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PROTOCOLS
ALL THE WAY DOWN
DOT SWIFT | PARIS, FRANCE | JANUARY 2018
@DESIGNATEDNERD | BAKKENBAECK.COM | JUSTHUM.COM
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PROTOCOL-ORIENTED
PROGRAMMING
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PROTOCOL-ORIENTED
PROGRAMMING
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PROTOCOLS WITH
DEFAULT IMPLEMENTATIONS
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DEFAULT PROTOCOL IMPLEMENTATION
extension
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CONDITIONAL
DEFAULT PROTOCOL IMPLEMENTATION
extension
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extension
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where Self:...
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github.com/designatednerd/
ProtocolPlayground
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MULTIPLE
where CLAUSES
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SUBCLASS-LIKE BEHAVIOR
WITHOUT
THE BAGGAGE OF SUBCLASSING
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CENTRALIZATION!
DRY CODE!
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NO INSANE
INHERITANCE TREES
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PROTOCOL-ORIENTED
! PITFALLS
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POP QUIZ
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TYPE INFERENCE: !
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TYPE INFERENCE: !
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TYPE INFERENCE: !
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SPECIFYING PROTOCOL TYPE: !
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SPECIFYING PROTOCOL TYPE: !
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SPECIFYING PROTOCOL TYPE: !
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SPECIFYING PROTOCOL TYPE: !
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SPECIFYING PROTOCOL TYPE: !
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DEFAULT IMPLEMENTATIONS
VS.
EXTENSIONS
VS.
SUBCLASSES
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DEFAULT IMPLEMENTATIONS
**(PLAIN VANILLA OR CONDITIONAL)
VS.
EXTENSIONS
VS.
SUBCLASSES
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> Do I need this to work on all instances and/or
subclasses of a particular thing?
Extension!
> Do I need this method to work only when I say it should,
or in a particular combination of circumstances?
Default implementation!
> Does this always need to be called from a particular
lifecycle or delegate method?
Subclass!
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CHOOSE YOUR TOOLS
WISELY
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! MERÇI BEAUCOUP! !
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LINKS!
> Protocol-Oriented Programming, WWDC 2015
developer.apple.com/videos/play/wwdc2015/408
> The ghost of Swift Bugs Future, Alexandros Salazar
nomothetis.svbtle.com/the-ghost-of-swift-bugs-
future
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PHOTO CREDITS!
> Businessman, by Daniel X. O'Neil
flickr.com/photos/juggernautco/6037175371
> Hammered Screw, by Justin Baeder
flickr.com/photos/justinbaeder/5317820857
> Knot, by JP Davidson
flickr.com/photos/jpdavidsonimages/4677642617