–Zachary Scott
“Too much magic… Um, you mean in general?
It can make make stuff simpler to understand, if
that’s your goal. But it’s easy to go too far.”
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Basis of Science
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Picking the right
abstraction is crucial
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In Computer Science,
everything is an
abstraction
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With a lot of room for
interpretation
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This makes it similar to
art
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Abstracting away
Semantics
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Generic Algorithms
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Data Abstraction
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“Dataless
Programming”
RM Balzer - 1967
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Control Abstraction
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Subroutines
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“Go To Statement
considered harmfull”
Edsger Dijkstra, 1968
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“Protection in
Programming
Languages"
James H. Morris Jr., 1973
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You should be able to
reason about modules in
isolation
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“Global Variables
Considered Harmful”
W.A. Wulf, M. Shaw, 1973
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Data Abstraction +
Control Abstraction =
Object Oriented Programming?
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#alankayholdingthings
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–Alan Kay
“OOP to me means only messaging, local
retention and protection and hiding of state-
process, and extreme late-binding of all things.”
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We make the rules
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Some rules enable
good programs
(For some definition of good.)
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Single Responsibility
Principle
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Liskov Substitution
Principle
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Law of Demeter
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Don’t abstract too
much, too early
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Is inheritance a good
abstraction?
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Used for type hierarchy
and implementation
sharing
Almost all attacks rely on
switching up or down
abstraction levels
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Social Engineering
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Abstraction
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UI as Abstraction
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Metaphor
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Colour
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Light
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Trichromacy
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?
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?
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Is magenta real?
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#
FF00FF
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Leaky abstraction?
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Space
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Tetrachromacy
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2-3% of all women?
50% of all women?
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Gene on X
chromosome
OPN1MW and OPN1MW2
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Women could have up
to six colour cones
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Mostly dysfunctional
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At least two confirmed
cases
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Seeing millions of
more colours
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Why dysfunctional?
(my own unscientific theory)
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We don’t see colours
with our eyes
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We see colours with
our brain
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Our brain adjusts
colours
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We don’t see colours we
don’t have an abstract
concept for
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When we learn to speak, colour
perception switches from left
brain side to right brain side
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Himba Tribe (Namibia)
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zuzu: dark shades of blue, red, green
and purple
!
vapa: white, some shades of yellow
!
buru: some shades of green and blue
!
dambu: some shades of green, red
and brown
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Abstraction happens
in our minds
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All abstraction
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OOP happens in our
mind, not our computer
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UI happens in our
mind, not our computer
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“Anything that is in the world when you’re born
is normal and ordinary and is just a natural part
of the way the world works.
!
Anything that's invented between when you’re
fifteen and thirty-five is new and exciting and
revolutionary and you can probably get a
career in it.
!
Anything invented after you're thirty-five is
against the natural order of things”
–Douglas Adams
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Countries exist in our
mind
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In our collective mind
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Changing abstractions is
a basic principle of
innovation and progress