Cs427-17 - Refinement Alan Perlis Epigrams on Programming 15 Everything should be built topdown except the first time CS427 17-1 Abstract Data Type

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CS427 17-1 Refinement Alan Perlis: Epigrams on Programming 15. Everything should be built top-down,  except the first time. 
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CS427 17-2 Abstract Data Type Formalism based on solid mathematics Define a type as  a set a set of operations on that set a set of properties that the operations must  have
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CS427 17-3 Complex Numbers Complex:  Real X Real =: Complex X Complex -> Boolean +: Complex X Complex -> Complex -: Complex X Complex -> Complex *: Complex X Complex -> Complex real: Complex -> Real imag: Complex -> Real
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CS427 17-4 2200  c,d: Complex real(c+d) = real(c)+real(d) imag(c+d) = imag(c)+imag(d) real(c*d) = real(c)*real(d)-imag(c)*imag(d) imag(c*d) = real(c)*imag(d)+  imag(c)*real(d) (real(c)=real(d)   imag(c)=imag(d))   c=d
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CS427 17-5 Abstract Data Types Based on math - no side effects Easy to prove things about an ADT Programming languages (Modula, Ada)  had variables and side effects Object-oriented programming based on  objects with identity and with changeable  state
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CS427 17-6 ADT vs. Objects Value Object object that is really an ADT instance variables set ONLY by constructor
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This note was uploaded on 06/14/2009 for the course CS 427 taught by Professor Jones during the Fall '07 term at University of Illinois at Urbana–Champaign.

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Cs427-17 - Refinement Alan Perlis Epigrams on Programming 15 Everything should be built topdown except the first time CS427 17-1 Abstract Data Type

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