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Informatics 122Software Design IILecture 6

Emily Navarro

Duplication of course material for any commercial purpose without the explicit written permission of the professor is prohibited. 1

+Today’s Lecture

Design aesthetics

Your BeNumbered designs

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+But first… A Few Updates about Assignment 2

Deadline extended to Tuesday, February 4

Remember, no real GUI is required But you should show the intermediate boards

after each sequence is removed but before the spaces are filled in with random numbers

and after the spaces are filled in with random numbers

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+Design Aesthetics

What makes a given software implementation design “beautiful”?

What is it that makes someone appreciate a particular software implementation design?

What are the qualities that determine whether a particular software implementation design is “good” or “bad”?

What is it, then, that we can strive for in creating a software implementation design that will help others in appreciating it?

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+Purpose of Implementation Design An implementation design is a road map

An implementation design describes a path from application / interaction / architecture design to the product

An implementation design describes what the implementers should do

An implementation design is a guide towards future change

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+Purpose of Implementation Design An implementation design is a road map

understandable, unambiguous, consistent, helpful, … uses a good naming schema

An implementation design describes a path from application / interaction / architecture design to the product correct, complete, concise, verifiable, effective, …

attention to detail, well-documented, has clear flow, has a clear layout, has a clear interaction between classes, uses UML syntax correctly

An implementation design describes what the implementers should do elegant, partitionable, recomposable, resilient, …

An implementation design is a guide towards future change evolvable, …

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+Less of a Shared Understanding

An implementation design is a road map understandable, unambiguous, consistent, helpful, … uses a good naming schema

An implementation design describes a path from application / interaction / architecture design to the product correct, complete, concise, verifiable, effective, …

attention to detail, well-documented, has clear flow, has a clear layout, has a clear interaction between classes, uses UML syntax correctly

An implementation design describes what the implementers should do elegant, partitionable, recomposable, resilient, …

An implementation design is a guide towards future change evolvable, …

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+Some Caveats

We are going to be showing, praising, and critiquing your designs not to ridicule, rather to provide constructive feedback

This is a normal part of any design studio class

Rules of the game do not identify someone, even if you know whose design it is someone may choose to volunteer and explain their design, but

they may also choose not to do so

We only highlight parts of certain designs, so please do not correlate our comments here with your final grade for this assignment

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+Designs Rated Highly By Peers

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25

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+Some “Obvious” Room for Improvement

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+Important Points to Observe (Assignment) Being a “1” or a “5” on someone’s ranking is not an

absolute evaluation if you are a “1” on someone’s ranking, the other designs may

have all been relatively poor if you are a “5” on someone’s ranking, the other designs may

have all been relatively stellar

Length of the document may be an indicator in peer’s rankings, but not necessarily in ours

It is easier to review than to design, or is it?

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+Important Points to Observe (UML)

Having a document “heavy on UML” by itself is not a guarantee for a great design it may indeed be more complete it may also be less understandable

If we cannot find the “flow” in the UML diagram, something tends to be wrong for some designs, we end up searching for their meaning for others, it is clear from the diagram

physical layout, often, has something to do with this

Design languages are a factor UML by itself is insufficient

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+Important Points to Observe (Process) Where to start?

what about with the set of nouns in the description of the problem (e.g., grid, cell, sequence, flame number, …)

what about with the set of verbs in the description of the problem (e.g., chooses adjacent cells, cells are swapped, cells are emptied …)

Work towards completeness does my current design account for all possible features does it do so explicitly, or are some features hidden

This is merely a rough and rules of thumb process, but one that tends to help the beginning designer

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+A Checklist for the Overall Process

Apply rigor

Separate concerns modularize abstract

Anticipate change

Generalize

Work incrementally

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+A Checklist for Overall Design

Strive for grouping related functionality (high cohesion)

Strive for ungrouping semi-related functionality (high cohesion)

Strive for reducing interdependency (low coupling)

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+A Checklist on Class Design

Cohesion

Completeness

Convenience

Clarity

Consistency

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+A Checklist on Principles and Strategies Principles

keep it simple, stupid! (KISS) information hiding acyclic dependencies …

Strategies program to the interface refactor apply software patterns …

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