THE STATEFUL ELEPHPANT

RICK KUIPERS / @RSKUIPERS

@PHPSTORMTIPS

STATE

CODE EXAMPLE

THE STATE PATTERN

CODE EXAMPLE

THE STATE STRATEGY PATTERN?

STRATEGY PATTERN

! Tries to achieve similar result for input

! Strategies can’t transition to otherstrategies

! Strategy processes the input and givesoutput back to the wrapper

STATE PATTERN

! Result can be completely different

! States can trigger transitions to otherstates

! State controls the behaviour of itscontext object (ElePHPant)

WHY SHOULD WE CARE?

CHECKOUT

PAYMENTDETAILS REVIEW

CODE EXAMPLE

PROS

! Independent blocks of logic

! Easy to add new states without touching existing code

! Can easily be coordinated

THE STATE MACHINE

THE STATE MACHINE

Ileft Iright Idown Iup Ispace

Sidling Srunning Srunning Scrouching Sjumping Ashoot

Srunning - - Scrouching Sjumping Ashoot

Sjumping - - - - -

Scrouching - - - - -

THE STATE MACHINE

Input Current State Next State Output

le0 Sidling Srunning -

right Sidling Srunning -

up Sidling Sjumping -

space Sidling Sidling Ashoot

STATUSES

PENDINGNEW COMPLETED CANCELED REFUNDED

CODE EXAMPLE

PROS

! Our transitions are set in stone

! Centralised approach makes callbacks easy

! Good overview of all possible transitions

PACKAGES

DON’T REINVENT THE WHEEL

! https://github.com/winzou/state-machine

! https://github.com/Sylius/SyliusFlowBundle

! https://github.com/rskuipers/stateful-elephpant

! https://github.com/rskuipers/stateful-elephpant-talk

4

HTTPS://JOIND.IN/TALK/DA5ED

FEEDBACK

@RSKUIPERS

RICK KUIPERS

QUESTIONS?

RSKUIPERS@ENRISE.COM