In-class notes for 04/18/2014 (CS 121B (CS1), Spring 2014)

In-class notes for 04/18/2014

CS 121B (CS1), Spring 2014

Homework assignment
Quiz
Project planning -- next week

Remaining new topics: more on objects/classes; simulation

Submitted questions on assignments and technology

Python objects are created by calling the name of their class as a function, and providing arguments for __init__().

Example:
```
    acct = Acct(450)
```
When a constructor is called, three steps occur:
1. A new object of that type is allocated in memory.
2. The state variables of that new object are assigned values, by calling __init__() and passing the constructor args.
3. That newly allocated object is returned.
Python automatically carries out steps 1 and 3. A program affects the process by defining a method __init__() whose steps are carried out in step 2.
Corrected specs

Consider a spec for an InterestAccount class, or a TradeBook class, or a Tree class...
Inheritance: when one class automatically receives (inherits) the state variables and methods of another.

Superclass: A class that provides inherited state variables and methods

Subclass: A class that receives (obtains?) inherited state variables and methods.
Spec for IntAccount
Python implementation of inheritance:
- To specify a superclass:
```
    class Subcl(Supercl):
```
- To call the superclass's __init__() within the subclass's
- To call a superclass's method, use super(), e.g.,
```
    super().getBalance()
```
  ______
- ______
- ______
- ______
- ______
- ______
- ______
- ______
______
To call a superclass method that has the same name as a subclass method:
```
    Supercl.meth(self, args)
```

Calling superclass constructor with super()

    def __init__(self, ...):
	super(self, ...)

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