| Current Forum: 15-211 Main Forum |
| Date: Mon Sep 24 2001 1:21 pm |
| Author: Shi, Ying <shy@cmu.edu> |
| Subject: the implementation of Append() in (abstract)Class List |
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according to the lectures on List, the Append() method for class List is implemented in the following way illustrated by a psydo-code example:
List a: "a"->"b"->Empty
List b: "d"->"e"->Empty
after List c = a.Append(b);
we'll have such a graph:
"
a=> "a"->"b"->Empty
b (references at "d")
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c=> "a"->"b"->"d"->"e"->Empty
"
my question is:
why implement the Append() in such way?
or why not make a copy of b as well if the purpose is to keep the original lists as later on b and c could accidentally alter each other's integrity(they share a common section)?
I would assume it's not just a lazy programming that left the other half uncopied.
by all means, I don't understand the benifits/advantages or maybe some tradeoffs that I can't picture out behind this implementation.
Thanks |
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