CSC207.01 2014F, Class 30: OOD in Practice: Designing a List Interface
New lab partners!
- Upcoming Work.
- Extra Credit.
- The design of ADTs, revisited.
- Exercise: Designing a list ADT.
- Quick notes on implementation.
- I hope you had an awesome break! I particularly hope you had a chance
to rest and relax.
- Exam 1 to be returned at the end of class (about 11:40).
- I think I spent more time grading your exam than any of you spent
- Dr. Davis will be visiting our class tomorrow.
- Office hours
- Extended office hours this week. See outside my office.
- A correction on my interpretation of College policies on academic
honesty: In discussing the situation in CSC 151, I may have told you
that if you don't turn in work, then you cannot be charged for academic
dishonesty on that work. While the chair of the CAS subcommittee on
academic dishonesty agreed with me that it was appropriate to tell
you that for my take-home exams, the dean who serves on that committee
told me that that policy does not always apply. So don't count on it.
(I don't expect that you will ever need to count on that rule, but I
don't want to mislead you if you find that you want to.)
- Reading for tomorrow:
- Also reflect on how you might implement lists with arrays.
- CS Extras Thursday: Randomness
- Wednesday at 7:30 p.m. Internship panel with Lea and Mira and some random
Grinnellian who interned at Google.
- China's talk on A Model for Transport in Stereocilia, Tuesday at 4:15
pm in Science 2517.
- Men's Soccer, Wednesday at 4pm vs. Cornell.
- Basketball Scrimmage Wednesday at 7pm in Darby.
- Ajuna's Radio show Mondays at 8pm. Listen to African music
- Ajuna MC's talk on Sustainability of Grinnell Wednesday at noon in ARH 102.
- Ezra's Radio show Thursdays at midnight. Radio melodrama.
- Charlie's Friday Night "War in Animated Film" ExCo.
- Saturday fall festival to support MICA. 4-8 pm in Main Quad.
- Cook for ISO Food Bazaar. (You need to submit recipes in order to do this.)
- Eat at ISO Food Bazaar.
The design of ADTs, revisited
What are the key ideas in designing an ADT?
- Philosophy - The primary idea that drives the ADT; what distinguishes
it from others
- Use cases - Ways in which we use the data type
- Methods - The functions that it supports
Exercise: Designing a list ADT
With your partner, answer each of the following. (I'll probably stop
you along the way to share and compare answers.)
What is the basic "philosophy" of lists?
- Lists are homogensous collections of values that grow dynamically.
- Or are lists heterogenous collections of values that grow dynamically.
- You should be able to access an element at a specific index.
- Or is that more of an array/vector?
- In which you can insert elements at various positions
- And you can rearrange the elements VETO
- The elements are "in order" (as compared to a "set" or "bag")
- There's a first (in the nonempty list)
- There's a last (in the nonempty list)
- Each element except the last has a next element
- Each element except the first has a previous element
- The client of the list determines the order
Can we efficiently insert and index? (Efficiently usually means O(1),
at least in this case.)
- We can't think of a way.
- So we can give up indexing.
Sam's attempt to tie our ideas together.
- Lists are dynamic, homogenous, client-ordered, linear collections of values.
- By dynamic, we mean that you can add or remove elements.
- By client-ordered, we mean that ...
What's the difference between how we think about a Vector (dynamic array)
and a List?
- In vectors, we don't assume indices of values change
- In lists, we expect that the implicit indices of values change when we
insert or delete.
What use cases do you envision?
What general categories of operations/methods you expect a list to provide?
- Add elements to the list (aka "insert")
- Delete elements from the list (aka "remove")
- Other mutators
- Swap elements in the list
- Set elements
- Get elements from the list
- Get the element at a particular index (?)
- Get the number of elements in the list (length)
- Determine information about the relationship between elements
- Does an element have a next element?
- Interesting big things to do with lists
- Reverse- build a reversed version of the list
- ForEach: Do something to each value in the list
What are the details of some of the methods within each category?
- list (maybe the primary object)
- value to insert
position - where to insert it
public interface SimpleList
public void insert(T value, Position p);
public void addToEnd(T value);
public void insertAfter(T here, T newvalue);
// What happens if the same value appears twice?
What's a position?
Quick notes on implementation
What are the key ideas in designing a data structure / implementing an ADT?