namespace Casino\Game;
class Roulette {
/**
* Returns a random number
*/
private function alwaysReturnSix(){
}
}
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namespace Casino\Game;
class Roulette {
/**
* Returns a random number
*/
private function alwaysReturnSix(){
return 4;
}
}
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Don’t trust
the code
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Look for
side effects
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public function triggerFireAlarm() {
$this->startSprinklers();
$this->callFireBrigade();
$this->releaseDoorLocks();
}
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Double Check
Your Understanding
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Names are
important
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Find Patterns
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Prove you
understand it
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I don’t
understand it
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Debugging
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use everything
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Everything goes
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DDD
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Die Driven Debugging
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Does this code
even run?
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/**
* Returns a random number
*/
private function alwaysReturnSix() {
die('Yes it does');
return 4;
}
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echo '######################'.PHP_EOL;
echo count($vistorsInLastDay);
echo '######################'.PHP_EOL;
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if (count($visitorsInLastDay) > 5){
var_dump(visitorsInLastDay);die;
}
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echo '######################'.PHP_EOL;
var_dump(debug_backtrace());
echo '######################'.PHP_EOL;
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class MyVerifier extends SomethingVerifier {
public function userIsAdmin($user) {
return true;
}
}
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XDebug
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XDebug.scream
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XDebug_break();
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if (count($visitorsInLastDay) > 5){
xdebug_break();
}
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XHPROF
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DDD +XDebug
+ XHProf == WINNING
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Observer Effect
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I’m feeling better
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But I’m still noT 100%
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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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What changes
together?
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Explicit
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commit 0dc164fb052f4b838a674648aa29d83b60f01fa2
Author: Rasmus Lerdorf
Date: Fri May 20 12:14:55 2016 +0000
Added HAL to the villa’s security system on both the front and back doors
5 2 src/Villa/Structure/Door.php
14 0 test/Villa/Structure/DoorTest.php
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Implicit
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commit 2915dabebc8b87b84ec40fac0f4954fb84f3b7cd
Author: Rasmus Lerdorf
Date: Sun May 22 21:27:31 2016 +0000
Bought a new car. Updated town parking permit to new registration
12 0 src/Garage/Car/Ferrari.php
1 1 src/Town/ParkingPermits/Rasmus.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/Library.php,26,181
src/Casino/Game/Roulette.php,22,76
src/Controller/HallwayController.php,21,110
src/People/Cleaner.php,19,91
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entity,age-months
src/Security/PasswordManager.php,1
src/People/Cleaner.php,1
src/Casino/Game/Roulette.php,3
src/Security/SafeCombination.php,7
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entity,coupled,degree,average-revs
src/People/Cleaner.php,src/HAL/Security/DoorPasswordValidator.php,100,19
src/Room/Lounge/Wallpaper.php,src/Room/Bedroom/Wallpaper.php,60,10
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entity,coupled,degree,average-revs
application/config/config.php,application/config/database.php,90,6
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Visualisations Help
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symfony/symfony
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rails/rails
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symfony/symfony
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rails/rails
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Code Ownership
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Author Coupling
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Code Ownership
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Code Ownership
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Commit Msg
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Commit Msg
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Commit times
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Commit History
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github/adamtornhill/code-maat
Codescene.io
codehistoryminer.com
github/smontanari/code-forensics
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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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Attribution
https://upload.wikimedia.org/wikipedia/commons/f/f5/
Second_world_war_europe_1943-1945_map_en.png CC-BY-SA
https://archive.org/details/PET717_Var3 CC-BY
https://www.flickr.com/photos/132130100@N02/27448816326/ CC-BY-ND
https://www.flickr.com/photos/rockandrollfreak/10154906473 CC-BY-ND
https://www.flickr.com/photos/johnwardell/80125882 BY-NC-ND
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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!
https://joind.in/talk/b0184