How Programmers See The World

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How Programmers See The World

• OBSESSIVELY, COMPULSIVELY ORDERED
• EVERYTHING IN ITS PLACE
• EVERYTHING HAS A PLACE
• SPELLING, UPPER and lower Case
• THERES NOTHING FREE FORM ABOUT IT
• UNFORTUNATELY, ITS A WHOLE NEW LANGUAGE

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The sky is blue

• No,
• Universe.Galaxies.MilkyWay.OurSun.Planets.
• Earth.Sky Color.blue

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Computers

• Computers.big
• Computers.small.mp3players.dontWork.iPod

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What Is This?

• Its called classification
• Youve heard this before
• A class of problems
• In a class by itself
• Classy new styles
• A Class is a container of properties and behaviors

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Talking to your computer

• Your computer speaks through the keyboard and
  monitor
• Not like anything youve
• ever seen
• System.out.println
• JOptionPane.showUserDialog

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x?

• "real" numbers are rarely used in computing.
• Computer programs use "variables" that hold real
  numbers.
• x might be equal to 14 now, but something else
  later.

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Finally

• Class is the category.subCategory.subSub
• Object is an example of something of that class
• Animals.Dogs.BullDog is a class
• but
  Lemmy here is
• an
  actual dog.
• 
  Lemmy is an Object

Animals.Dogs.BullDog.Lemmy
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Note the abstraction

• Impress your friends, because this IS rocket
  science
• Abstract ? ? ? ? Specific
• General ? ? ? Concrete
• High Order ? ? ? ? Low Order
• FreeForm ? ? ? ? Details
• Class ? SubClass ? SubClass ? Object

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Solve A Problem

• What could we possibly build a computer system to
  do, that is currently being done by animals?

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Now, Objects are never alone

I see three kinds of relationships here
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Our World The Problem Space

• Real problems, in the real world. In REAL TIME.
• Real Time is an interesting concept.

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The Only Tool We Have

• The Computer The Solution Space
• Computers solve real world problems
• To be solved, the real world problem must be
  reflected in the computer
• Modeling

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Robots

• They LOOK like humans. Why?

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The Essence of Programming

• We build high quality systems to the extent that
  we can model the problem space within the
  solution space.
• Programs are models of something in the real
  world.

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Classification and Modeling

• Ponder events in the real world. Analysis
• Identify the actors (objects). Specification
• Generalize them into classes of that describe
  their, um, properties and behaviors. Model
• Why Model ? Because its not real. Its in our
  computer.

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Where do we implement our model?

• In a document. In a file. In the computer.
• Its called a computer program, but it reflects a
  MODEL, not a list of instructions.
• When the computer runs our program, it
  construct a model in memory.
• It uses classes to build objects in memory.
• The objects interact, just like the system it
  represents.

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What does the model give us?

• So what, weve recreated a little piece of the
  real world in our computer?
• It gives us INFORMATION, via SIMULATION.

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Any computer that does something

• Is a model of something in the real world
• mp3 players are bands
• Cell phones are your friends
• ATMs are bank tellers
• Robots are people
• Video games are adventures
• Nemo is an actor