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Software Modules in Software Design

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'A module is a lexically contiguous sequence of program statements, bounded by ... [ Yourdon, Constantine 79] Avantages. Decomposition into easily dealt with pieces ... – PowerPoint PPT presentation

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Title: Software Modules in Software Design


1
Software Modules in Software Design
2
What is a Module?
  • A set of one or more contiguous program
    statements having a name by which other parts of
    the system can invoke it, and preferably having
    its own distinct set of variable names.
    Stevens, Myers74

3
  • A module is a lexically contiguous sequence of
    program statements, bounded by boundary elements,
    having an aggregate identifier. Yourdon,
    Constantine 79

4
Avantages
  • Decomposition into easily dealt with pieces
  • can abstract call by descriptive naming
  • break up program into system architecture
  • reduce complexity that one inspector needs to
    view when considering a design concept
  • debug by following trail of destruction through
    interfaces to independent module for repair
  • what properties does a module need to accomplish
    all this?

5
Conservation of Complexity
  • Move complexity of singular program module to
    interfaces between less complex modules
  • hierarchy and decomposition, divide and conquer
  • Net complexity is conserved, but it is divided so
    as to give programmers some leverage?

6
Cohesion and Coupling(a system concept!)
  • Cohesion
  • the degree of interaction within a module
  • Coupling
  • the degree of interaction between modules

7
Module Cohesion
  1. Informational
  2. Functional
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